LAARS Mighty Therm HH Installation Manual
Installation and Operation Instructions Document 1065D
Installation and Operation
Instructions for
Mighty Therm
Model HH
Sizes 2000-5000
Hydronic Boilers
FOR YOUR SAFETY: This product must be installed and serviced by a professional service technician,
qualified in hot water heater installation and maintenance. Improper installation and/or operation could
create carbon monoxide gas in flue gases which could cause serious injury, property damage, or death.
Improper installation and/or operation will void the warranty.
WARNING
If the information in this manual is not followed exactly, a fire or explosion may result
causing property damage, personal injury or loss of life.
Do not store or use gasoline or other flammable vapors and liquids in the vicinity of this or
any other appliance.
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 nearby phone. Follow the gas supplier's
instructions.
• If you cannot reach your gas supplier, call the fire department.
Installation and service must be performed by a qualified installer, service agency, or gas
supplier.
H0147600D
A subsidiary of BRADFORD WHITE Corporation
Page 2
LAARS Heating Systems
TABLE OF CONTENTS
SECTION 1.
General Information
1A. Introduction...................................................3
1B. Flow Requirements ......................................4
1C. Variable Water Flow Systems ......................4
1C-1. A Special Note About 3-Way
Water Valves ................................................ 5
1C-2. System Pressure Requirements................... 5
1D. Warning Regarding Chilled
Water Systems ............................................. 5
SECTION 2.
Installation
2A. Boiler Placement .......................................... 5
2B. Installation of Indoor Boilers .........................6
2B-1. Combustion Air Supply ................................. 6
2B-2. Venting ......................................................... 7
2C. Installation of Outdoor Heater....................... 7
2D. Freeze Protection.........................................8
2E. Gas Supply and Piping.................................8
2F. Electrical Wiring............................................9
2G. Piping of System to Boiler ............................9
2H. Filling Fully-Connected System ..................10
3C. To Turn Off Boiler ....................................... 12
3D. To Shut Down System ................................ 12
SECTION 4.
Maintenance
...................................................................12
SECTION 5.
Troubleshooting and Analysis of
Service Problems
...................................................................13
SECTION 6.
Conversion of VW from Indoor
to Outdoor Models
...................................................................15
SECTION 7.
Parts Description and Order Numbers
...................................................................18
SECTION 3.
Operation
3A. Initial Start Up.............................................10
3B. To Start Up System ....................................11
Mighty Therm Hydronic Boiler
Page 3
SECTION 1.
General Information
IMPORTANT WARNING:
The Model HH hydronic boiler must be installed in
accordance with the procedures outlined in this
manual. Warranty does not apply to boilers not
installed or operated in accordance with these
procedures. Consult local building and safety codes
before proceeding with work. The installation must
conform to the requirements of the authority having
jurisdiction or, in the absence of such requirements,
to the latest edition of the National Fuel Gas Code,
ANSI Z223.1 and/or in Canada, CAN1-B149
requirement.
When required by the authority having
jurisdiction, the installation must conform to
American Society of Mechanical Engineers safety
code for controls and safety devices for automatically
fired boilers No. CSD-1, and in Canada, CGA3.3.
Any modification to the boiler, its gas controls, gas
orifices, wiring or draft diverter may void the Laars
warranty. If field conditions require such
modifications, consult Factory.
1A. Introduction
This manual provides information for the
installation and operation of Laars boilers. It is
strongly recommended that all application and
installation procedures be reviewed completely before
proceeding with the installation. Consult the factory,
or local factory representative, with any problems or
questions regarding this equipment. Experience has
shown that most operating problems are caused by
improper installation.
Model HH boilers are offered in two
configurations: An indoor version and an outdoor
version. The indoor version is convertible for outdoor
use with the installation of a conversion kit as
described in Section 6 of this manual. The two
configurations are shown in Figure 1.
Some accessory items are shipped in separate
packages. Verify receipt of all packages listed on the
packing slip. Inspect everything for damage
immediately upon delivery, and advise the carrier of
any shortages or damage. Any such claims should be
filed with the carrier. The carrier, not the shipper, is
responsible for shortages and damage to the shipment
whether visible or concealed.
Indoor Outdoor
When boiler is ordered with stage or modulated control and sales order states it is to be used on a variable flow system, the
temperature controller is factory installed in the outlet water.
Figure 1. Boiler Configuration.
Page 4
Fan Coils
p
1B. Flow Requirements
All low volume hydronic boilers must have
continuous flow through the heat exchanger when
firing, for proper operation. The system pump must be
capable of developing sufficient pressure to overcome
the resistance of the boiler plus the entire circulating
system at the designated GPM (see Table 1). The
temperature rise across the boiler should never exceed
40° F.
NOTE: Water entering boiler should be 105°F
minimum.
1C. Variable Water Flow Systems
Heating systems using zone valves, zone pumps
or 3-way valves can experience reduced water flow
through the boiler. This can result in an excessive
water temperature rise and unstable boiler operation. If
system water flow is variable, it must not be allowed
to fall below 30% of full flow. The boiler must be
equipped with staged or modulated fire with the
temperature sensor installed in the outlet water. State
variable flow when ordering. Laars recommends
primary-secondary pumping for all variable flow
systems. Primary-secondary pumping is mandatory for
variable flow systems where minimum flows are less
than 30% of full flow conditions. The boiler pump in a
primary-secondary system maintains constant flow
through the boiler even though the system flow is
variable. In a primary-secondary system the pressure
drop of the boiler is not added to the system (see
Figure 2).
LAARS Heating Systems
Convectors Baseboards
or Fan Coils
Zone Valves
Compression Tank
Pump
(Location varies
with model)
Figure 2. Primary-Secondary System.
12"
Max.
Unit
System Pum
20°F 25°F 30°F 35°F
Size (I) Size (E) GPM H/L GPM H/L GPM H/L GPM H/L
20001P ------ 164 3.91 131 3.6 109 1.8 94 0.7
2P ------ 164 10.5 131 7.4 109 4.9 94 3.0
24501P 22001P 201 5.9 161 3.9 134 3.8 115 2.3
2P 2P 201 16.4 161 10.2 134 7.7 115 5.7
30501P 28001P 250 9.3 200 5.9 167 4.5 143 3.8
2P 2P * * 200 16.4 167 12.5 143 8.5
35001P 32001P 284 12.0 230 8.7 189 5.7 164 3.9
2P 1P * * * * 189 16.8 164 10.5
40501P 36001P 332 17.2 266 11.9 222 8.1 190 5.8
2P2P****22224.0 190 16.0
45001P 40001P 369 21.75 295 13.2 246 10.0 211 7.0
2P 2P * * * * * * 211 20.0
50001P 45001P 410 27.0 328 16.8 273 13.0 234 9.0
2P2P*** *****
HIGH NORMAL LOW
* Not recommended, consult factory.
I=Indoor, E=Outdoor. GPM=Water flow. H/H=Pressure drop (head loss)through the boiler, expressed in Ft. of H
2P=Two-pass heat exchanger. Shaded area is the recommended flow and temperature rise.
0. 1P=Single-pass heat exchanger.
2
Table 1. Water Flow, Temperature Rise and Pressure Drop.
Mighty Therm Hydronic Boiler
Page 5
1C-1. A Special Note About 3-Way
Water Valves
3-way water valves (2 position or proportional)
are sometimes used to divert water around a boiler and
control the temperature of water being supplied to the
system. Valves installed in this manner must be
supplied with an end switch or some other suitable
control to shut off the boiler when the flow is reduced
to 30%. The boiler must be supplied with staged or
modulated fire as indicated in Section 1C, Variable
Water Flow Systems.
It is often possible to accomplish excellent water
temperature control without 3-way valves through
proper application of staged or modulated firing
systems. Consult the factory or local Laars
representative for assistance with such systems.
1C-2. System Pressure Requirements
The Model HH boilers are designed to operate
on closed, pressurized systems. A minimum of 12 psi
should be maintained on the system where boiler
supply water temperatures are 200°F or less. If higher
temperatures are required, the minimum system
pressure should be at least 15 psi above the water
vapor pressure corresponding to the elevated water
temperature.
The Model HH boilers are not suitable for
open systems unless the supply water temperatures are
kept below 180°F, and a minimum of 5 psi static head
is maintained at the boiler.
1D. Warning Regarding Chilled
Water Systems
When a boiler is connected to an air conditioning
system where the same water is used for heating and
cooling, chilled water must be prevented from entering
the boiler. When changing such a system from cooling
to heating, the chilled water should be allowed to
circulate through the building after the chiller has been
turned off long enough for the water to warm up to at
least 70°F before the water is allowed to flow into the
boiler. It is equally important to prevent hot water
from entering the chiller. The system shown in Figure
3 is suggested to make sure that the system water is
neither too hot nor too cold when a changeover from
heating to cooling, or vice versa, takes place. When a
boiler is connected to heating coils located in air
handling units (where they may be exposed to
refrigerated air circulation), the boiler piping system
shall be equipped with a flow control valve or other
automatic means to prevent gravity circulation of
chilled water through the boiler. Chilled water in the
boiler will create condensate on the boiler tubes which
will drip on the burners and may extinguish the pilot.
Boilers installed in violation of either of the
above requirements may void the warranty.
SECTION 2.
Installation
Changeover from Heating to Cooling
DPDT Manual or Automatic
Change-over Switch
DPDT - Set at Change-over
Temperature
From
Chiller
3-Way Valve No. 1
Change-over
(Heating and Cooling)
Suggested Wiring Diagram For
Tempering System Water at
Clock Timer
Auto-resetting
Set at 15 minute SPDT
115/24V
Transformer
Valve Motors
2-Pos
3-Wire - 24V
From
Boiler
3-Way Valve No. 2
To By-pass
Both Heater and
Chiller
By-pass
To Boiler
and
Chiller
From
System
To
System
2A. Boiler Placement
The boiler must be placed to provide clearances
on all sides for maintenance and inspection. There
must also be minimum distances maintained from
combustible surfaces.
All boilers must be installed on a noncombustible floor. Under no circumstances can boilers
be installed on carpeting.
The National Fuel Code allows a boiler to be
placed on a combustible surface when such an
installation complies with the local codes. This code
specifies the surface under the boiler be protected with
hollow masonry no less than 4" thick, covered with
sheet metal at least 20 Ga. in thickness. Such masonry
Clearance Indoor Outdoor
From (Inches) (Inches)
Top 24 —
Water Connection Side 24 24
Opposite Side 24 24
Front 48 48
Rear 24 24
Vent 6 —
Figure 3. Boiler-Chiller Installation. Table 2. Minimum Clearances from Combusible Surfaces.
Page 6
0
LAARS Heating Systems
must be laid with ends unsealed, and joints matched
in such a way as to provide a free circulation of air
from side to side through the masonry (see Figure 4).
2B. Installation of Indoor Boilers
2B-1. Combustion Air Supply
1. The boiler location must provide sufficient air
supply for proper combustion, and ventilation
of the surrounding area as outlined in the latest
edition of ANSI standard Z223.1, and/or in
Canada CAN1-B149 requirement, and any local
codes that may be applicable. Inadequate
combustion air supply may result in incomplete
combustion and consequent sooting of the heat
exchanger and unsafe operation of the boiler.
2. In general, in the U.S., these requirements
specify that boiler rooms, which represent
confined spaces, should be provided with two
permanent air supply openings communicating
directly through the wall to outside air; one
within 12 inches of the ceiling, the other within
12 inches of the floor. Each opening should
have a minimum free area of one square inch
per 4,000 BTUs/H input rating of all appliances
in the enclosed area. See Table 3 for
recommended air supply for each model. An
improperly ventilated equipment room can get
excessively hot and cause accelerated
deterioration of controls and electrical
components.
NOTE: In Canada (Table 3 does not apply)
consult local building and safety codes or, in the
absence of such requirements, follow CGA
requirement, and/or CAN1-B149 standard.
3. Exhaust Fans or Vents: Any equipment which
exhausts air from the boiler room can deplete the
combustion air supply or reverse the natural draft
action of the venting system. This could cause
flue products to accumulate in the boiler room.
Additional air must be supplied to compensate
for such exhaust. The information in Table 3 is
not applicable in installations where exhaust fans
or blowers of any type are used. Such
installations must be designed by qualified
engineers.
4. If a blower or fan is used to supply air to the
boiler room, the installer should make sure it
does not create drafts which could cause
nuisance shutdowns of the pilot. If a blower is
necessary to provide adequate combustion air to
the boiler, a suitable switch or equivalent must
be wired into the boiler control circuit to prevent
the boiler from firing unless the blower is
operating.
5. The boiler must be completely isolated and
protected from any source of corrosive chemical
fumes such as emitted by trichlorethylene,
perchlorethylene, chlorine, etc.
Base Must Extend Out
Min. 12" On All Sides
Of Heater Frame
Concrete Blocks Or Tile
Min. 7" High With 3" Min.
Air Openings
Blocks must provide solid base and be braced so
they cannot slip out of place. Air openings in blocks
must be arranged to provide unobstructed opening
through entire width or length of base.
Figure 4. Non-combustible Base.
Metal Plate 2
Ga. Min.
Under Entire
Heater
Indoor Each Opening*
Size (Square Inches)
2000 500
2450 613
3050 763
3500 875
4050 1013
4500 1125
5000 1250
Net Free Area in Square Inches*
*Area indicated is for one of two openings;
one at floor level and one at the ceiling, so
the total net free area would be double the
figures indicated. For all other conditions,
refer to latest edition of ANSI Bulletin
Z223.1.
NOTE: Check with louver manufacturers for Net Free
Area of louvers. Correct for screen resistance to the
Net Free Area if a screen is installed. Check all local
codes applicable to combustion air.
Table 3. Minimum Recomended
Air Supply To Boiler Room.
Mighty Therm Hydronic Boiler
Window
Or Grill
Indoor
Room
WRONG
Page 7
2B-2. Venting
1. Laars boilers have built-in draft diverters for
natural draft operation and must not be
connected into any portion of a mechanical draft
system under positive pressure. The flue outlet
must be connected to a clear, unobstructed vent
of adequate capacity terminating above the
highest point of the building with an approved
vent cap. The venting system should be installed
according to the latest edition of ANSI Z223.1
and any local codes having jurisdiction and/or in
Canada follow CAN1-B149 standard.
IMPORTANT NOTE: Do not use sheet metal
screws at the snap lock joints of Type B gas vents.
2. Do not weld or fasten the vent pipe to the boiler
draft hood. The weight of the stack must not rest
on the boiler. The draft hood and boiler top must
be easily removable for normal boiler service
and inspection.
3. Avoid long horizontal runs of the vent pipe, and
too many 90° elbows, reductions and restrictions.
Horizontal runs should have at least a ¼" rise per
foot in the direction of flow. A vent connector
shall be supported for the design and weight of
the material employed to maintain clearances and
prevent physical damage and separation of joints.
4. Avoid terminating boiler vents near air
conditioning or air supply fans. The fans can
pick up exhaust flue products from the boiler and
return them inside the building, creating a
possible health hazard. A minimum of 4 feet
horizontal distance must be maintained from
electric meters, gas meters, and relief equipment.
5. Always use double-wall or insulated vent pipe
(Type B or equivalent). In cold weather,
uninsulated outside vents can chill the rising flue
products, blocking the natural draft action of the
venting system. This can create a health hazard
by spilling flue products into the boiler room.
6. Avoid oversize vent piping or extremely long
runs of the pipe which may cause excessive
cooling and condensation. Rule of Thumb: The
total length of the vent, including the connector
and any offset, should not exceed 15 feet for
every inch of vent diameter. Longer total lengths
shown in venting tables are based on maximum
capacity, not condensation factors.
7. When the installation of a draft fan is necessary
in the venting system to which a Laars boiler is
to be connected, the installation should be
engineered by competent personnel following
good engineering practices. The draft fan
supplier should be consulted for correct size. The
installation should be in accordance with the
latest edition of ANSI Z223.1 and any local
codes having jurisdiction, in Canada follow
CAN1-B149 standard. When a draft fan is
installed, a suitable draft switch must be used
and wired into the boiler control circuit at
terminal designated “Field Interlock,” to prevent
firing of the boiler unless a positive draft has
been established (see Figure 5).
2C. Installation of Outdoor Boilers
Caution
Outdoor installations are not recommended in areas
where the danger of snow blockage exists.
Figure 7. Method of Installing a Tee Sediment Trap.
1. Locate the boiler to provide the minimum
clearances as listed in Section 2A, “Placement of
Boiler.”
2. Do not locate the boiler in an enclosure or wall
recess. Avoid location where wind deflection off
structures might cause down draft. When such
Figure 6. Incorrect Outdoor Installation of Boiler.
Page 8
ly
LAARS Heating Systems
wind conditions are possible, locate the boiler
at least three (3) feet from the structures.
3. Never install the boiler under any kind of roof
overhang. Do not locate the boiler below or
adjacent to any doors, windows, louvers, grills,
etc. which communicate in any way with an
inhabited area of a building. Even though such
communication might be through another
structure such as a garage or utility room (see
Figure 6).
2D. Freeze Protection
Boiler installations are not recommended in
areas where the danger of freezing exists unless
proper precautions are made for freeze protection.
Maintaining a mixture of 50% water and 50%
ethylene glycol is the preferred method of freeze
protection for hydronic systems. This mixture will
protect the boiler to temperatures of about -35°F. To
get the desired temperature rise across the boiler
when this mixture is used, increase the G.P.M. flow
recommended for water by 15%. Increase the head
loss requirement by 20%.
4. The boiler and its individual shutoff valve must
be disconnected from the gas supply piping
system during any pressure testing of that system
at test pressures in excess of ½ psig. The boiler
must be isolated from the gas supply piping
system by closing its individual manual gas
shutoff valve during any pressure testing of the
gas supply piping system at test pressures equal
to or less than ½ psig.
5. Provide gas supply pressure to the boiler as
follows:
Natural Gas LPG
Min. (inches water column) 7 11
Max.(inches water column) 9 14
Note: The boiler and all other gas appliances
sharing the boiler gas supply line must be firing at
maximum capacity to properly measure the inlet
supply pressure. Low gas pressure could be an
indication of an undersize gas meter and/or obstructed
gas supply line.
2E. Gas Supply and Piping
Review the following instructions before
proceeding with the installation.
1. Verify that the boiler is fitted for the proper
type of gas by checking the rating plate. Laars
boilers are normally equipped to operate below
a 2000 foot altitude. Boilers equipped to
operate at higher altitudes have appropriate
stickers or tags attached.
2. Use the figures in Table 4 to provide adequate
gas piping (check local code for BTU capacity
required).
3. A trap (drip leg) must be provided ahead of the
gas controls (see Figure 7). Where required by
code, provide a second manual gas shutoff
valve. Do not remove manual valve furnished
with the boiler.
Gas Supp
To
Equipment
Inlet
Nipple
Cap
Inlet
Tee
Fitting
3" Min.
6. The correct burner manifold gas pressure is
stamped on the rating plate. The regulator is preset at the factory, and normally requires no
further adjustment.
7. The gas manifold and control assembly was
tested and conform to the safe lighting and other
performance criteria specified in the latest
editions of ANSI Z21.13 and CGA 3.3 Low
Pressure Boiler Standard.
Distance from Gas Meter or Last Stage Regulator
Indoor Outdoor 0-100' 100-200' 200-300'
Size Size Nat. Pro. Nat. Pro. Nat. Pro.
2000 ------ 2½ 2 3 2½ 3 3
2450 2200 3 2½ 3 2½ 3½ 3
3050 2800 3 2½ 3½ 3 3½ 3
3500 3200 3 2½ 3½ 3 4 3½
4050 3600 3½ 3 4 3½ 4 3½
4500 4000 3½ 3 4 3½ 5 4
5000 4500 4 3½ 4 3½ 5 4
NOTES:
These figures are based on 1/2" water column pressure drop.
Check supply pressure and local code requirements before
proceeding with work.
Pipe fittings must be considered when determining gas pipe sizing.
Figure 7. Method of Installing a Tee Sediment Trap.
Loading...