Raypak H7-503, H7-753, H7-1003, H7-1253, H7-1503 Installation And Operating Instructions Manual

CATALOG NO. 3400.53A
Effective: 8-1-06
Replaces: 6-15-06

INSTALLATION
AND OPERATING
INSTRUCTIONS

Models 503-2003
Types H & WH

FOR YOUR SAFETY

Do not store or use gasoline or other flammable vapors and liquids or other combustible materials in the vicinity of
this or any other appliance. To do so may result in an explosion or fire.

WARNING

Improper installation, adjustment, alteration, service or maintenance can cause property damage, personal injury,
exposure to hazardous materials* or loss of life. Review the information in this manual carefully. Installation and
service must be performed by a qualified installer, service agency or the gas supplier.

* This unit contains materials that have been identified as carcinogenic, or possibly carcinogenic, to humans.

WHAT TO DO IF YOU SMELL GAS

• Do not try to light any appliance.

• Do not touch any electrical switch; do not use any phone in your building.

• Immediately call your gas supplier from a neighbor’s phone. Follow the gas supplier’s instructions.

• If you cannot reach your gas supplier, call the fire department.

This manual should be maintained in legible condition and kept adjacent to the heater or in a safe place for future
reference.

P/N 241288 Rev 2

Table of Contents

WARNINGS................................................................2

SECTION A Before Installation ..............................3

Product Receipt .......................................................3

Model Identification................................................3

Ratings and Certifications........................................3

Installations at Elevation .........................................4

Component Locations..............................................4

General Information ................................................4

SECTION B Hot Water Supply General Safety.....5

Time/Temperature Relationships in Scalds.............6

SECTION C Installation...........................................7

Installation Codes....................................................7

Equipment Base.......................................................7

Clearances................................................................7

Combustion and Ventilation Air..............................9

Water Piping..........................................................11

Gas Supply.............................................................17

Electrical Power Connections................................19

Venting..................................................................21

Controls.................................................................28

SECTION D Start-up..............................................41

Pre Start-up............................................................41

Start-Up.................................................................42

SECTION E Operation...........................................47

Lighting Instructions .............................................47

To Turn Off Gas To Appliance.............................47

SECTION F Troubleshooting.................................49

UDB Fault History ................................................50

SECTION G Maintenance......................................51

Suggested Minimum Maintenance Schedule.........51

Preventive Maintenance Schedule.........................52

SECTION H Appendix...........................................53

Inside Air Contamination......................................53

Wiring Diagrams...................................................38

1

PAY ATTENTION TO THESE TERMS:

WARNINGS

DANGER:

WARNING:

CAUTION:

NOTICE:

DANGER: Make sure the gas on which the

heater will operate is the same type as that
specified on the heater rating plate.

WARNING: Should overheating occur or the
gas supply valve fail to shut, do not turn off or
disconnect the electrical supply to the heater.
Instead, shut off the gas supply at a location
external to the heater.

WARNING: Do not use this heater if any part
has been under water. Immediately call a
qualified service technician to inspect the
heater and to replace any part of the control
system and any gas control which has been
under water.

WARNING: To minimize the possibility of
improper operation, serious personal injury,
fire, or damage to the heater:

• Always keep the area around the heater

free of combustible materials, gasoline,
and other flammable liquids and vapors.

• Heater should never be covered or have

any blockage to the flow of fresh air to the
heater.

WARNING: Risk of electrical shock. More
than one disconnect switch may be requir ed to
de-energize the equipment before servicing.

Indicates the presence of immediate hazards which will cause severe personal injury,
death or substantial property damage if ignored.

Indicates the presence of hazards or unsafe practices which could cause severe personal
injury, death or substantial property damage if ignored.

Indicates the presence of hazards or unsafe practices which could cause minor personal
injury or product or property damage if ignored.

Indicates special instructions on installation, operation, or maintenance which are impor­tant but not related to personal injury hazards.

WARNING - CALIFORNIA PROPOSI­TION 65: This product contains chemicals

known to the State of California to cause can­cer, birth defects or other reproductive harm.

CAUTION: Operation of this heater in low­temperature systems requires special piping.
Harmful internal condensation will occur if
the inlet water temperature does not exceed
105°F. Warranty claims will be denied when
condensation occurs.

CAUTION: If this heater is to be installed
above radiation level, it must be provided with
a low water cut-off device at the time of heater
installation.

CAUTION: This heater requires forced water
circulation when the burner is operating. See
minimum and maximum flow rates. Severe
damage will occur if the heater is operated
without proper water flow circulation.

CAUTION: If this heater is to be installed in
a negative or positive pressure equipment
room, there are special installation require­ments. Consult factory for details.

2

SECTION C: Installation

SECTION A

Before Installation

Raypak strongly recommends that this manual be re­viewed thoroughly before installing your MVB heater.
Please review the General Safety information in Sec­tion B before installing the heater. Factory warranty
does not apply to heaters that have been improperly
installed or operated. (Refer to the warranty at the back
of this manual.) Installation and service must be per­formed by a qualified installer, service agency or gas
supplier. If, after reviewing this manual, you still have
questions which this manual does not answer, please
contact the manufacturer or your local Raypak repre­sentative.

Thank you for purchasing a Raypak product. We hope
you will be satisfied with the high quality and durabil­ity of our equipment.

Product Receipt

On receipt of your heater it is suggested that you visu­ally check for external damage to the shipping crate. If
the crate is damaged, make a note to that effect on the
Bill of Lading when signing for the shipment. Remove
the heater from the shipping packaging. Report any
damage to the carrier immediately.

When ordering parts, you must specify the model and
serial numbers of the heater. When ordering under war­ranty conditions, you must also specify the date of
installation.

Purchased parts are subject to replacement only under
the manufacturer’s warranty. Debits for defective re­placement parts will not be accepted and will be
replaced in kind only per Raypak’s standard warranties.

Model Identification

The model identification number and heater serial
number are found on the heater rating plate located on
the upper rear jacket panel of the heater. The model
number will have the form H7-2003 or similar
depending on the heater size and configuration. The
letter(s) in the first group of characters identifies the
application (H = Hydronic Heating, WH = Domestic
Hot Water (DHW)). The number which follows identi­fies the firing mode (7 = electronic modulation). The
second group of characters identifies the size of the
heater (three or four numbers representing the ap­proximate MBTUH input), and, where applicable, a
letter, indicating the manufacturing series.

On occasion, items are shipped loose. Be sure that you
receive the correct number of packages as indicated on
the Bill of Lading.

Claims for shortages and damages must be filed with
the carrier by consignee. Permission to return goods
must be received from the factory prior to shipping.
Goods returned to the factory without an authorized
Returned Goods Receipt number will not be accepted.
All returned goods are subject to a restocking charge.

Ratings and Certifications

Standards:

• ANSI Z21.13 · CSA 4.9 - latest edition, Gas-Fired

Hot Water Boilers

• CAN 3.1 - latest edition, Industrial and Commercial

Gas-Fired Package Boilers

• ANSI Z21.10.3 · CSA 4.3 - latest edition, Gas Wa-

ter Heaters

• SCAQMD Rule 1146.2

3

SECTION A: Before Installation

All Raypak heaters are National Board Approved, and
design-certified and tested by the Canadian Standards
Association (CSA) for the U.S. and Canada. Each heater
is constructed in accordance with Section IV of the
American Society of Mechanical Engineers (ASME)
Heater Pressure Vessel Code and bears the ASME stamp.
The heater also complies with the latest edition of
ASHRAE 90.1 Standard.

WARNING: Altering any Raypak pressure vessel by

installing replacement heat exchangers, tube bundle head­ers, or any ASME parts not manufactured and/or approved
by Raypak will instantly void the ASME and CSA ratings
of the vessel and any Raypak warranty on the vessel. Al­tering the ASME or CSA ratings of the vessel also
violates national, state, and local approval codes.

Installations at Elevation

Rated inputs are suitable for up to 4,500 ft elevation with­out de-rating. Consult the factory for installations at
altitudes over 4,500 ft above sea level. No hardware
changes are required to the heaters for installations up to
10,000 ft (adjustments may be required).

Top panel, blower and gas train omitted for clarity

Fig. 2: Component Locations - Top

Component Locations

Panels omitted for clarity

Fig. 1: Component Locations - Side

Fig. 3: Component Locations – Rear

General Information

Gas

Conn.

(NPT)

N P Flue Intake

Model

No.

MBTUH

Input

Water
Conn.
(NPT)

Max. Min.

503 500 125 2 1 1 6 6

753 750 188 2 1 1 6 6

1003 999 250 2-1/2 1-1/4 1 6 6

1253 1250 312 2-1/2 1-1/4 1 8 8

1503 1500 375 2-1/2 1-1/4 1 8 8

1753 1750 438 2-1/2 2 1 8 8

2003 1999 500 2-1/2 2 1 8 8

Vent Size

(in.)

Table A: Basic Data

4

SECTION C: Installation

SECTION B

Hot Water Supply

General Safety

To meet commercial hot water use needs, the high limit
safety control on this water heater is adjustable up to
210°F. However, water temperatures over 125°F can
cause instant severe burns or death from scalds. When
supplying general purpose hot water, the recommended
initial setting for the control is 125°F.

Safety and energy conservation are factors to be con­sidered when setting the water temperature on the
thermostat. The most energy-efficient operation will
result when the temperature setting is the lowest that
satisfies the needs of the application.

Water temperature over 125°F can cause instant severe
burns or death from scalds. Children, disabled and eld­erly are at highest risk of being scalded.

• Feel water before bathing or showering.

• Temperature limiting valves are available.

NOTE: When this water heater is supplying general
purpose hot water for use by individuals, a thermostati­cally controlled mixing valve for reducing point of use
water temperature is recommended to reduce the risk
of scald injury. Contact a licensed plumber or the local
plumbing authority for further information.

Maximum water temperatures occur just after the
heater’s burner has shut off. To determine the water
temperature being delivered, turn on a hot water faucet,
place a thermometer in the hot water stream and read
the thermometer.

This section applies to Hot Water Supply Boilers and
Hot Water Heaters ONLY. For sanitary rinse applica­tions where outlet temperatures of 180°F to 195°F are

required, a boiler is recommended since the 210°F limit
on water heaters will NOT allow the heater to maintain
these desired sanitary rinse temperatures.

Water temperature over 125°F can
cause instant severe burns or death
from scalds.

Children, disabled, and elderly are
at highest risk of being scalded.

See instruction manual before set­ting temperature at water heater.

Feel water before bathing or show­ering.

Temperature limiting valves are
available, see manual.

5

SECTION B: General Safety

Time/Temperature Relationships
in Scalds

The following chart details the relationship of water
temperature and time with regard to scald injury and
may be used as a guide in determining the safest water
temperature for your applications.

Water Temp. Time to Produce Serious Burn

120°F More than 5 minutes

125°F 1-1/2 to 2 minutes

130°F About 30 seconds

135°F About 10 seconds

140°F Less than 5 seconds

145°F Less than 3 seconds

150°F About 1-1/2 seconds

155°F About 1 second

Table courtesy of The Shriners Burn Institute

Table B: Time to Produce Serious Burn

CAUTION: Hotter water increases the risk of scald-

ing! There is a hot water scald potential if the
thermostat is set too high.

The temperature of the water in the heater can be regu­lated by using the Raypak Modulating Temperature
Control. To comply with safety regulations, the control
is set at 120°F when shipped from the factory (Mode 3
default setting for Tank Target).

To adjust the water temperature, follow the instruction
for the operation of the control starting on page 28 of
this manual. The control is shown below for identifica­tion purposes only. (See Fig. 4.)

Fig. 4: Modulating Temperature Control

6

SECTION C: Installation

SECTION C

Installation

Installation Codes

Installations must follow these codes:

• Local, state, provincial, and national codes, laws,

regulations and ordinances

• National Fuel Gas Code, ANSI Z223.1/NFPA 54 –

latest edition (NFGC)

• National Electrical Code, ANSI/NFPA 70 - latest

edition (NEC)

• Standard for Controls and Safety Devices for Auto-

matically Fired Boilers, ANSI/ASME CSD-1,
(CSD-1) when required

• For Canada only: CAN/CSA B149.1 Natural Gas

and Propane Installation Code and CSA C22.1
C.E.C. Part 1 (C22.1)

Equipment Base

The heater should be mounted on a level, structurally
sound surface. The heater is approved for installation
on a combustible surface but must NEVER be installed
on carpeting. Gas-fueled equipment installed in en­closed parking garages must be located at least 18 in.
above the floor.

When such locations cannot be avoided, it is recom­mended that a suitable catch pan, adequately drained,
be installed under the appliance. The pan must not re­strict air flow.

In addition, the heater shall be installed such that the
gas ignition system components are protected from
water (dripping, spraying, rain, etc.) during appliance
operation or service (circulator replacement, control
replacement, etc.).

Clearances

Indoor Installations

Heater

Side

Floor* 0” 0”

Rear 12” 24”

Right Side 1” 1”

Left Side 1” 1”

Top 0” 10”

Front Open 24”

Vent 1” 1”

* DO NOT install on carpeting.

Table C: Clearances – Indoor Installations

Minimum Clearance

from Combustible

Surfaces

Recommended

Service

Clearance

7

SECTION C: Installation

Fig. 5: Minimum Clearances from Vent/Air Inlet Terminations – Indoor and Outdoor Installations

U.S. Installations1 Canadian Installations2

Clearance above grade, veranda, porch, deck, or

A

balcony

1 ft (30 cm) 1 ft (30 cm)

4 ft (1.2m) below or to side

B Clearance to window or door that may be opened

of opening; 1 foot (30 cm)

3 ft (91 cm)

above opening

C Clearance to permanently closed window

* *

Vertical clearance to ventilated soffit located

D

above the terminal within a horizontal distance of

5 ft (1.5m)

*

2 ft (61cm) from the centerline of the terminal

E Clearance to unventilated soffit

F Clearance to outside corner

G Clearance to inside corner 6 ft (1.83m)

Clearance to each side of center line extended

H

above meter/regulator assembly

I Clearance to service regulator vent outlet

Clearance to non-mechanical air supply inlet to

J

building or the combustion air inlet to any other

4 ft (1.2m) below or to side

of opening; 1 ft (30 cm)

appliance

K Clearance to mechanical air supply inlet

Clearance above paved sidewalk or paved

L

driveway located on public property

3 ft (91 cm) above if within

10 ft (3m) horizontally

M Clearance under veranda, porch, deck or balcony

1

In accordance with the current ANSI Z223.1/NFPA 54 National Fuel Gas Code

2

In accordance with the current CAN/CGA-B149 Installation Codes

t Vent terminal shall not terminate directly above sidewalk or paved driveway located between 2 single family dwellings that serves both dwellings
TT Permitted only if veranda, porch, deck, or balcony is fully open on a minimum of two sides beneath the floor and top of terminal and underside of

veranda, porch, deck or balcony is greater than 1 ft (30cm)

* Clearances in accordance with local installation codes and the requirements of the gas supplier

* *
* *

*

3 ft (91 cm) within a height

*

15 ft above the me-

ter/regulator assembly

*

6 ft (1.83m)

3 ft (91 cm)

above opening

6 ft (1.83m)

7 ft (2.13m)

*

7 ft (2.13m) t

12 in. (30 cm) TT

Table D: Vent/Air Inlet Termination Clearances

8

SECTION C: Installation

the heater to be serviced without removing any struc­ture around the heater.

Outdoor Installations

These heaters are design-certified for outdoor installa­tion. Heaters must not be installed under an overhang
that is less than 3 ft from the top of the vent terminal.
Three sides must be open in the area under the over­hang. Roof water drainage must be diverted away from
heaters installed under overhangs.

Heater

Side

Min. Clearance

from Combustible

Surfaces

Rear 12” 24”

Right Side 1” 1”

Left Side 1” 1”

Top Unobstructed Unobstructed

Vent

12” 12”

Termination

Recommended

Service

Clearance

Venting not shown for clarity. Heater must be vented

per instructions in this manual

Fig. 6: Minimum Clearances from Combustible

Surfaces – Indoor and Outdoor Installations

When installed according to the listed minimum clear­ances from combustible construction, these heaters can
still be serviced without removing permanent structural
construction around the heater. However, for ease of
servicing, we recommend a clearance of at least 24 in.
in front, at least 24 in. on the rear and 10 in. above the
top of the heater. This will allow the heater to be ser­viced in its installed location without movement or
removal of the heater.

Service clearances less than the minimum may require
removal of the heater to service either the heat ex­changer or the burner components. In either case, the
heater must be installed in a manner that will enable

Table E: Clearances – Outdoor Installations

The combustion air intake terminal MUST be used for

outdoor installations. The hood is shipped loose and
installed on the rear of the heater at the jobsite.

Combustion and Ventilation Air

NOTICE: Use of the heater in construction areas

where fine particulate matter, such as concrete or dry­wall dust, is present may result in damage to the burner
that is not covered by the warranty. If operated in a
construction environment, a clean source of combus­tion air must be provided directly to the heater.

Indoor Units

The heater must be supplied with sufficient quantities
of non-contaminated air to support proper combustion
and equipment ventilation. Combustion air can be sup­plied via conventional means where combustion air is
drawn from the area immediately surrounding the
heater, or via direct vent, where combustion air is
drawn directly from outside. All installations must
comply with the requirements of the NFGC (U.S.) and
B149.1 (Canada), and all local codes.

9

SECTION C: Installation

CAUTION: Combustion air must not be contaminated

by corrosive chemical fumes which can damage the
heater and void the warranty. (See Section H.)

NOTICE: It is recommended that the intake vent be

insulated to minimize sweating.

Optional Construction Air Filter

An optional construction air filter is available for use.
The filter should be removed after construction is fin­ished to allow for unrestricted air flow to the heater.

Direct Vent

If outside air is drawn through the intake pipe directly
to the unit for combustion:

1. Install combustion air direct vent in accordance

with Fig. 24 (horizontal) or Fig. 25 (vertical) of
this manual (pages 26 & 27 respectively).

2. Provide adequate ventilation of the space occupied

by the heater(s) by an opening(s) for ventilation air
at the highest practical point communicating with
the outdoors. The total cross-sectional area shall be
at least 1 in.

2

mm

per kW) of total input rating of all equipment

2

of free area per 20,000 BTUH (111

in the room when the opening is communicating
directly with the outdoors or through vertical
duct(s). The total cross-sectional area shall be at
least 1 in.
mm

2

2

of free area per 10,000 BTUH (222

per kW) of total input rating of all equipment
in the room when the opening is communicating
with the outdoors through horizontal duct(s).

3. In cold climates, and to mitigate potential freeze-

up, Raypak highly recommends the installation of
a motorized sealed damper to prevent the circula­tion of cold air through the heater during non­operating hours.

TruSeal™ Combustion Air

In addition to the 3 previous steps, combustion air may
be ducted directly to the heater by using PVC, CPVC
or sealed single-wall galvanized ducting. The duct will
attach directly to the air collar located on the rear of the
heater, using three or four sheet metal screws (not sup­plied) equally positioned around the circumference of
the duct. The screen assembly should be removed be­fore attaching any air duct to the heater. The screws
and duct connection point must be sealed with RTV
(not supplied). TruSeal is generally used when damag­ing contaminants are present in the mechanical room.

All ducting should be self-supported.

CAUTION: Use TruSeal combustion air if damaging

airborne contaminants are or may be present in the
heater area. See Section H of this manual regarding air
contamination.

Conventional Combustion Air Supply

U.S. Installations

All Air from Inside the Building

The confined space shall be provided with TWO per-

manent openings communicating directly with an
additional room(s) of sufficient volume so that the
combined volume of all spaces meets the criteria for a
room large in comparison (NFGC). The total input of
all gas utilization equipment installed in the combined
space shall be considered in making this determination.

Each opening shall have a minimum free area of 1 in.

per 1,000 BTUH (2,225 mm
rating of all gas utilization equipment in the confined
space, but not less than 100 in.

2

per kW) of the total input

2

(645 cm2). One open­ing shall commence within 12 in. (305 mm) of the top,
and one opening shall commence within 12 in. (305
mm) of the bottom of the enclosure. The minimum
dimension of air openings shall be not less than 3 in.
(76 mm) in any direction.

All Air from Outdoors

The confined space shall communicate with the out­doors in accordance with one of the methods below.
The minimum dimension of air openings shall not be
less than 3 in. (76 mm) in any direction. Where ducts
are used, they shall be at least of the same cross­sectional area as the net free area of the openings to
which they connect.

1. Two permanent openings, one commencing

within 12 in. (305 mm) of the top, and one com­mencing within 12 in. (305 mm) of the bottom of
the enclosure, shall be provided. The openings
shall communicate directly, or by ducts, with the
outdoors or spaces (crawl or attic) that freely
communicate with the outdoors.

a. Where directly communicating with the out-

doors or where communicating to the outdoors

through vertical ducts, each opening shall

have a minimum free area of 1 in.
BTUH (550 mm

2

per kW) of total input rating

of all equipment in the enclosure.

2

per 4,000

2

10

SECTION C: Installation

b. Where communicating with the outdoors

through horizontal ducts, each opening shall

have a minimum free area of 1 in.
BTUH (1,100 mm

2

per kW) of total input rat-

2

per 2,000

ing of all equipment in the enclosure.

2. One permanent opening, commencing within 12

in. (305 mm) of the top of the enclosure, shall be
permitted where the equipment has clearances of at
least 1 in. (25 mm) from the sides and back and 6
in. (152 mm) from the front of the appliance. The
opening shall directly communicate with the out­doors or shall communicate through a vertical or
horizontal duct to the outdoors or spaces that
freely communicate with the outdoors, and shall
have a minimum free area of:

a. 1 in.

2

per 3,000 BTUH (740 mm2 per kW) of
the total input rating of all equipment located
in the enclosure, and

b. Not less than the sum of the areas of all vent

connectors in the confined space.

WARNING: Do not use the “one permanent opening”

method if the equipment room may be under negative
pressure conditions.

Canadian Installations

CAUTION: All combustion air must be drawn from

the air outside of the building; the mechanical equip­ment room must communicate directly with the
outdoors.

1. Ventilation of the space occupied by the heater

shall be provided by an opening(s) for ventilation
air at the highest practical point communicating
with the outdoors. The total cross-sectional area of
such an opening(s) shall be at least 10% of the area
required in 2. and 3. (below), but in no case shall
the cross-sectional area be less than 10 in.

2

cm

).

2. For heaters using a barometric damper in the vent

system there shall be a permanent air supply open­ing(s) having a cross section area of not less than 1

2

in.

per 7,000 BTUH (320 mm2 per kW) up to and
including 1 million BTUH, plus 1 in.
BTUH (160 mm

2

per kW) in excess of 1 million
BTUH. This opening(s) shall be either located at
or ducted to a point not more than 18 in. (450 mm)
nor less than 6 in. (152 mm) above the floor level.
The duct can also “goose neck” through the roof.
The duct is preferred to be straight down and ter-

2

(65

2

per 14,000

minated 18 in. (450 mm) from the floor, but not
near piping. This air supply opening requirement
shall be in addition to the air opening for ventila­tion air required in 1. (above).

WARNING: Care must be taken to ensure that the

equipment room is not under negative pressure
conditions.

3. For heaters not using a barometric damper in the

vent system, and when air supply is provided by
natural air flow from outdoors for a power burner
and there is no draft regulator, drafthood or similar
flue gas dilution device installed in the same space,
in addition to the opening for ventilation air re­quired in 1., there shall be a permanent air supply
opening(s) having a total cross-sectional area of
not less than 1 in.

2

mm

per kW) of total rated input of the burner(s),

2

for each 30,000 BTUH (74

and the location of the opening(s) shall not inter­fere with the intended purpose of the opening(s)
for ventilation air referred to in 1. This opening(s)
can be ducted to a point not more than 18 in. (450
mm) nor less than 6 in. (152 mm) above the floor
level. The duct can also “goose neck” through the
roof. The duct is preferred to be straight down 18
in. (450 mm) from the floor, but not near piping.

4. Refer to B149.1 for additional information.

Water Piping

General

The heater should be located so that any water leaks
will not cause damage to the adjacent area or structures.

CAUTION: This heater requires forced water circula-

tion when the burner is operating. See Table F for
minimum and maximum flow rates for water pump
selection. The pump should be interlocked with the
heater to prevent heater operation without water circu­lation.

NOTICE: Minimum pipe size for in/out connections is

2 in. NPT for 503 and 753 models and 2-½ in NPT for
1003 – 2003 models. Verify proper flow rates and ∆T
as instructed in this manual.

11

SECTION C: Installation

Relief Valve Piping

WARNING: Pressure relief valve discharge piping

must be piped near the floor and close to a drain to
eliminate the potential of severe burns. Do not pipe to
any area where freezing could occur. Refer to local
codes.

Hydrostatic Test

Unlike many types of heaters, this heater does not re­quire hydrostatic testing prior to being placed in
operation. The heat exchanger has already been fac­tory-tested and is rated for 160 psi operating pressure.
However, Raypak does recommend hydrostatic testing
of the piping connections to the heater and the rest of
the system prior to operation. This is particularly true
for hydronic systems using glycol-based antifreeze.
Raypak recommends conducting the hydrostatic test
before connecting gas piping or electrical supply.

Leaks must be repaired at once to prevent damage to
the heater. NEVER use petroleum-based stop-leak
compounds.

To perform hydrostatic test:

1. Connect fill water supply. With field-installed

bleed valve open, fill heater with water. When wa­ter flows from bleed valve, shut off water. Close
bleed valve. Carefully fill the rest of the system,
making sure to eliminate any entrapped air by us­ing high-point air vents. Close feed valve. Test at
standard operating pressure for at least 24 hours.

2. Make sure constant gauge pressure has been main-

tained throughout test.

3. Check for leaks. Repair if found.

Cold Water Operation

CAUTION: Damage due to internal condensation may

occur if the heater inlet water temperature does not
exceed 120˚F (49ºC) within 7 minutes of start-up.

This heater is equipped with a proprietary condensate
evaporation system which will evaporate any conden­sate that may begin to accumulate inside the primary
heat exchanger with water temperatures as low as
120ºF (49ºC).

Heaters operated with an inlet temperature of less than
120ºF (49ºC) MUST have a manual bypass (see Fig.

14) or an approved low-temperature operation system
to prevent problems with condensation. This piping is

like a primary/secondary boiler installation with a by­pass acting as the secondary boiler piping. Raypak
strongly recommends that thermometer(s) be placed
into the heater piping next to the in/out header to facili­tate temperature adjustment. Inlet water temperatures
below 120ºF (49ºC) can excessively cool the products
of combustion, resulting in collection of condensate in
the heat exchanger area beyond the capacity of the
condensate evaporation system.

NOTE: Vent piping MUST contain a condensate

drain which is installed according to the vent manufac­turer’s instructions and plumbed to an appropriate
condensate management system (field supplied).

Failure to reach or exceed 120ºF (49ºC) within 7 min­utes may damage or cause failure of the heat exchanger,
combustion chamber, or other parts within the combus­tion chamber. It can cause operational problems, bad
combustion, sooting, flue gas leakage and reduced ser­vice life of the vent system. A bypass allows part of the
heater discharge water to be mixed with the cooler wa­ter returning to the heater inlet to increase the heater
inlet temperature above 120ºF (49ºC). This precaution­ary measure should prevent the products of combustion
from condensing beyond the ability of the condensate
management system employed in this heater in most

installations. Warranty claims will be denied for
damage or failures caused by condensation.

Cold water operation issues are applicable to both cold
water start and cold water run applications. Cold water
operation for 7 minutes or less on initial daily start-up
is acceptable. Where cold water starts will last longer
than 7 minutes or where cold water operation is con­tinuous, provisions must be made to mix higher
temperature outlet water with the colder inlet water and
thereby raise the inlet temperature to at least 120ºF
(49ºC) within the 7-minute time limit.

Cold Water Starts

Cold water starts, wherein the inlet water temperature
remains below 120ºF (49ºC) for more than 7 minutes,

must

have cold water start protection. Known pro-

tection methods consist of mixing heated outlet water
with the inlet water with a bypass to raise the inlet to
120ºF (49ºC) or higher. Once the system is heated up
and has return water temperatures of 120ºF (49ºC) or
higher, the mixing of outlet water with inlet water is no
longer needed and the bypass can be shut off. If the
bypass is not shut off as the system heats up, the outlet
temperature may continue to climb and trip the high
limit, thereby shutting down the heater. Thus an auto-

12

SECTION C: Installation

matic valve system, such as a three-way proportional
valve or a modulating two-way valve to control the
bypass, should be utilized.

Fig. 7: Cold Water Start

Cold Water Run

Cold water run differs from cold water start in that the
system water entering the heater remains below 120ºF
(49ºC) continuously. Typically, this is the case in
swimming pool heating and water source heat pump
applications as well as some others. If the system water
is kept in a narrow temperature range of no more than
10ºF, a permanent manual bypass can be employed and
manually adjusted to achieve an inlet temperature of
120ºF (49ºC) or higher as adjusted at the minimum
temperature in this narrow temperature range (i.e.
Range 75ºF – 85ºF – adjust bypass with temperature at
75ºF) so that when temperature is 85ºF, minimum inlet

temperature would be 130ºF. An injector pump ar­rangement may also be utilized to keep the heater loop
at or above 120ºF (49ºC). An injector pump approach
has the added value of being able to adjust to changes
in the system water coming back to the heater take-off.

Fig. 8: Cold Water Run

Temperature & Pressure Gauge

The temperature and pressure gauge is shipped loose
for field installation in the outlet piping.

∆

T 30°F∆T 40°F∆T

gpm

20°F

∆

P (ft)

Model

No.

503 44 2.8 29 1.4 N/A N/A 25 1.1 35 100 11.3 9
753 65 6.4 44 3.1 33 1.9 33 1.9 40 100 13.8 13
1003 87 12.0 58 6.0 43 3.7 43 3.7 40 113 18.6 15
1252 109 20.9 73 10.2 54 6.2 54 6.2 40 113 22.2 19
1503 N/A N/A 87 16.0 65 9.5 65 9.5 40 113 25.5 23
1753 N/A N/A 102 22.5 76 13.4 76 13.4 40 113 27.2 27
2003 N/A N/A 116 31.9 87 18.9 87 18.9 40 116 32.0 30

Notes: 1. Basis for minimum flow is ∆T . Basis for maximum flow is gpm.

Min. Flow Max Flow

gpm

Table F: Heater Rates of Flow and Pressure Drops

∆

P (ft)

gpm

∆

P (ft)

gpm

∆

P (ft) ∆T

13

gpm

∆

P (ft) ∆T

SECTION C: Installation

Hydronic Heating

Pump Selection

In order to ensure proper performance of your heater
system, you must install a correctly-sized pump. Ray­pak recommends designing for a ∆T within the range
of 10°F to 40°F. See Table F for acceptable flow rates
for each model (∆T is the temperature difference be­tween the inlet and outlet water when the heater is
firing at full rate).

Feedwater Regulator

Raypak recommends that a feedwater regulator be in­stalled and set at 12 psi minimum pressure at the
highest point of the system. Install a check valve or
back flow device upstream of the regulator, with a
manual shut-off valve as required by local codes.

Piping

All high points should be vented. A heater installed
above radiation level must be provided with a low wa­ter cut-off device (sales order option F-10). The heater,
when used in connection with a refrigeration system,
must be installed so that the chilled medium is piped in
parallel with the heater with appropriate valves to pre­vent the chilled medium from entering the heater.

Three-Way Valves

Three-way valves intended to regulate system water
temperatures by reducing flow in the boiler should not
be used. Raypak heaters are high-recovery, low-mass
heaters which are not subject to thermal shock.

Fig. 10: Single Heater - Low-Temperature (Heat

Pump) Application with Primary/Secondary Piping

See Fig. 14 and instructions on page 16 for adjusting
the manual bypass.

The piping system of a hot water heater connected to
heating coils located in air handling units where they
may be exposed to circulating refrigerated air, must be
equipped with flow control valves or other automatic
means to prevent gravity circulation of the heater water
during the cooling cycle. It is highly recommended that
the piping be insulated.

Air-Separation/Expansion Tank

All heaters should be equipped with a properly sized
expansion tank and air separator fitting as shown in
Fig. 9.

Fig. 9: Air-Separation/Expansion Tank

Fig. 11: Dual Heaters (Reverse/Return)

with Primary/Secondary Piping

Domestic Hot Water

When designing the water piping system for domestic
hot water applications, water hardness should be con­sidered. Table G indicates the suggested flow rates for
soft, medium and hard water. Water hardness is ex­pressed in grains per gallon.

14

Fig. 12: Single Domestic Hot Water Heater and

Storage Tank

Potable Water and Space Heating

CAUTION: When this heater is used for both potable

water and space heating, observe the following to en­sure proper operation.

1. All piping materials and components connected to

the water heater for the space heating application
shall be suitable for use with potable water.

2. Toxic chemicals, such as used for boiler treatment,

shall not be introduced into the potable water used
for space heating.

SECTION C: Installation

3. If the heater will be used to supply potable water,

it shall not be connected to any heating system or
components previously used with a non-potable
water heating appliance.

4. When the system requires water for space heating

at temperatures higher than 140°F, a means such
as a mixing valve shall be installed to temper the
water in order to reduce scald hazard potential.

Pool Heating

When a boiler or water heater is used in a pool heating
application, ensure that all the following installation
requirements are met.

CAUTION: Power to the heater should be interlocked

with the main system pump to ensure the heater does
not fire without the main system pump in operation.
Improper flow control can damage the heater. Uncon­trolled flow (too high) or restricted flow (too low) can
seriously damage the heater. Follow these instructions
to make sure your heater is properly installed.

The MVB must be equipped with a field-supplied ex­ternal pump and bypass arrangement. This arrangement
blends outlet water with the inlet water to increase the
inlet water temperature to a minimum of 120°F,
thereby reducing the likelihood of condensation form­ing on the heat exchanger. The pump also serves to
circulate water through the heater from the main sys­tem piping.

Model

No.

Soft (0-4 grains per gallon) Medium (5-15 grains per gallon) Hard* (16-20 grains per gallon)

gpm

∆

T

∆

P

MTS SHL

gpm

∆

T

MTS SHL

∆

P

gpm

∆

T

MTS SHL

∆

P

503 17 50 3.6 2 5.9 17 50 3.6 2 5.9 9 95 10.4 2 18.1

753 26 50 4.0 2 6.3 20 65 6.4 2 10.2 13 100 13.8 2 22.2

1003 30 58 6.0 2-1/2 7.2 20 87 12.0 2-1/2 14.4 15 113 18.7 2-1/2 22.6

1253 30 73 10.4 2-1/2 12.1 20 109 21.0 2-1/2 24.6 19 113 22.3 2-1/2 26.3

1503 30 87 16.0 2-1/2 18.5 23 113 25.7 2-1/2 29.6 23 113 25.7 2-1/2 29.6

1753 30 102 22.7 2-1/2 26.0 27 113 27.4 2-1/2 31.3 27 113 27.4 2-1/2 31.3

2003 30 116 32.0 2-1/2 36.1 30 116 32.0 2-1/2 36.1 30 116 32.0 2-1/2 36.1

∆T = Temperature rise, °F
∆P = Pressure drop through heat exchanger, ft

SHL = System head loss, ft (based on heater and tank placed no more than 5 ft apart and equivalent length of 25 ft of tubing)
gpm = Gallons per minute, flow rate
MTS = Minimum tubing size

* Must use optional cupro-nickel tubes. If over 20 grains per gallon, a water softening system must also be used.

Table G: Domestic Water Heater Flow Rate Requirements

15

SECTION C: Installation

To complete the installation of the pool heater, the pool
thermostat needs to be installed in the main return wa­ter line, upstream of the heater. This will ensure that
the heater will be energized at the right time.

Fig. 13: Single Pool Heater Application

Adjustment of the manual bypass valve is critical to
proper operation of the heater. The manual bypass
valve should be adjusted to achieve a minimum inlet
water temperature of 120°F and a system supply water
temperature below 140°F. When starting with a cold
pool, make initial adjustments. Make final adjustments
when pool water approaches desired temperature.

The use of a bypass is required for proper operation in
a pool heating application. Use the following instruc­tions to set the manual bypass:

1. Turn on pump.

2. Turn on heater and wait until heater goes to full

fire.

3. With the heater operating at 100% firing rate, set

Valve A (the bypass) to ½ open position, and
Valve B to fully open position.

Fig. 14: “H” Bypass Setting

Automatic Chlorinators and Chemical
Feeders

CAUTION: Combustion air must not be contaminated

by corrosive chemical fumes which can damage the
heater and void the warranty.

All chemicals must be introduced and completely di­luted into the pool or spa water before being circulated
through the heater. Do not place chlorine tablets or
bromine sticks in the skimmer. High chemical concen­trations will result when the pump is not running (e.g.
overnight).

Chlorinators must feed downstream of the heater and
have an anti-siphoning device to prevent chemical
back-up into the heater when the pump is shut off.

NOTICE: High chemical concentrates from feeders

and chlorinators that are out of adjustment will cause
very rapid corrosion of the heat exchanger in the heater.
Such damage is not covered under the warranty.

4. Adjust Valve A until the inlet water temperature is

120°F. NOTE: Opening the valve will increase
the temperature and closing the valve will decrease
the temperature.

5. If this process does not raise the inlet water tem-

perature to 120°F and Valve A is fully open, then
slowly throttle Valve B closed to increase the inlet
water temperature to 120°F.

Winterizing Your Heater

Heaters installed outdoors as pool heaters in freezing
climate areas should be shut down for the winter. To
shut down heater, turn off manual main gas valve and
main gas shut-off. Close isolation valves. Drain the
heater using the hose bibs located on the bottom of the
heat exchanger.

16

SECTION C: Installation

NOTE: There are 2 separate drains on the MVB that

must BOTH be drained to protect the heat exchanger.
These are both accessible by removing the lower front
door from the heater. Drain any piping of all water that
may experience below-freezing temperatures.

Pool/Spa Water Chemistry

NOTICE: Chemical imbalance can cause severe dam-

age to your heater and associated equipment.

Water Hardness

Water hardness is mainly due to the presence of cal­cium and magnesium salts dissolved in the water. The
concentration of these salts is expressed in mg/l, ppm
or grains per gallon, as a measure of relative hardness
of water. Grains per gallon is the common reference
measurement used in the U.S. water heater industry.
Hardness expressed as mg/L or ppm may be divided by

17.1 to convert to grains per gallon. Water may be
classified as very soft, slightly hard, moderately hard or
hard based on its hardness number. The salts in water
will precipitate out when the water is heated and will
cause accelerated lime and scale accumulation on a
heat transfer surface.

Raypak water heaters can operate lime/scale-free using
potable water with a hardness not exceeding 20 grains
per gallon. Proper operation is achieved by setting the
temperature rise/water flow per the guidelines in the
installation instructions. If the hardness of the water
exceeds the maximum level of 20 grains per gallon
special measures must be taken to adjust flow and tem­perature rise. Water should be softened to a hardness
level no lower than 5 grains per gallon. Water softened
as low as 0 to 1 grain per gallon may be under­saturated with respect to calcium carbonate resulting in
water that is aggressive and corrosive.

pH of Water

pH is a measure of relative acidity, neutrality or alka­linity. Dissolved minerals and gases affect water’s pH.
The pH scale ranges from 0 to 14. Water with a pH of

7.0 is considered neutral. Water with a pH lower than 7
is considered acidic. Water with a pH higher than 7 is
considered alkaline. A neutral pH (around 7) is desir­able for most potable water applications. Corrosion
damage and water heater failures resulting from water
pH levels of lower than 6 or higher than 8 are non­warrantable. The ideal pH range for water used in a
storage tank or a copper water heater system is 7.2 to

7.8.

Total Dissolved Solids

Total dissolved solids (TDS) is the measure of all min­erals and solids that are dissolved in the water. The
concentration of total dissolved solids is usually ex­pressed in parts per million (ppm) as measured in a
water sample. Water with a high TDS concentration
will greatly accelerate lime and scale formation in the
hot water system. Most high TDS concentrations will
precipitate out of the water when heated. This can gen­erate a scale accumulation on the heat transfer surface
that will greatly reduce the service life of a water
heater. This scale accumulation can also impede ade­quate flow of water and may totally block the water
passages in the tubes of the heat exchanger. A heat
exchanger that is damaged or blocked by lime/scale
accumulation must be replaced. Failure of a water
heater due to lime scale build up on the heating surface
is non-warrantable. The manufacturer of the water
heater has no control of the water quality, especially
the TDS levels in your system. Total dissolved solids
in excess of 2,500 ppm will accelerate lime and scale
formation in the heat exchanger. Heat exchanger fail­ure due to total dissolved solids in excess of 2,500 ppm
is a non-warrantable condition. Raypak offers basic
temperature guidelines for operation of a potable water
heater on normal to moderate levels of hardness and
solids but levels of hardness and total dissolved solids
beyond normal limits for operation will require special
setup and operation.

NOTICE: Failure of a heat exchanger due to lime scale
build-up on the heating surface, low pH or other
chemical imbalance is non-warrantable.

Gas Supply

DANGER: Make sure the gas on which the heater will

operate is the same type as specified on the heater’s
rating plate.

Gas piping must have a sediment trap ahead of the
heater gas controls, and a manual shut-off valve lo-

cated outside the heater jacket. It is recommended that
a union be installed in the gas supply piping adjacent to
the heater for servicing. The gas supply pressure to the
heater must not exceed 10.5 in. WC for Natural Gas or

13.0 in. WC for Propane Gas. A pounds-to-inches
regulator must be installed to reduce the gas supply
pressure if it is higher than noted above. This regulator
should be placed a minimum distance of 10 times the
pipe diameter upstream of the heater gas controls.

Refer to Table H for maximum pipe lengths.

17

SECTION C: Installation

Model

No.

1” NPT 1-1/4” NPT 1-1/2” NPT 2” NPT 2-1/2” NPT

N P N P N P N P N P

503 15 35 65 150 130 360 N/A N/A N/A N/A

753 5 15 65 100 75 180 250 N/A N/A N/A

1003 N/A N/A 35 55 35 90 125 300 300 N/A

1253 N/A N/A 15 25 25 60 85 225 200 300

1503 N/A N/A 10 15 15 25 60 150 150 275

1753 N/A N/A N/A N/A N/A N/A 45 110 115 230

2003 N/A N/A N/A N/A N/A N/A 35 90 85 210

Natural Gas – 1,000 BTU/ft3, 0.60 specific gravity at 0.5 in. WC pressure drop
Propane Gas – 2,500 BTU/ft

3

, 1.53 specific gravity at 0.6 in. WC pressure drop

Table H: Maximum Equivalent Pipe Length

Gas Supply Connection

CAUTION: The heater must be disconnected from the

gas supply during any pressure testing of the gas
supply system at test pressures in excess of 1/2 psi
(3.45 kPa).

The heater must be isolated from the gas supply piping
system by closing the upstream manual shut-off valve
during any pressure testing of the gas supply piping
system at test pressures equal to or less than 1/2 psi
(3.45 kPa). Relieve test pressure in the gas supply line
prior to reconnecting the heater and its manual shut-off

valve to the gas supply line. FAILURE TO FOL-

LOW THIS PROCEDURE MAY DAMAGE THE
GAS VALVE. Over-pressurized gas valves are not

covered by warranty. The heater and its gas connec­tions shall be leak-tested before placing the appliance
in operation. Use soapy water for leak test. DO NOT
use an open flame.

CAUTION: Do not use Teflon tape on gas line pipe

thread. A pipe compound rated for use with natural and
propane gases is recommended. Apply sparingly only
on male pipe ends, leaving the two end threads bare.

CAUTION: Support gas supply piping with hangers,

not by the heater or its accessories. Make sure the gas
piping is protected from physical damage and freezing,
where required.

Gas Supply Pressure

A minimum of 4.0 in. WC and a maximum of 10.5 in.
WC upstream gas pressure is required under load and
no-load conditions for natural gas. A minimum of 4.0
in. WC and a maximum of 13.0 in. WC is required for
propane gas. The gas pressure regulator(s) supplied on
the heater is for low-pressure service. If upstream pres­sure exceeds these values, an intermediate gas pressure
regulator, of the lockup type, must be installed.

Fig. 15: Gas Supply Connection

When connecting additional gas utilization equipment
to the gas piping system, the existing piping must be
checked to determine if it has adequate capacity for the
combined load.

The gas valve pressure regulator on the heater is nomi­nally preset as noted in Table I.

18

SECTION C: Installation

Model

No.

503 -0.1

753 -0.1

1003 -0.2

1253 -0.1

1503 -0.4

1753 0.4

2003 0.6

NOTE: Manifold pressures should be + 0.2” WC.

Table I: Manifold Gas Pressure Settings

During normal operation, carbon dioxide should be 8.0
to 9.0% at full fire for natural gas and between 9.0 and

10.0% for propane gas. Carbon monoxide should be
‹100ppm.

Manifold Gas Pressure

(High Fire Values)

Natural Gas Propane Gas

-0.1

-0.1

-0.2

-0.1

-0.3

0.4

0.6

Electrical Power Connections

Installations must follow these codes:

• National Electrical Code and any other national,

state, provincial or local codes or regulations hav­ing jurisdiction.

• Safety wiring must be NEC Class 1.

• Heater must be electrically grounded as required by

the NEC.

• In Canada, CSA C22. 1 C.E.C. Part 1.

The MVB 503-1503 heaters are wired for 120 VAC, 12
amps while the MVB 1753 & 2003 heaters are wired
for 120 VAC, 18 amps. Consult the wiring diagram
shipped with the heater. Before starting the heater,
check to ensure proper voltage to the heater and pump.

If any of the original wire as supplied with the heater
must be replaced, it must be replaced with 105°C wire
or its equivalent.

Fig. 16: Rear Wiring Box Electrical Connections

All field wiring connections to the MVB heater are
made inside the rear wiring box as shown in Fig. 16.
Pump power should be taken from terminals 2 (Com),
3 (GND) and 6 (Hot) – ¾ hp and smaller ONLY.
Power to the MVB heater should be connected to ter­minals 1, 2, and 3 as noted in Fig. 16. Sensors,
interlocks, Enable/disable, and various options are
wired into terminals 1 – 12 as noted in Fig. 16.

Field-Connected Controllers

It is strongly recommended that all individually­powered control modules and the heater should be sup­plied from the same power source.

NOTICE: Field-supplied isolation relays should be
installed when field-connected controllers are mounted
more than 50 equivalent feet (18 Ga) from heater.

Boiler mounted pumps (up to ¾ hp) get their power
supply directly from the boiler power supply (connec­tions in rear wiring box). Install a circuit breaker sized
sufficiently for both the heater and the pump. Pumps
larger than ¾ hp must use a separate power supply and
run the power through the optional pump contactor
which is located in the rear wiring box (see Fig. 16).
Use appropriately-sized wire as defined by NEC, CSA
and/or local codes. All primary wiring should be 125%
of minimum rating.

Check the Power Source

WARNING: Using a multi-meter, check the following

voltages at the circuit breaker panel prior to connecting
any equipment. Make sure proper polarity is followed
and house ground is proven. (See Fig. 17.)

19

SECTION C: Installation

BLACK

ABC

Fig. 17: Wiring Connections

WHITE

CIRCUIT

BREAKER

GREEN

GROUND

Check the power source:

AC = 108 VAC Minimum, 132 VAC MAX
AB = 108 VAC Minimum, 132 VAC MAX
BC = <1 VAC Maximum

proper electrical installation are not covered by
warranty.

5. Provide overload protection and a disconnect

means for equipment serviceability as required by
local and state code.

6. Install heater controls, thermostats, or building

management systems in accordance with the appli­cable manufacturers’ instructions.

7. Conduit should not be used as the earth ground.
NOTICE: A grounding electrode conductor shall be

used to connect the equipment grounding conductors,
the equipment enclosures, and the grounded service
conductor to the grounding electrode.

Field Wiring Connection

CAUTION: Label all wires prior to disconnection

when servicing controls. Wiring errors can cause im­proper and dangerous operation. Verify proper
operation after servicing.

DANGER: SHOCK HAZARD

Make sure electrical power to the heater is discon­nected to avoid potential serious injury or damage to
components.

Fig. 18: Multi-meter

Making the Electrical Connections

Refer to Fig. 16-19.

1. Verify that circuit breaker is properly sized by

referring to heater rating plate. A dedicated circuit
breaker should be provided.

2. NOTE: Current draw noted on rating plate does

not include pump current.

3. Turn off all power to the heater. Verify that power

has been turned off by testing with a multi-meter
prior to working with any electrical connections or
components.

4. Observe proper wire colors while making electri-

cal connections. Many electronic controls are
polarity sensitive. Components damaged by im-

Fig. 19: Wiring Location

20

SECTION C: Installation

Venting

CAUTION: Proper installation of flue venting is criti-

cal for the safe and efficient operation of the heater.

General

Appliance Categories

Heaters are divided into four categories based on the
pressure produced in the exhaust and the likelihood of
condensate production in the vent.

Category I – A heater which operates with a non-

positive vent static pressure and with a vent gas tem­perature that avoids excessive condensate production in
the vent.

Category II – A heater which operates with a non-

positive vent static pressure and with a vent gas tem­perature that may cause excessive condensate
production in the vent.

Category III – A heater which operates with a positive

vent pressure and with a vent gas temperature that
avoids excessive condensate production in the vent.

Category IV – A heater which operates with a positive

vent pressure and with a vent gas temperature that may
cause excessive condensate production in the vent.

See Table J for appliance category requirements.

Note: For additional information on appliance catego­rization, see appropriate ANSI Z21 Standard and the
NFGC (U.S.), or B149.1 (Canada), or applicable provi­sions of local building codes.

CAUTION: Condensate drains for the vent piping are

required for installations of the MVB. Follow vent
manufacturer instructions for installation and location
of condensate drains in the vent. Condensate drain
must be primed with water to prevent gas flue leak and
must be routed to an appropriate container for neutrali­zation before disposal, as required by local codes.

WARNING: Contact the manufacturer of the vent

material if there is any question about the appliance
categorization and suitability of a vent material for
application on a Category IV vent system. Using im­proper venting materials can result in personal injury,
death or property damage.

Use only the special gas vent pipes listed for use with
Category IV gas burning heaters, such as the AL29-4C
stainless steel vents offered by Heat Fab Inc. (800-772-

0739), Protech System, Inc. (800-766-3473) or Z-Flex
(800-654-5600). Pipe joints must be positively sealed.
Follow the vent manufacturer’s installation instructions
carefully.

Support of Vent Stack

The weight of the vent stack or chimney must not rest
on the heater vent connection. Support must be pro­vided in compliance with applicable codes. The vent
should also be installed to maintain proper clearances
from combustible materials.

Use insulated vent pipe spacers where the vent passes
through combustible roofs and walls.

Combustion

Air Supply

From Inside Building
(Non-Direct Venting)

From Outside Building

(Direct Venting)

Exhaust

Configuration

Vertical

Venting

Horizontal Through-

the-Wall Venting

Vertical

Venting

Horizontal Through-

the-Wall Venting

Table J: Venting Category Requirements

Heater Venting

Category

IV

21

Certified

Materials

Stainless Steel

AL29-4C

Combustion Air

Inlet Material

Galvanized Steel

PVC
ABS

CPVC

SECTION C: Installation

Vent Terminal Location

NOTICE: During winter months check the vent cap

and make sure no blockage occurs from build-up of
snow or ice.

1. Condensate can freeze on the vent cap. Frozen

condensate on the vent cap can result in a blocked
flue condition.

2. Give special attention to the location of the vent

termination to avoid possibility of property dam­age or personal injury.

3. Gases may form a white vapor plume in winter.

The plume could obstruct a window view if the
termination is installed near windows.

4. Prevailing winds, in combination with below-

freezing temperatures, can cause freezing of con­densate and water/ice build-up on buildings, plants
or roofs.

5. The bottom of the vent terminal and the air intake

shall be located at least 12 in. above grade, includ­ing normal snow line.

6. Un-insulated single-wall Category IV metal vent

pipe shall not be used outdoors in cold climates for
venting gas-fired equipment without insulation.

7. Through-the-wall vents for Category IV appli-

ances shall not terminate over public walkways or
over an area where condensate or vapor could cre­ate a nuisance or hazard or could be detrimental to
the operation of regulators, relief valves, or other
equipment.

8. Locate and guard vent termination to prevent acci-

dental contact by people or pets.

U.S. Installations

Refer to the latest edition of the National Fuel Gas
Code.

Vent termination requirements are as follows:

1. Vent must terminate at least 4 ft below, 4 ft hori-

zontally from or 1 ft above any door, window or
gravity air inlet to the building.

2. The vent must not be less than 7 ft above grade

when located adjacent to public walkways.

3. Terminate vent at least 3 ft above any forced air

inlet located within 10 ft.

4. Vent must terminate at least 4 ft horizontally, and

in no case above or below unless 4 ft horizontal
distance is maintained, from electric meters, gas
meters, regulators, and relief equipment.

5. Terminate vent at least 6 ft away from adjacent

walls.

6. DO NOT terminate vent closer than 5 ft below

roof overhang.

7. The vent terminal requires a 12 in. vent terminal

clearance from the wall.

8. Terminate vent at least 1 ft above grade, including

normal snow line.

9. Multiple direct vent installations require a 4 ft

clearance between the ends of vent caps located on
the same horizontal plane.

Canada Installations

Refer to latest edition of B149.1.

9. DO NOT terminate vent in window well, stairwell,

alcove, courtyard or other recessed area.

10. DO NOT terminate above any door, window, or

gravity air intake. Condensate can freeze, causing
ice formations.

11. Locate or guard vent to prevent condensate from

damaging exterior finishes. Use a rust-resistant
sheet metal backing plate against brick or masonry
surfaces.

12. DO NOT extend exposed vent pipe outside of

building beyond the minimum distance required
for the vent termination. Condensate could freeze
and block vent pipe.

A vent shall not terminate:

1. Directly above a paved sidewalk or driveway

which is located between two single-family dwell­ings and serves both dwellings.

2. Less than 7 ft (2.13 m) above a paved sidewalk or

paved driveway located on public property.

3. Within 6 ft (1.8 m) of a mechanical air supply inlet

to any building.

4. Above a meter/regulator assembly within 3 ft (0.9

m) horizontally of the vertical centre-line of the
regulator.

22

SECTION C: Installation

5. Within 6 ft (1.8 m) of any gas service regulator

vent outlet.

6. Less than 1 ft (305 mm) above grade level.

7. Within 3 ft (0.9 m) of a window or door which can

be opened in any building, any non-mechanical air
supply inlet to any building or the combustion air
inlet of any other appliance.

8. Underneath a verandah, porch or deck, unless the

verandah, porch or deck is fully open on a mini­mum of two sides beneath the floor, and the
distance between the top of the vent termination
and the underside of the verandah, porch or deck is
greater than 1 ft (305 mm).

Venting Installation Tips

Support piping:

• horizontal runs - at least every 5 ft

• vertical runs - use braces

• under or near elbows

WARNING: Examine the venting system at least once

a year. Check all joints and vent pipe connections for
tightness, corrosion or deterioration.

Venting Configurations

For heaters connected to gas vents or chimneys, vent
installations shall be in accordance with Part 7, Venting
of Equipment, of the NFGC (U.S.), or B149.1 (Canada),
or applicable provisions of local building codes.

Vertical Venting (Category IV)

CAUTION: This venting system requires the installa-

tion of a condensate drain in the vent piping per the
vent manufacturer’s instructions. Failure to install a
condensate drain in the venting system will void all
warranties on this heater.

Installation

The maximum and minimum venting length for this
Category IV appliance shall be determined per the
NFGC (U.S.) or B149.1 (Canada).

The diameter of vent flue pipe should be sized accord­ing to Part 11 of the NFGC (U.S.) and Part 7 and
Appendix B of B149.1 (Canada). The minimum flue
pipe diameter for conventional venting using Category
IV, stainless steel AL29-4C vent is: 6 in. for Models
503-1003; and 8 in. for Models 1253-2003.

NOTICE: A vent adapter (field-supplied) may be re-

quired to connect the Category IV vent to the heater.

The connection from the appliance vent to the stack
must be as direct as possible and shall be the same di­ameter as the vent outlet. The horizontal breaching of a
vent must have an upward slope of not less than 1/4
inch per linear foot from the heater to the vent terminal.
The horizontal portions of the vent shall also be sup­ported for the design and weight of the material
employed to maintain clearances and to prevent physi­cal damage or separation of joints.

Certified

Model

Vent

Material

503 15*

753 75

1003

1253 40

Category IV

(AL29-4C)

1503 75

1753 75

2003

* Vent length may be extended up to 40 ft. using a barometric damper installed at 15 equivalent feet from the heater where the category of the

vent changes from Cat IV to Cat II. NOTE: Special vent materials are still required.

1

Vent lengths are based on a lateral length of 2 ft. Refer to the latest edition of the NFGC for further details.

** Subtract 10 ft per elbow. Max. 4 elbows.

Vent Size

(in.)

Vertical Vent

Height

1

(Ft)

Min. Max.

Combustion Air

6

75

Galvanized Steel,

0

8

75

Table K: Category IV Vertical Venting

23

Intake Pipe

Material

PVC,
ABS,

CPVC

Air Inlet

Max. Length** (Ft)

6” Ø 8” Ø 10” Ø

45 100 N/A

N/A 45 85

SECTION C: Installation

f

Termination

The vent terminal should be vertical and should termi­nate outside the building at least 2 ft above the highest
point of the roof within 10 ft. The vent cap should have
a minimum clearance of 4 ft horizontally from and in
no case above or below (unless a 4 ft horizontal dis­tance is maintained) electric meters, gas meters,
regulators and relief equipment. The distance of the
vent terminal from adjacent public walkways, adjacent
buildings, open windows and building openings must
be consistent with the NFGC (U.S.) or B149.1 (Can­ada). Gas vents supported only by flashing and
extending above the roof more than 5 ft should be se­curely braced to withstand snow and wind loads.

CAUTION: A listed vent cap terminal suitable for
connection to the Cat IV vent materials, adequately
sized, must be used to evacuate the flue products from
the heaters.

Common Venting

The NFGC does not address sizing guidelines for the
common venting of multiple Category IV heaters. This
is covered in the NFGC under “Engineered Vent Sys­tems”. Table L provides boiler discharge vent pressures
at vent pressure switch and volumes of flue products at
full fire for the calculation of appropriate vent sizing
for common venting.

WARNING: Vent connectors serving any other appli­ances shall not be connected into any portion of
mechanical draft systems operating under a positive
pressure. If an MVB heater is installed to replace an
existing heater, the vent system MUST be verified to
be of the correct size and of Category IV AL29-4C
vent material construction. If it is NOT, it MUST be
replaced.

NOTE: For extractor sizing, typical CO

8.5% for natural gas and 9.5% for LP gas and flue tem­perature of 300° F.

Vent
Pressure
(in. WC)

Model

Vent Size

(in.)

503 0.1 160
753 0.2 240
1003

6

0.3 320
1253 0.2 400
1503 0.3 480

8

1753 0.4 560
2003

* NOTE: Data for 100% firing rate.

0.5 640

levels are

2

Volume o

Flue Products

(CFM)

Fig. 20: Vertical Venting

Table L: Vent Pressure and Volume of

Flue Products Data

24

SECTION C: Installation

Fig. 21: Typical Common Venting

Horizontal Through-the-Wall Direct
Venting (Category IV)

Fig. 22: Horizontal Through-the-Wall Venting

Fig. 23: Alt. Horizontal Through-the-Wall Venting

NOTE: While a drain connection is required in the
vent of all MVB installations, the drain can be ac­complished in several different ways. The figures in
this manual show the drain in a vent tee, however,
this can also be accomplished using an inline collec­tor for condensing stacks or an inline vertical or
horizontal collector available from several of the
listed vent manufacturers.

25

SECTION C: Installation

Fig. 24: Horizontal Through-the-Wall Direct Venting

CAUTION: This venting system requires the installa-

tion of a condensate drain in the vent piping per the
vent manufacturer’s instructions. Failure to install a
condensate drain in the venting system will void all
warranties on this heater.

Installation

These installations utilize the heater-mounted blower to
vent the combustion products to the outdoors. Com­bustion air is taken from inside the room and the vent is

installed horizontally through the wall to the outdoors.
Adequate combustion and ventilation air must be sup­plied to the equipment room in accordance with the
NFGC (U.S.) or B149.1 (Canada).

The total length of the horizontal through-the-wall flue
system should not exceed 75 equivalent ft in length. If
horizontal run exceeds 75 equivalent ft, an appropri­ately sized variable-speed extractor must be used. Each
elbow used is equal to 10 ft of straight pipe. This will
allow installation in one of the four following arrange­ments:

• 75’ of straight flue pipe

• 65’ of straight flue pipe and one elbow

• 55’ of straight flue pipe and two elbows

• 45’ of straight pipe and three elbows

The vent cap is not considered in the overall length of
the venting system.

The vent must be installed to prevent flue gas leakage.
Care must be taken during assembly to ensure that all
joints are sealed properly and are airtight. The vent
must be installed to prevent the potential accumulation
of condensate in the vent pipes. It is required that:

1. The vent must be installed with a condensate drain

located in proximity to the heater as directed by
the vent manufacturer.

2. The vent must be installed with a slight upward

slope of not less than 1/4 inch per foot of horizon­tal run to the vent terminal.

Model

Certified Vent

Material

Vent Size

(in.)

503

753

1003

1253

Category IV

(AL29-4C)

1503

1753

2003

* Vent lengths are based on a lateral length of 2 ft. Refer to the latest edition of the NFGC for further details.

** Subtract 10 ft per elbow. Max. 4 elbows.

Table M: Category IV Horizontal Vent & Horizontal Direct Vent

Horizontal

Vent Length (Ft)*

Min. Max.

Combustion Air

Intake Pipe

Material

Air Inlet

Max. Length (Ft) **

6”Ø 8” Ø 10” Ø

6 45 100 N/A

Galvanized Steel,

0 75

8

PVC,
ABS,

CPVC

N/A 45 85

26

SECTION C: Installation

3. The vent must be insulated through the length of

the horizontal run.

Termination

The flue direct vent cap MUST be mounted on the ex­terior of the building. The direct vent cap cannot be
installed in a well or below grade. The direct vent cap
must be installed at least 1 ft above ground level and
above normal snow levels. The Raypak-approved
stainless steel flue direct vent cap must be used (sales
order option D-15). The vent terminal must be located
NO CLOSER than 12” off the wall.

WARNING: No substitutions of flue pipe or vent cap

material are allowed. Such substitutions would jeopard­ize the safety and health of inhabitants.

Direct Vent - Vertical

arrangement that does not exceed the lengths shown in
Table K.

The vent cap is not considered in the overall length of
the venting system.

Care must be taken during assembly that all joints are
sealed properly and are airtight.

The vent must be installed to prevent the potential ac­cumulation of condensate in the vent pipes. It is
required that:

1. The vent must be installed with a condensate drain

located in proximity to the heater as directed by
the vent manufacturer.

2. The vent must be installed with a slight upward

slope of not more than 1/4 inch per foot of hori­zontal run to the vent terminal.

3. The vent must be insulated through the length of

the horizontal run.

Termination

The vent cap MUST be mounted on the exterior of the
building. The vent cap cannot be installed in a well or
below grade. The vent cap must be installed at least 1 ft
above ground level and above normal snow levels.

Fig. 25: Direct Vent - Vertical

CAUTION: This venting system requires the installa-

tion of a condensate drain in the vent piping per the
vent manufacturer’s instructions. Failure to install a
condensate drain in the venting system will void all
warranties on this heater.

Installation

These installations utilize the heater-mounted blower to
draw combustion air from outdoors and vent combus­tion products to the outdoors.

The total length of air supply pipe cannot exceed the
distances listed in Table K. Each elbow used is equal to
10 ft of straight pipe. This will allow installation in any

The vent cap MUST NOT be installed with any com­bustion air inlet directly above a vent cap. This vertical
spacing would allow the flue products from the vent
cap to be pulled into the combustion air intake installed
above.

This type of installation can cause non-warrantable
problems with components and poor operation of the
heater due to the recirculation of flue products. Multi­ple vent caps installed in the same horizontal plane
must have a 4 ft clearance from the side of one vent
cap to the side of the adjacent vent cap(s).

Combustion air supplied from outdoors must be free of
particulate and chemical contaminants. To avoid a
blocked flue condition, keep the vent cap clear of snow,
ice, leaves, debris, etc.

WARNING: No substitutions of flue pipe or vent cap

material are allowed. Such substitutions would jeopard­ize the safety and health of inhabitants.

The stainless steel flue direct vent cap must be fur­nished by the heater manufacturer in accordance with
its listing (sales order option D-15).

27

SECTION C: Installation

Outdoor Installation

Outdoor models are self-venting when installed with
the optional factory-supplied outdoor vent kit. Addi­tional vent materials are required as outlined in the
Outdoor Vent Kit instructions. A special vent cap and
air intake elbow are offered in accordance with CSA
requirements. These must be installed directly on the
vent pipe as illustrated in Fig. 26.

Care must be taken when locating the heater outdoors,
because the flue gases discharged from the vent cap
can condense as they leave the cap. Improper location
can result in damage to adjacent structures or building
finish. For maximum efficiency and safety, the follow­ing precautions must be observed:

1. Outdoor models must be installed outdoors. They

must use the outdoor vent cap and air intake elbow
available from the manufacturer (sales order op­tion D-11).

2. Periodically check the venting system. The

heater’s venting areas must never be obstructed in
any way and minimum clearances must be ob­served to prevent restriction of combustion and
ventilation air. Keep area clear and free of com­bustible and flammable materials.

3. Do not locate adjacent to any window, door walk-

way, or gravity air intake. The vent must be
located a minimum of 4 ft horizontally from such
areas.

4. Install above grade level and above normal snow

levels.

5. Vent terminal must be at least 3 ft above any

forced air inlet located within 10 ft.

6. Adjacent brick or masonry surfaces must be pro-

tected with a rust-resistant sheet metal plate.

NOTICE: Condensate can freeze on the vent cap. Fro-

zen condensate on the vent cap can result in a blocked
flue condition.

NOTICE: The vent cap and air intake hood must be

furnished by the heater manufacturer in accordance
with its listing (sales order option D-11).

Fig. 26: Outdoor Venting

Freeze Protection

When installing this heater in an outdoor location that
is susceptible to freezing, sales option B-22 should be
installed to energize the heater pump at a present out­door air temperature and circulate water to reduce the
possibility of freezing and damage to the heat ex­changer or headers.

Controls

WARNING: Installation, adjustment and service of

heater controls, including timing of various operating
functions, must be performed by a qualified installer,
service agency or the gas supplier. Failure to do so may
result in control damage, heater malfunction, property
damage, personal injury, or death.

WARNING: Turn off the power to the heater before

installation, adjustment or service of any heater con­trols. Failure to do so may result in heater malfunction,
property damage, personal injury, or death.

CAUTION: This appliance has provisions to be con-

nected to more than one supply source. To reduce the
risk of electric shock, disconnect all such connections
before servicing.

CAUTION: Risk of electric shock: More than one

disconnect switch may be required to de-energize the
equipment before servicing.

28

SECTION C: Installation

The Raypak modulating temperature control is pro­vided to maintain the desired system water temperature.
The control has various modes of operation which are
listed below.

Operating Modes

Mode 1 – Setpoint operation using parallel piping. The
heater outlet water temperature is controlled to the
boiler target setpoint.

Mode 2 – Setpoint operation using primary / secondary
piping. The control modulates the heater to satisfy a
remote header sensor. The heater is turned off based on
boiler max and boiler differential (factory default H7
boilers).

Mode 3 – Dedicated DHW operation using parallel
piping. A call for heat is determined by the DHW sen­sor. The heater outlet water is controlled to the boiler
target temperature (factory default WH7 water heaters).

Mode 4 – Outdoor reset and reset override operation
using parallel piping. The heater is operated as in Mode

1. However the target temperature is based on outdoor
reset. The outdoor reset temperature can be remotely
overridden.

BOIL MIN - Lowest outlet water temperature that the

control is allowed to use as a target temperature

BOIL ON - Accumulated runtime of heater (up to 999

hours, then resets to 0)

BOIL OUT - Actual heater outlet water temperature
BOIL START - Starting boiler water temperature
BOIL SUP - Actual system supply water temperature
BOIL TARGET - Target temperature that the heater is

trying to maintain

‘BURNER’ DELAY - Heater delay from the start of

the ignition sequence until it fires

DIFF - The operating differential of the heater; The

heater outlet water temperature is allowed to rise above
the BOIL TARGET temperature by 1/2 of this differ­ential before the heater shuts off

MODE - Operating mode of the heater
OUTDR - Outdoor air temperature
OUTDR DESIGN - Design outdoor air temperature

used in the heat loss calculation

Mode 5 – Outdoor reset and reset override operation
using primary/secondary piping. The heater is operated
as in Mode 2. However, the target temperature is based
on outdoor reset. The outdoor reset temperature can be
remotely overridden.

Mode 6 – This mode is used for remote control mode.
The Boil Max setting is the heater shutdown tempera­ture.

Definitions

The following items are common to Modes 1 thru 5.
They are not required for Mode 6 – the mode for exter­nal heater control.

% OUT - Current percent modulation rate of heater
BOIL DSGN - Design boiler water temperature used

in heat loss calculations

BOIL MASS - This setting allows adjustment in the

field for high or low thermal masses; High thermal
mass (setting=3) provides slower reaction, lower ther­mal mass (setting=1) provides faster reaction

BOIL MAX - Highest outlet water temperature that

the control is allowed to use as a target temperature

OUTDR START - Starting outdoor air temperature
PUMP DLY - Sets the operating time of the pump

once the CFH is satisfied

TANK - Current DHW tank temperature (Mode 3)
TANK DIFF - Storage tank differential (Mode 3)
TANK TARGET - Target temperature in the DHW

storage tank (Mode 3)

UNITS - Selects the temperature units to be displayed

o

(

F or oC). For example, if the heater target temperature
is set to 160°F and the differential is set to 10°F, on
temperature rise, the heater will shut off at 165
Once the heater shuts off, it will not come on again
until the temperature falls to 155

o

F.

o

F.

WWSD - Selects the outdoor temperature that shuts

the heater off, no matter what the demand. NOTE: The
WWSD segment is displayed on the LCD.

Operation

The Raypak modulating temperature control uses a
Liquid Crystal Display (LCD) as a method of supply­ing information. The LCD is used to setup and monitor

29

SECTION C: Installation

system operation by means of three push buttons (Item,
▲,▼). Item advances the display, while ▲,▼are used
in the adjust menu.

2 seconds, then the software version is displayed for 2
seconds. At the end of that 4 second period, the control
enters the normal operating mode and “VIEW” is dis­played. Pressing the scroll button “scrolls” through the
displayed values in the “VIEW” menu.

Fig. 27: Modulating Temperature Control

User Interface

All items displayed by the control are organized into
two menus, the view menu and the adjust menu. The
active menu is displayed in the upper right hand side of
the display in the menu field. The default menu is the
view menu.

When the modulating temperature control is powered
up, the control turns on all segments in the display for

Item Modes

Fig. 28: Modulating Temperature Control Display

Default

Range

Boiler Water Heater

BOIL TARGET 1, 2

3

4, 5

BOIL MAX 1, 2, 4, 5, 6

3

140 ºF

---

180 ºF

200 ºF

---

---

160 ºF

---

---

180 ºF

OFF, 70 – 220 ºF
OFF, 70 – 200 ºF
OFF, 70 – 220 ºF

120 – 225 ºF, OFF
120 – 200 ºF, OFF

BOIL MIN 1 - 5 135 ºF 135 ºF OFF, 80 – 180 ºF

‘BURNER’ DELAY 1 - 5 1:30 1:30 0:00 to 3:00 Min.

BOIL MASS 1 - 5 1 1 1 (Low), 2 (Med), 3 (High)

DIFF 1 - 5 10 ºF 10 ºF 2 – 42 ºF

TANK TARGET 3 --- 120 ºF OFF, 70 – 190 ºF

TANK DIFF 3 --- 5 ºF 2 – 10 ºF

PUMP DLY All 3:00 3:00 OFF, 0:20 to 9:55 Min., ON

OUTDR START 4, 5 70 ºF --- 35 – 85 ºF

OUTDR DSGN 4, 5 -10 ºF --- -40 – 32 ºF

BOIL START 4, 5 135 ºF --- 35 – 150 ºF

BOIL DSGN 4, 5 180 ºF --- 70 – 220 ºF

WWSD 4, 5 70 ºF --- 35 – 100 ºF, OFF

UNITS All ºF ºF ºF or ºC

MODE --- 2 3 1, 2, 3, 4, 5, 6

Table N: Modulating Temperature Control Default Setpoints

30

SECTION C: Installation

To make an adjustment to a setting in the control, begin
by selecting the “ADJUST” menu. To change from the
view menu to the adjust menu, simultaneously press
and hold all three buttons for 1 second. The menu
name, “ADJUST” will be displayed in the menu field.

The menu will automatically revert back to the view
menu after 20 seconds of keyboard inactivity. Then
scroll to the desired item using the scroll button. Fi­nally, use the ▲or ▼ button to make the adjustment.

In the absence of other information, the values pro­vided in Table N should be used as default settings.

Heater Sequence of Operation

Model 503 - 1503

1. The black (hot) wire lead, located at the right-

middle front inside the control compartment, goes
directly to the main power switch.

2. When the main power switch is placed in the

“ON” position, the 120 VAC terminal block in the
control compartment, the N.O. contacts of pump
relay, the N.O. contacts of blower relay, the
120/24 VAC transformer, and terminals L1 and F1
of the ignition module are powered.

3. The 120/24 VAC transformer sends a 24 VAC hot

power signal to the 24V Terminal Block .

4. 24 VAC is sent from the 24V Terminal Block to

the NO pump contacts on the modulating tempera­ture control (pin #13), to pin TP2 of the optional
alarm relay, to terminal R of the alarm circuit on
the modulating temperature control (pin #24) and
the green “Power On” LED on the front of the
heater will illuminate.

5. 24 VAC power is sent from 24V Terminal Block

to Pin P1-1 of the UDB board, the 24 VAC termi­nal of the ignition control module, the NC contact
of the manual high limit, and L1 of the Low Water
Cut Off (if equipped).

24 VAC is sent from the NC contacts of the man­ual high limit to pin P3-1 & P3-2 of the UDB
board.

Upon loss of water in the heater, the Low Water
Cut Off (if equipped) will send a 24 VAC signal to
pin P3-4 of the UDB board to indicate a safety
fault.

6. A 24 VAC signal is sent from the NO contacts of

the Low Water Cut Off to the common terminal of
the Blocked Vent Switch.

During a blocked vent condition a 24 VAC signal
is sent from the NO open contacts of the Blocked
Vent Switch to pin P3-5 of the UDB board to indi­cate a safety fault.

7. During normal operation of the heater the 24 VAC

signal exits the NC contacts of the Blocked Vent
Switch and is sent to the common terminal, of the
Low Gas Pressure Switch (if equipped).

During a low gas pressure condition 24 VAC is
sent from the NC contacts of the Low Gas Pres­sure Switch to pin P3-6 of the UDB board to
indicate a safety fault.

8. 24 VAC is sent from the NO contacts of the Low

Gas Pressure Switch to the common terminal of
the High Gas Pressure Switch (if equipped).

During a high gas pressure condition 24 VAC is
sent from the NO contacts of the High Gas Pres­sure Switch to pin P3-7 of the UDB board to
indicate a safety fault.

9. 24 VAC is sent from the NC contacts of the High

Gas Pressure Switch to the common terminal of
the Auto Reset High Limit (if equipped) and to en­ergize the coil of optional alarm relay.

If the Auto Hi Limit opens, 24 VAC is sent from
the NO contacts of the Auto Hi Limit to pin P3-3
of the UDB board to indicate a safety fault.

10. 24 VAC is sent from the NC contacts of the Auto

Reset Hi Limit to the common terminal of time de­lay relay.

11. 24 VAC is sent from the NC contacts of time delay

relay to the common terminal of the burner switch
located on the front exterior panel of the heater.

12. Power then travels to the enable/disable connec-

tion and to the Ht D (heat demand) connection of
the modulating temperature control.

Power splits from the enable/disable and goes to
the stage contact of the modulating temperature
control (pin #15).

13. When the stage contact closes on the modulating

temperature control, 24 VAC is sent to the com­mon terminal of the flow switch and to pin P1-3

31

SECTION C: Installation

(CFH) of the UDB board. In addition, the amber
“Call-for-Heat” LED on the front of the heater will
illuminate.

14. The pump contact on the modulating temperature

control closes sending 24 VAC to the pump switch
located on the front exterior panel of the heater.

15. When the pump switch is closed, 24 VAC is sent

to the coil of the pump relay.

16. The pump relay energizes and closes the contacts,

starting the heater pump.

17. Upon sufficient flow, the flow switch closes and

sends 24 VAC to the common terminal of the air
pressure switch, TH terminal of the ignition mod­ule, coil of the ignition lockout relay and the NO
contacts of the ignition lockout relay.

If the flow switch does not close, a 24 VAC signal
is sent to pin P4-9 of the UDB board to indicate an
insufficient flow condition.

When the 24 VAC signal is sent to P4-9 the same
signal then de-energizes the coil of time delay re­lay to remove a heat demand from the modulating
temperature control and restart the ignition se­quence after the 5 second time delay.

Upon ignition lockout, the module energizes the
ignition lockout relay and sends a 24 VAC signal
to pin P4-12 (ignition lockout) of the UDB board.

18. When 24 VAC is received at TH on the ignition

module, the contacts between pins F1 and F2 close
and send 120 VAC to pin 1 of the blower relay.

19. The coil of the blower relay energizes closing the

NO contacts sending 120 VAC to energize the
combustion air blower motor.

The combustion air blower will operate at 50% of
capacity for approximately ninety (90) seconds be­fore the modulating signal from the modulating
temperature control will control the fan speed in
relationship to the system water temperature.

20. Once sufficient air pressure is achieved in the

heater and the air pressure switch closes the NO
contacts, 24 VAC is sent to the heater interlock
connection on the ignition module.

contacts of the air pressure switch to pin P4-10 of
the UDB board to indicate insufficient air pressure.

When the 24 VAC signal is sent to P4-10 the same
signal then de-energizes the coil of the time delay
relay to remove a heat demand from the modulat­ing temperature control and restart the ignition
sequence after the 5 second time delay.

21. After receiving 24 VAC at the heater interlock,

power then travels to the P Switch terminal of the
ignition module.

The ignition module employs a 15 second pre­purge before the next sequence.

22. After 15 seconds of combustion chamber pre-

purge, pin S1 sends 120 VAC to the Hot Surface
Igniter.

23. The Hot Surface Igniter will be energized for ap-

proximately 30 seconds and must exceed 3.1 amp
draw during heat up.

24. Once the ignition module determines the proper

operation of the Hot Surface Igniter, a 24 VAC
signal is output from the Valve pin on the module
to energize the gas valve.

25. The gas valve is energized and the blue “Burner

On” LED on the front of the heater energizes.

26. The remote sensor is now trying to rectify the

flame. If the flame is not rectified within 4 seconds,
the ignition module will shut down the gas valve
and lock out.

27. When burner flame is rectified, the gas valve will

remain at 50% fire for the remainder of the ninety
(90) second delay after the CFH was initiated and
then modulate in relationship to the output signal
to the combustion air blower from the modulating
temperature control.

28. When the CFH is satisfied, the heater will return to

a standby condition awaiting the next CFH.

Model 1753 – 2003

1. The black (hot) wire lead, located at the right-

middle front inside the control compartment, goes
directly to the main power switch.

If air pressure is insufficient or lost during heater
operation a 24 VAC signal is sent from the NC

2. When the main power switch is placed in the

“ON” position, the 120 VAC terminal block in the
control compartment, the N.O. contacts of the

32

SECTION C: Installation

pump relay and the blower receives power but
does not energize at this time and terminal L1 the
ignition module is powered.

3. The 120/24 VAC transformer sends a 24 VAC hot

power signal to the 24V Terminal Block.

4. 24 VAC is sent from the 24V Terminal Block to

pin L1 of the Low Water Cut Off, the 24 VAC
terminal of the ignition control module, the green
LED on the front of the heater to signify “Power
On”, terminal R (pin #24) of the modulating tem­perature control, the NC contacts of the manual
high limit, pin P3-1 of the UDB board, pin P1-1 of
the UDB board, pin J5-5 of the UGB board, the
NC contacts of the alarm relay, the red LED on the
front of the heater to signify “Service” if in alarm
mode and the NO pump contacts on the tempera­ture controller.

24 VAC is sent from the NC contacts of the man­ual high limit to pin P3-2 of the UDB board and to
the common terminal of the Low Water Cut Off (if
equipped).

Upon loss of water in the heater, the Low Water
Cut Off will send a 24 VAC signal to pin P3-4 of
the UDB board to indicate a safety fault.

5. A 24 VAC signal is sent from the NO contacts of

the Low Water Cut Off to the common terminal of
the Blocked Vent Switch.

During a blocked vent condition a 24 VAC signal
is sent from the NO open contacts of the Blocked
Vent Switch to Pin P3-5 of the UDB board to indi­cate a safety fault.

6. During normal operation of the heater, the 24

VAC signal will exit the NC contacts of the
Blocked Vent Switch and is sent to the common
terminal, of the Low Gas Pressure Switch (if
equipped).

sure Switch to Pin P3-7 of the UDB board to
indicate a safety fault.

8. 24 VAC is sent from the NC contacts of the High

Gas Pressure Switch to energize the alarm relay
coil and to the common terminal of the Auto Reset
High Limit (if equipped).

If the Auto Hi Limit opens, a 24 VAC is sent to
Pin P3-3 of the UDB board to indicate a safety
fault.

9. 24 VAC is sent from the NC contacts of the Auto

Reset Hi Limit to the common terminal of time de­lay relay.

10. 24 VAC is sent from the NC contacts of time delay

relay to the common terminal of the burner switch
located on the front exterior panel of the heater.

11. Power then travels to the enable/disable connec-

tion and to the Ht D (heat demand) connection of
the modulating temperature control.

Power splits from the enable/disable and goes to
the stage contact of the modulating temperature
control.

12. When the stage contact closes on the modulating

temperature control, 24 VAC is sent to the com­mon terminal of the flow switch and to pin P1-3
(CFH) of the UDB board. 24 VAC is now sent di­rectly to the amber LED on the front of the heater
to signify a “Call For Heat”.

13. The pump contact on the modulating temperature

control closes sending 24 VAC to the pump switch
located on front exterior panel of the heater.

14. When the pump switch is closed 24 VAC is sent to

the coil of the pump relay.

15. The pump relay energizes and closes the contacts,

starting the heater pump.

During a low gas pressure condition, 24 VAC is
sent from the NC contacts of the Low Gas Pres­sure Switch to Pin P3-6 of the UDB board to
indicate a safety fault.

7. 24 VAC is sent from the NO contacts of the Low

Gas Pressure Switch to the common terminal of
the High Gas Pressure Switch (if equipped).

During a high gas pressure condition, 24 VAC is
sent from the NO contacts of the High Gas Pres-

16. Upon sufficient flow, the flow switch closes and

sends 24 VAC to the common terminal of the air
pressure switch, the lockout relay coil and the NO
contacts of the lockout relay. A 24 VAC signal is
also sent from the common terminal of the air
pressure switch to pin F1 of the ignition module.

If the flow switch does not close, a 24 VAC signal
is sent to pin P4-9 of the UDB board to indicate an
insufficient flow condition.

33

SECTION C: Installation

When the 24 VAC signal is sent from the flow
switch to P4-9, the same signal then de-energizes
the coil of the time delay relay to remove a heat
demand from the modulating temperature control
and restart the ignition sequence after the five­second time delay.

Upon ignition lockout, the module energizes the
lockout relay and sends a 24 VAC signal to pin
P4-12 (ignition lockout) of the UDB board.

17. When 24 VAC is received at F1 of the ignition

module, it is then routed to the “TH” terminal of
the ignition module.

18. After 24 VAC is received at TH on the ignition

module, the contacts between pins F1 and F2 close
and send 24 VAC to pin J5-6 of the UGB board.

A signal must be received at this terminal to en­able output to the blower.

19. A 24 VAC signal is sent from J6-1 to the blower.

20. The blower is controlled by a PWM (pulse width

modulation) signal sent from J6-4 to start the
blower operating at 50% speed.

The combustion air blower will operate at 50% of
capacity for approximately ninety (90) seconds be­fore the modulating signal from the temperature
control will control the blower speed in relation­ship to the system water temperature.

21. Once sufficient air pressure is achieved in the

heater and the air pressure switch closes the NO
contacts, 24 VAC is sent to the heater interlock
connection.

If air pressure is insufficient or lost during heater
operation, a 24 VAC signal is sent from the NC
contacts of the air pressure switch to pin P4-10 of
the UDB board to indicate insufficient air pressure.

When the 24 VAC signal is sent to P4-10, the
same signal then energizes the coil of the time de­lay relay to remove a heat demand from the
temperature controller and restart the ignition se­quence after the five-second time delay.

23. After 15 seconds of combustion chamber pre-

purge, pin S1 sends 120 VAC to the Hot Surface
Igniter.

The Hot Surface Igniter will be energized for ap­proximately 30 seconds and must exceed 3.1 amp
draw during heat up.

24. During HSI heat-up, the UGB board is monitoring

current draw across pins J4-1 and J4-3.

25. Once the ignition module determines the proper

operation of the Hot Surface Igniter, a 24 VAC
signal is output from Valve pin on the ignition
module to energize the gas valve.

26. A 24 VAC signal is sent to the blue LED on the

front of the heater to signify “Burner Firing” and
to pin J5-2 on the UGB board to prove flame.

27. The gas valve is energized and the burner ignites.

28. The remote sensor is now trying to sense the flame.

If the flame is not rectified within 4 seconds, the
ignition module will shut down the gas valve and
lock out.

29. When burner flame is rectified, the gas valve will

remain at 50% fire for the remainder of the ninety
(90) seconds after CFH and then modulate in rela­tionship to the output signal to the combustion air
blower from the modulating temperature control.

30. When the CFH is satisfied, the heater will return to

a standby condition awaiting the next CFH.

Ignition Module

When additional heat is needed, the combustion air
blower starts to purge air from the combustion chamber
for 15 seconds. On proof-of-air flow, the air-proving
switch closes and the igniter is energized. To ensure
safe operation, the gas valve cannot open until the ig­niter is verified. The main burner is automatically lit
when the device is powered and pre-purged. The heater
performs its own safety check and opens the main
valve only after the igniter is proven to be capable of
ignition.

22. After receiving 24 VAC at the heater interlock,

power then travels to the P Switch terminal of the
ignition module.

The ignition module employs a 15 second pre­purge before the next sequence.

34

Fig. 29: Ignition Module

The standard single-try ignition module will lock out
after failing to light one time. To reset it, press and
release the small, recessed black push button located
inside of the cut-out on the lower right-hand corner of

the ignition module case. Turning off the power to
the heater WILL NOT reset the ignition module.

The optional ignition module will attempt to light three
times before locking out. To reset it, turn off power to
the heater, wait 30 seconds and re-apply power.

Code Condition

On System OK; No faults present

Off Possible control fault; Check power

SECTION C: Installation

The optional adjustable manual reset high limit is lo­cated inside the heater junction box. Push the reset
button and adjust the setting to approx. 40°F above
desired outlet temperature.

Fig. 30: Fixed Setting & Adjustable High Limit

(Manual Reset)

High Limit - Auto Reset (Optional)

The heater may be equipped with an optional adjust­able auto reset high limit temperature device.

The optional adjustable auto reset high limit is located
inside the heater junction box. Adjust the setting to
approx. 20°F above desired outlet temperature.

1 Flash Low air

2 Flashes

Flame in combustion chamber;

No call for heat

3 Flashes Ignition lockout

4 Flashes Low HSI current

5 Flashes Low 24 VAC

6 Flashes Internal fault; Replace control

Table O: Ignition Module

Diagnostic LED Flash Codes

High Limit - Manual Reset

The heater is equipped with a fixed setting manual re­set high limit temperature device as standard or it may
have an optional adjustable setting manual reset high
temperature device.

The fixed setting manual reset high limit is located on
the In/Out header of the heat exchanger on the right
side of the heater (accessible through the front door for
reset as necessary).

Fig. 31: Adjustable High Limit (Auto Reset)

Flow Switch

This standard, dual-purpose control, mounted and
wired in series with the main gas valve, shuts off heater
in case of pump failure or low water flow.

35

SECTION C: Installation

Fig. 32: Flow Switch

Modulating Temperature Control

High and Low Gas Pressure Switches
(Optional)

The optional low gas pressure switch connection
mounts upstream of the gas valve (on the inlet flange to
the gas valve) and is accessible through the removable
access panels on the rear of the heater to reset the gas
pressure switch, as necessary. It is used to ensure that
sufficient gas pressure is present for proper
valve/regulator performance. The low gas pressure
switch automatically shuts down the heater if gas sup­ply drops below the factory setting of 3.0 in. WC for
natural gas or LP gas.

The heater is equipped with a Raypak modulating tem­perature control. Refer to information starting on page
28 for information on the setting and use of this control.

Fig. 33: Modulating Temperature Control

Low Water Cut-Off (Optional)

The optional low water cut-off automatically shuts
down the burner whenever water level drops below the
level of the sensing probe. A 5-second time delay pre­vents premature lockout due to temporary conditions
such as power fluctuations or air pockets.

The optional high gas pressure switch connection
mounts down-stream of the gas valve. Special ports
are located on the backside of the gas valve and acces­sible from the front of the heater (to reset the gas
pressure switch) or through the removable access pan­els on the rear of the heater (to reset the gas pressure
switch), as necessary. If the gas pressure regulator in
the valve fails, the high gas pressure switch automati­cally shuts down the burner.

Operation of either the High or Low Gas Pressure
Switch will turn on an LED inside the switch housing.
Push the top of the plastic switch housing as shown in
Fig. 35 to reset a tripped pressure switch. The LED
will go out when the switch is reset.

Fig. 34: Low Water Cut-Off

Fig. 35: High/Low Gas Pressure Switch

Air Pressure Switch

The heater is equipped with an air pressure switch to
prove the operation of the blower before allowing the
ignition control to begin a Call for Heat. It is located
on the right side of the lower flange of the blower
mounting assembly, directly behind the junction box.

36

Fig. 36: Air Pressure Switch

Blocked Vent Switch

This heater is equipped with a blocked vent pressure
switch to prevent the operation of the heater when too
much of the vent is blocked. This switch is located on
the right side of the heater near the right rear corner.

SECTION C: Installation

Fig. 37: Blocked Vent Switch

UDB Diagnostic Board

This heater is equipped with a diagnostic board which
will indicate faults as they occur. It has the ability to
retain up to 256 faults in history. Refer to the Trouble­shooting section for instructions on accessing,
reviewing and clearing these faults.

SW1

SW2

Fig. 38: UDB Diagnostic Board

37

SECTION C: Installation

Wiring Diagrams

Models 503-1503

38

Models 1753-2003

SECTION C: Installation

39

SECTION C: Installation

40

SECTION D

Start-up

Pre Start-up

Filling System (Heating Boilers)

Fill system with water. Purge all air from the system.
Lower the system pressure. Open valves for normal
system operation, and fill system through feed pressure.
Manually open air vent on the compression tank until
water appears, then close vent.

Air Purge (Domestic Hot Water
Heaters)

Purge all air from system before lighting heater. This
can be normally accomplished by opening a down­stream valve.

Raypak offers an optional air vent for the MVB heaters
which can be screwed directly into the inlet side of the
header to ensure that air is purged from the system.
This option also includes an adapter to allow the air
vent to be piped (in the field) to a suitable drain as re­quired by the jurisdiction having authority.

Venting System Inspection

For Your Safety

WARNING: If you do not follow these instructions

exactly, a fire or explosion may result causing property
damage, personal injury or loss of life.

This appliance has a hot surface igniter. It is equipped
with an ignition device which automatically lights the
burners. Do not try to light the burners by hand.

BEFORE OPERATING, smell all around the appliance
area for gas. Be sure to smell near the floor because
some gas is heavier than air and will settle on the floor.

WHAT TO DO IF YOU SMELL GAS:

• Do not try to light any appliance.

• Do not touch any electrical switch; do not use any

telephone in your building.

• Immediately call your gas supplier from a

neighbor’s telephone. Follow the gas supplier’s in­structions.

• If you cannot reach your gas supplier, call the fire

department.

1. Check all vent pipe connections and flue pipe ma-

terial.

2. Make sure vent terminations are installed per code

and are clear of all debris or blockage.

• Use only your hand to push in or turn the gas con-

trol knob. Never use tools. If the knob will not turn
by hand, do not try to repair it, call a qualified ser­vice technician. Forced or attempted repair may
result in a fire or explosion.

• Do not use this appliance if any part has been under

water, immediately call a qualified service techni­cian to inspect the appliance and to replace any part

41

SECTION D: Start up

of the control system and any gas control which has
been under water.

• Check around unit for debris and remove combusti-

ble products, i.e. gasoline, etc.

Pre Start-up Check

1. Verify heater is filled with water.

2. Check system piping for leaks. If found, repair

immediately.

3. Vent air from system. Air in system can interfere

with water circulation. If the heater is equipped
with the optional air vent, ensure that it is adjusted
before firing the heater to make sure all air is
vented prior to start-up.

4. Purge air from gas line up to heater.

Initial Start-up

Tools Needed

• (1) 12-0-12, 24” scale U-tube manometer

• (2) 6-0-6, 12” scale U-tube manometer

• (1) Phillips screwdriver

• (1) Crescent wrench

• (1) Multi-meter

• (1) Amp probe

NOTICE: Digital manometers are not recommended.

Preparation

WARNING: Do not turn on gas at this time.

Attach Manometers to Measure Pressures

1. Turn off main gas valve.

2. Attach (1) 12” scale manometer to an upstream

bleedle valve on the gas supply pipe to the heater
(Measure point “A” in Fig. 39).

3. Attach (1) 24” scale manometer to the manifold

pressure tap located on the valve (Measure point
“C” in Fig. 39).

4. Attach (1) 12” scale manometer near the fan-

proving switch. Pull black cap from air pressure
switch tee and connect the manometer. NOTE: Re­tain caps for reinstallation later.

Fig. 39: Gas Pressure Measurement Location

Check Gas Supply Pressure

1. Slowly turn on main gas shut-off valve.

2. Read the gas supply pressure from the manometer;

minimum supply pressure for natural gas is 4.0 in.
WC, recommended supply is 7.0 in. WC, mini­mum supply pressure for propane gas is 4.0 in.
WC, recommended supply is 11.0” WC (dynamic
readings, full fire input).

Check Power Supply

With multi-meter at incoming power, check voltage
between:

Hot - Common (≈120 VAC)
Hot - Ground (≈120 VAC)
Common - Ground (< 1 VAC)

WARNING: If Common - Ground is > 1 VAC, STOP:

Contact electrician to correct ground failure. Failure to
do this may burn out 120V-24V transformer, or may
cause other safety control damage or failure.

3. If the pressure is > 14.0 in. WC, turn off the valve.

4. Check if the service regulator is installed and/or

adjust the service regulator.

Start-Up

Blower Adjustment

1. Turn off power.

2. Unplug cap at pressure switch and connect ma-

nometer to the tee.

3. Close manual firing valve.

4. Turn power on.

42

SECTION D: Start up

5. Check blower motor amp draw and the manometer

attached to fan pressure switch with the blower
running at 100% speed. The reading should be as
noted in Tables P and Q for both natural gas and
propane gas. If not, adjust the air shutter on the
blower to attain the correct values.

6. Measure the blower amp draw and compare the

measured values to the values in Table P. If the
measured value is different than the values in the
table (with the noted tolerance), contact the factory.

NOTE: Connect the amp probe to the 14 Ga.
black power wire going into the blower.

7. Turn power off.

8. Disconnect the manometer and reconnect the cap.

Model Amp Draw

503

753

1003

1.9

2.9

4.8

Setting

Tolerance

+0.0/-0.2

+0.0/-0.2

+0.0/-0.2

Manifold Adjustment

1. Turn off unit.

2. Open manual firing valves.

3. Turn on the unit, wait approximately 15 seconds,

and the igniter should glow (observable through
the observation port located at the front, bottom of
the heater). Look into sight glass located at the
bottom of the front panel to check igniter operation.
Gas valve should open in 45-60 seconds.

4. If burner does not light on first trial. It will go into

lockout with the standard ignition module. If it is
equipped with the optional 3-try ignition module,
it will try for ignition up to three times.

5. Main burner ignition: Check manifold gas pressure

at gas valve outlet pressure tap (connection “C” in
Fig. 39). This should read per the values in Table
R for natural gas and propane gas.

6. If the pressure reading differs by more than ± 0.2

in. WC, STOP – Call the factory for directions on
what to do next!

1253

1503

1753

2003

Table P: MVB Blower Amp Draw

Model

6.3

8.1

13.5

14.8

+0.0/-0.2

+0.0/-0.2

+0.0/-0.5

+0.0/-0.5

Air Pressure Setting*

(in. WC)

503 -2.3

753 -2.9

1003 -3.0

1253 -3.5

1503 -4.0

1753 -4.6

2003 -4.1

* Settings +/- 0.2” WC

Table Q: MVB Air Pressure Requirements

CAUTION: Special manifold and air settings may be

required.

Manifold Gas Pressure Setting*

Model

High Fire Values (in. WC)

Natural Gas LP Gas

503 -0.1 -0.1

753 -0.1 -0.1

1003 -0.2 -0.2

1253 -0.1 -0.1

1503 -0.4 -0.3

1753 0.4 0.4

2003 0.6 0.6

* Settings +/- 0.2” WC

Table R: MVB Manifold Gas Pressure Settings

43

SECTION D: Start up

Safety Inspection

1. Check all thermostats and high limit settings.

2. During the following safety checks leave manome-

ters hooked up, check and record.

3. If other gas-fired appliances in the room are on the

same gas main, check all pressures on the MVB
with all other equipment running.

4. Check thermostats for ON-OFF operation.

5. Check high limits for ON-OFF operation.

6. While in operation, check flow switch operation

7. Check the low gas pressure switch (if provided).

(For proper adjustment, use the attached manome­ters, if available, to set pressure. The scales on the
switch are approximate only.) Low gas pressure
switch (if provided) must be set at 3.0 in. WC for
natural gas and propane gas.

8. Make sure that the high gas pressure switch (op-

tional) is set to 3.0 in. WC for both natural gas and
propane gas.

Follow-Up

Safety checks must be recorded as performed.

Turn heater on. After main burner ignition:

1. Check manometer for proper readings.

2. Cycle heater several times and re-check readings.

3. Remove all manometers and replace caps and

screws.

4. Check for gas leaks one more time.

Leak Test Procedure: Dual-Seat Gas
Valve

Proper leak testing requires three pressure test points in
the gas train.

Remove the access panel on the rear of the heater to
access the gas valve for this test. Test point A is a

bleedle valve located upstream of the combination gas
valve on the supply manifold.

Test point B is a bleedle valve located between the two
automatic gas valve seats.

Test point C is a bleedle valve located downstream of
both automatic gas valve seats and upstream of the
manual valve. Refer to Fig. 40.

These tests are to be conducted with the electrical
power to the heater turned OFF.

1. Manually close the downstream leak test valve.

2. Open the bleedle valve at test point A and connect

a manometer to it. Verify that there is gas pressure
and that it is within the proper range (NOTE: must
not exceed 14.0 in. WC).

3. Open test point B and connect a rubber tube to it.

Connect the other end of the tube to a manometer
and look for a build-up of pressure. Increasing
pressure indicates a leaking gas valve which must
be replaced.

4. Next, close the upstream manual gas valve (field

supplied) and remove the manometers from the
bleedle valves in test point A and test point B.
Connect a rubber tube from the test point A
bleedle valve to the test point B bleedle valve and
open the upstream manual gas valve. Make sure
that test point A & B bleedle valves have been
opened so as to allow gas to flow. This will bring
gas pressure to the second valve seat.

5. Open the bleedle valve at test point C and connect

a second rubber tube to it. Connect the other end
of the tube to a manometer and look for a build-up
of pressure. Increasing pressure indicates a leaking
gas valve which must be replaced.

6. Remove rubber tube and manometers. Close each

test point bleedle valve as the tubes are removed.

7. After no leakage has been verified at all valve

seats and test valves, open downstream leak test
valve and restore electrical power to the heater.

44

SECTION D: Start up

8. Test limit control: While burner is operating, move

indicator on high limit control below actual water
temperature. Burner should go off while blower
and circulator continue to operate. Raise setting on
limit control above water temperature and burner
should re-ignite after pre-purge time delay.

NOTE: Ignition control may have to be reset after
this portion of the test.

9. Test ignition system safety device:
a. Open manual gas valve. Turn power on.
b. Set thermostat to call for heat.
c. When the heater is in operation, pull cap off of

tee in air switch hose. The burner should go
off almost immediately.

d. Reattach cap on tee. Burner should re-ignite

after pre-purge time delay. NOTE: Ignition
control may have to be reset after this portion
of the test.

Fig. 40: Leak Test Procedure

Post Start-Up Check

Check off steps as completed:

1. Verify that the heater and heat distribution units or

storage tank are filled with water.

2. Confirm that the automatic air vent (if used) was

opened two full turns during the venting procedure.

3. Verify that air has been purged from the system.

4. Verify that air has been purged from the gas piping,

and that the piping has been checked for leaks.

5. Confirm that the proper start-up procedures were

followed.

6. Inspect burner to verify flame.

7. Test safety controls: If heater is equipped with a

low water cut-off or additional safety controls, test
for operation as outlined by manufacturer. Burner
should be operating and should go off when con­trols are tested. When safety devices are restored,
burners should re-ignite after pre-purge time delay.

10. To restart system, follow lighting instructions in

Section E.

11. Check to see that the high limit control is set above

the design temperature requirements of the system.

For multiple zones: Check to make sure the flow is
adjusted as required in each zone.

12. Check that the heater is cycled with the thermostat.

Raise the setting on the thermostat to the highest
setting and verify that the heater goes through the
normal start-up cycle. Reduce to the lowest setting
and verify that the heater goes off.

13. Observe several operating cycles for proper opera-

tion.

14. Set the heater thermostat to desired temperature.

15. Review all instructions shipped with this heater

with owner or maintenance person, return to enve­lope and give to owner or place the instructions
inside front panel on heater.

45

SECTION D: Start up

46

SECTION D: Start up

SECTION E

Operation

Lighting Instructions

1. Before lighting, make sure you have read all of the

safety information in this manual.

2. Remove upper front panel.

3. Set the thermostat to the lowest setting.

4. Turn off all electrical power to the appliance.

5. This appliance is equipped with an ignition device

which automatically lights the burner. Do not try
to light the burner by hand.

6. Turn on main manual gas valve field installed near

gas inlet connection on back of heater.

7. Wait 5 minutes to clear out any gas. Then smell

for gas, especially near the floor. If you then smell
gas, STOP! Follow the steps in the safety informa­tion on the front cover of this manual. If you do
not smell gas, go to next step.

8. Turn on all electrical power to the appliance.

9. Set thermostat to desired setting. The appliance

will operate. The igniter will glow after the pre­purge time delay (15 seconds). After igniter
reaches temperature (30 seconds) the main valve
should open. System will try for ignition one time
(three times on optional 3-try ignition module). If
flame is not sensed, lockout will commence.

12. If heater fails to start, verify the following:
a. There are no loose connections or that the ser-

vice switch is off.

b. High temperature limit switch is set above wa-

ter temperature or manual reset high limit is
not tripped.

c. Thermostat is set above water temperature.
d. Gas is on at the meter and the heater.
e. Incoming dynamic gas pressure to the gas

valve is NOT less than 4.0 in. WC for natural
gas or propane gas.

To Turn Off Gas To Appliance

1. Shut off manual gas valve field installed near gas

inlet connection on back of heater.

2. Remove upper front panel.

3. Set the thermostat to lowest setting.

4. Turn off all electrical power to the appliance if

service is to be performed.

5. Replace access panel.

10. If the appliance will not operate, follow the in-

structions “To Turn Off Gas To Appliance,” and
call your service technician or gas supplier.

11. Replace upper front panel.

47

SECTION E: Operation

48

SECTION D: Start up

p

p

g

p

y

SECTION F

Troubleshooting

Step 1

Step 2

Step 3

Step 4

Step 5

Step 6

Step 7

Does the power switch provide

power to the control panel?

YES

YES

Is Disable connection intact?

YES

Does the combustion air

blower come on?

Is 4-20mA present at the quick

disconnects on the black and blue

wires of the tem

YES

Is 24VAC at the NC side of

the air pressure switch?

YES

Is 24VAC at PS on ignition module?

Is connecting plug secure?

YES

Does igniter prove?

YES

Is the flame sensor signal to the

i

nition module greater than 1 uA DC?

YES

Is there a Call For

erature controller?

Does F2 on ignition module

have AC

NO

NO

Heat?

NO

NO

YES

ower?

NO

Is Amp draw during heat-

YES

NO

Check the switch and/or

line voltage

NO

Reattach.

Is there 120VAC at the blower or

blower relay?

YES

NO

NO

Is blower pressure setting

(vacuum) correct?

NO

up for HSI greater than

3.1 Amps?

Is air switch bouncing?

Is gas pressure correct?

YES

Unit is in standby mode.

Is diagnostic board

indicating open

Is there continuity in the wire

between F2 and Pin J5-6?

Correct wiring.

YES

NO

Check and correct power

NO

YES

Replace air pressure switch.

connections at main terminal
block, circuit breaker panel or

NO

NO

Replace HSI

NO

YES

blower relay.

Replace temperature

controller.

Correct Safet

NO

Correct the shutter

setting or blower

amp draw.

NO

Repair or

Re

lace wire.

Step 8

Step 9

Is the unit running?

YES

The unit is okay

Is static and dynamic inlet gas

pressure correct?

NO

Call our Technical Service Department

1-800-927-2975 Outside California

1-800-627-2975 Inside California

YES

49

NO

Replace gas valve

Correct the gas pressure.

SECTION F: Troubleshooting

UDB Fault History

To view the fault codes in the UDB history file:

1. Press and hold the switch labeled “SW1” for 5

seconds to access the fault history. LED 17 will
begin to flash when the history has been accessed.
See Fig. 38 on page 37.

2. Press the switch labeled “SW2” to scroll through

the recorded faults in history.

3. When a fault is being displayed, the corresponding

LED will light AND LED 17 will flash at a rate
that corresponds to the fault number.

4. The faults are recorded and displayed on a last in,

first out basis. The last fault recorded will be the
first fault displayed. There is no time or date stamp
associated with these faults.

5. Continue to push “SW2” to view subsequent faults.

6. When the history of faults has been exhausted,

pushing “SW2” again will roll the fault history
over and it will start again.

7. To exit the fault history, press and hold “SW1” for

5 seconds, or wait for 4 minutes and the board will
automatically exit the history mode (fault LEDs
will go out).

To clear the fault history, press and hold both “SW1”
and “SW2” for 5 seconds.

NOTE: Once the history has been cleared, it cannot be
recovered.

50

SECTION G

Maintenance

Suggested Minimum
Maintenance Schedule

Regular service by a qualified service agency and mainte­nance must be performed to ensure maximum operating
efficiency.

Maintenance as outlined below may be performed by the
owner.

Daily

1. Check that the area where the heater is installed is free

from combustible materials, gasoline, and other flam­mable vapors and liquids.

2. Check for and remove any obstruction to the flow of

combustion or ventilation air to heater.

Monthly

1. Check for piping leaks around pumps, mixing valves,

relief valves, and other fittings. If found, repair at once.
DO NOT use petroleum-based stop-leak compounds.

2. Visually inspect burner flame.

3. Visually inspect venting system for proper function,

deterioration or leakage.

4. Visually inspect for proper operation of the condensate

drain in the venting. If leaks are observed repair at
once.

5. Check air vents for leakage.

Yearly (Beginning Of Each Heating
Season)

Schedule annual service call by qualified service agency.

1. Visually check top of vent for soot. Call service person

to clean. Some sediment at bottom of vent is normal.

2. Visually inspect venting system for proper function,

deterioration or leakage. Ensure that condensate drain
is inspected and ensure that condensate is being di­rected to appropriate condensate management system
or drain, as required by local codes.

3. Check that area is free from combustible materials,

gasoline, and other flammable vapors and liquids.

4. Check for and remove any obstruction to the flow of

combustion or ventilation air to heater.

5. Follow pre-start-up check in Section D.

6. Visually inspect burner flame. It should be light blue

at full input. Remove and visually inspect hot surface
igniter and sensor for damage, cracking or debris
build-up.

7. Check operation of safety devices. Refer to manufac-

turers’ instructions.

8. Follow oil-lubricating instructions on pump (if re-

quired). Over-oiling will damage pump.
Water-lubricated circulators do not need oiling.

9. To avoid potential of severe burn, DO NOT REST

HANDS ON OR GRASP PIPES. Use a light touch;
return piping will heat up quickly.

10. Check blower and blower motor.

51

SECTION G: Maintenance

11. Check for piping leaks around pumps, relief valves

and other fittings. Repair, if found. DO NOT use pe­troleum-based stop-leak.

Periodically

1. Check relief valve. Refer to manufacturer’s instruc-

tions on valve.

2. Test low water cut-off (if equipped). Refer to manu-

facturer’s instructions.

Preventive Maintenance
Schedule

The following is required procedure in all jurisdictions
which require CSD-1 and good practice for all MVB instal­lations.

Daily

1. Check gauges, monitors and indicators.

2. Check instrument and equipment settings. (See “Post

Start-Up Check” on page 45.)

3. Check burner flame. (Should see light blue flame at

full input rate).

Weekly

For low-pressure heaters, test low-water cut-off device.
(With heater in pre-purge, depress the low water cut-off
test button. Appliance should shut-off and ignition fault
light should come on. Depress reset button on front of
heater control panel to reset).

1. Check igniter. (Resistance reading should be 42-70

ohms at ambient temperature.)

2. Check flame signal strength. (Flame signal should be

greater than 1 microamp as measured at the 2 pins on
the upper left corner of the ignition control).

3. Check flame failure detection system. (See “Post Start-

Up Check” on page 45.)

4. Check firing rate control by checking the manifold

pressure. (See “Manifold Adjustment” on page 43.)

5. Make auditory and visual check of main fuel valve.

Monthly

1. Check flue, vent, stack, or outlet dampers.

2. Test blower air pressure. (See “Blower Adjustment”

on page 42.)

3. Test high and low gas pressure interlocks (if equipped).

(See “Safety Inspection” on page 44.)

Semi-Annually

1. Recalibrate all indicating and recording gauges.

2. Check flame failure detection system components.

3. Check firing rate control by checking the manifold

pressure. (See “Manifold Adjustment” on page 43.)

4. Check piping and wiring of all interlocks and shut-off

valves.

Annually

1. Test flame failure detection system and pilot turndown.

2. Test high limit and operating temperature. (See “Post

Start-Up Check,” page 45.)

3. Check flame sensors.

4. Conduct a combustion test at full fire. Carbon dioxide

should be 8.0 to 9.0% at full fire for natural gas, and
between 9.0 to 10.0% for propane gas. Carbon monox­ide should be < 100 ppm.

5. Check valve coil for 60 cycle hum or buzz. Check for

leaks at all valve fittings using a soapy water solution
(while heater is operating). Test other operating parts
of all safety shut-off and control valves and increase or
decrease settings (depending on the type of control)
until the safety circuit opens. Reset to original setting
after each device is tested.

6. Perform leakage test on gas valves. (See Fig. 40.)

7. Test air switch in accordance with manufacturer’s

instructions. (Turn panel switch to the “On” position
until blower is proven, then turn the switch to “Off.”

8. Inspect burner.

As Required

1. Recondition or replace low water cut-off device (if

equipped).

2. Check drip leg and gas strainers.

3. Perform flame failure detection tests.

4. Test safety/safety relief valves in accordance with

ASME Heater and Pressure Vessel Code Section IV.

52

SECTION H

Appendix

Inside Air Contamination

All heaters experience some condensation during start­up. The condensate from flue gas is acidic. Combustion
air can be contaminated by certain vapors in the air
which raise the acidity of the condensate. Higher acid­ity levels attack many materials including stainless
steel, which is commonly used in high efficiency sys­tems. The heater can be supplied with corrosion­resistant, non-metallic intake air vent material. You
may, however, choose to use outside combustion air
for one or more of these reasons:

1. Installation is in an area containing contaminants

listed below which will induce acidic condensation.

2. You want to reduce infiltration into your building

through openings around windows and doors.

3. You are using AL29-4C stainless steel vent pipe,

which is more corrosion-resistant than standard
metallic vent pipe. In extremely contaminated ar­eas, this may also experience deterioration.

Products causing contaminated combustion air:

• spray cans containing chloro/fluorocarbons

• permanent wave solutions

• chlorinated waxes/cleaners

• chlorine-based swimming pool chemicals

• calcium chloride used for thawing

• sodium chloride used for water softening

• refrigerant leaks

• paint or varnish removers

• hydrochloric acid/muriatic acid

• cements and glues

• antistatic fabric softeners used in clothes dryers

• chloride-type bleaches, detergents, and cleaning

solvents found in household laundry rooms

• adhesives used to fasten building products

• similar products.

Areas where contaminated combustion air commonly
exists:

• dry cleaning/laundry areas

• metal fabrication plants

• beauty shops

• refrigeration repair shops

• photo processing plants

• auto body shops

• plastic manufacturing plants

• furniture refinishing areas and establishments

new building construction

•

• remodeling areas

• open pit skimmers.

Check for areas and products listed above before in­stalling heater. If found:

• remove products permanently, OR

• install TruSeal direct vent.

53

LIMITED PARTS WARRANTY

MVB – TYPES H AND WH

MODELS 503-2003

SCOPE

Raypak, Inc. (“Raypak”) warrants to the original owner that all parts of this heater which are actually manufactured by Raypak will be free
from failure under normal use and service for the specified warranty periods and subject to the conditions set forth in this Warranty. Labor
charges and other costs for parts removal or reinstallation, shipping and transportation are not covered by this Warranty but are the
owner’s responsibility.

HEAT EXCHANGER WARRA NTY

Domestic Hot Water
Five (5) years from date of heater installation. Includes copper heat exchanger with bronze waterways.
Ten (10) years from date of heater installation. Includes only cupro-nickel heat exchanger with bronze waterways.
Space Heating (Closed Loop System)
Ten (10) years from date of heater installation. Includes both cupro-nickel and copper heat exchanger with bronze water-ways.
Thermal Shock Warranty
Twenty (20) years from date of heater installation against “Thermal Shock” (excluded, however, if caused by heater operation at large
changes exceeding 150°F between the water temperature at intake and heater temperature, or operating at heater temperatures exceed­ing 230°F).

ANY OTHER PART MANUFA CTURED BY RAYPAK

One (1) year warranty from date of heater installation, or eighteen (18) months from date of factory shipment based on Raypak’s records,
whichever comes first.

SATISFACTORY PROOF OF INSTALLATION DATE, SUCH AS INSTALLER INVOICE, IS REQUIRED. THIS WARRANTY WILL BE
VOID IF THE HEATER RATING PLATE IS ALTERED OR REMOVED.

ADDITIONAL WARRANTY EXCLUSIONS

This warranty does not cover failures or malfunctions resulting from:

1. Failure to properly install, operate or maintain the heater in accordance with our printed instructions provided;

2. Abuse, alteration, accident, fire, flood and the like;

3. Sediment or lime build-up, freezing, or other conditions causing inadequate water circulation;

4. High velocity flow exceeding heater design rates;

5. Failure of connected systems devices, such as pump or controller;

6. Use of non-factory authorized accessories or other components in conjunction with the heater system;

7. Failing to eliminate air from, or replenish water in, the connected water system;

8. Chemical contamination of combustion air or use of chemical additives to water.

PARTS REPLACEMENT

Under this Warranty, Raypak will furnish a replacement for any failed part. The failed part must first be returned to Raypak if requested,
with transportation charges prepaid, and all applicable warranty conditions found satisfied. The replacement part will be warranted for
only the unexpired portion of the original warranty. Raypak makes no warranty whatsoever on parts not manufactured by it, but Raypak
will apply any such warranty as may be provided to it by the parts manufacturer.

TO MAKE WARRANTY CLA IM

Promptly notify the original installer, supplying the model and serial numbers of the unit, date of installation and description of the prob­lem. The installer must then notify his Raypak distributor for instructions regarding the claim. If either is not available, contact Service
Manager, Raypak, Inc., 2151 Eastman Avenue, Oxnard, CA 93030 or call [phone]. In all cases proper authorization must first be
received from Raypak before replacement of any part.

EXCLUSIVE WARRANTY - LIMITATION OF LIABILITY

This is the only warranty given by Raypak. No one is authorized to make any other warranties on Raypak’s behalf. THIS WARRANTY IN
LIEU OF ALL OTHER WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO IMPLIED WARRANTIES OF MER­CHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. RAYPAK’S SOLE LIABILITY AND THE SOLE REMEDY AGAINST
RAYPAK WITH RESPECT TO DEFECTIVE PARTS SHALL BE AS PROVIDED IN THIS WARRANTY. IT IS AGREED THAT RAYPAK
SHALL HAVE NO LIABILITY, WHETHER UNDER THIS WARRANTY, OR IN CONTRACT, TORT, NEGLIGENCE OR OTHERWISE,
FOR ANY SPECIAL, CONSEQUENTIAL, OR INCIDENTAL DAMAGE, INCLUDING DAMAGE FROM WATER LEAKAGE. Some states
do not allow limitations on how long an implied warranty lasts, or for the exclusion of incidental or consequential damages. So the above
limitation or exclusion may not apply to you.

This Limited Warranty gives you specific legal rights. You may also have other rights which may vary from state to state. We suggest that
you complete the information below and retain this certificate in the event warranty service is needed. Reasonable proof of the effective
date of the warranty (date of installation) must be presented, otherwise, the effective date will be based on the rate of manufacture plus
thirty (30) days.

Original Owner Model Number
Mailing Address Serial Number
Date of Installation
City State Zip Code Installation Site
Daytime Telephone Number Contractor/Installer

RAYPAK, INC y 2151 Eastman Avenue y Oxnard, CA 93030-9786 y [phone] y Fax [phone] y www.raypak.com

NOTES:

_____________________________________________________________________________________________

_____________________________________________________________________________________________

_____________________________________________________________________________________________

_____________________________________________________________________________________________

_____________________________________________________________________________________________

_____________________________________________________________________________________________

_____________________________________________________________________________________________

_____________________________________________________________________________________________

_____________________________________________________________________________________________

_____________________________________________________________________________________________

_____________________________________________________________________________________________

_____________________________________________________________________________________________

_____________________________________________________________________________________________

_____________________________________________________________________________________________

_____________________________________________________________________________________________

_____________________________________________________________________________________________

_____________________________________________________________________________________________

_____________________________________________________________________________________________

_____________________________________________________________________________________________

_____________________________________________________________________________________________

_____________________________________________________________________________________________

_____________________________________________________________________________________________

_____________________________________________________________________________________________

_____________________________________________________________________________________________

_____________________________________________________________________________________________

www.raypak.com

Raypak, Inc., 2151 Eastman Avenue, Oxnard, CA 93030 [phone] Fax [phone]

Raypak Canada Limited, 2805 Slough St., Mississauga, Ontario, Canada L4T 1G2 [phone] Fax [phone]