LAARS Mighty Max HH User Manual
Installation, Operation and Maintenance Instructions Document 2060D
Installation,
Operation and
Maintenance
Instructions for
Mighty Max
Hydronic Boilers
Model HH
Sizes 320M - 1000M
FOR YOUR SAFETY: This product must be installed and serviced by a professional service technician,
qualified in hot water boiler 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.
If the information in this manual is not
WARNING
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.
WHA T 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.
Assurez-vous de bien suivres les instructions
données dans cette notice pour réduire au
minimum le risque d’incendie ou d’explosion ou
pour éviter tout dommage matériel, toute
blessure ou la mort.
Ne pas entreposer ni utiliser d’essence ni
d’autres vapeurs ou liquides inflammables dans
le voisinage de cet appareil ou de tout autre
appareil.
QUE FAIRE SI VOUS SENTEZ UNE ODEUR DE GAZ:
• Ne pas tenter d’allumer d’appareils.
• Ne touchez à aucun interrupteur. Ne pas vous
servir des téléphones dansle bâtiment où vous
vous trouvez.
• Appelez immédiatement votre fournisseur de
gaz depuis un voisin. Suivez les instructions
du fournisseur.
• Si vous ne pouvez rejoindre le fournisseur de
gaz, appelez le sservice des incendies.
L’inst allation et l’entretien doivent être assurés par
un installateur ou un service d’entretien qualifié ou
par le fournisseur de gaz.
AVERTISSEMENT
H2090800D
Page 2
LAARS HEATING SYSTEMS
TABLE OF CONTENTS
SECTION 1.
General Information
1A. Introduction.................................................... 3
1B. Warranty........................................................3
1C. Technical Assistance.....................................3
SECTION 2.
Installation Instructions
2A. General Information....................................... 4
2B. Boiler Placement ........................................... 4
2C. Installation of Outdoor Boilers........................4
2D. Freeze Protection .......................................... 4
2E. Installation of Indoor Boilers...........................5
2E-1. Combustion Air Supply and Ventilation ..........5
2E-2. Removal of Existing Boiler............................. 5
2F. Gas Supply and Piping .................................. 6
2G. Water System Requirements.........................8
2G-1. Flow Requirements........................................8
2G-2. Variable Water Flow Systems........................8
2G-3. System Pressure Requirements ....................9
2G-4. Hot/Chilled Water Systems............................ 9
2G-5. Combined Space Heating/Potable
Water Heating Systems................................. 9
2H. Piping of System to Boiler .............................. 9
2I. Filling the System ........................................ 10
2J. Venting and Combustion Air Information ..... 10
2K. Top-to-Rear Vent Collar Conversion............12
2L. Venting ........................................................ 13
2L-1. Vertical Venting - Category I ........................ 13
2L-2. Vertical Venting - Non Category I.................13
2L-3. Vertical Venting - Non Category 1................13
2L-4. Side Wall Vent Terminal ..............................14
2M. Air for Combustion and Ventilation............... 14
2M-1. Air From Room ............................................ 15
2M-2. Ducted Combustion Air................................15
2M-3. Conversion for Ducted
Combustion Air ............................................ 15
2M-4. Combustion Air Piping ................................. 16
2N. Electrical Wiring ........................................... 16
SECTION 3.
Operating Instructions
3A. Start Up Requirements ................................ 16
3B. Hi-Limit checkout ......................................... 18
3C. Venturi and Gas Pressure
Regulator System ........................................ 18
3C-1. Overall Operation......................................... 18
3C-2. Venturi Adjustment ...................................... 18
3D. To Start Up System ..................................... 19
3D-1. Setting Temperature Controls...................... 20
3E. To Shut Down System ................................. 20
3F. Venturi Combustion Flow System ................ 20
3F-1. Pressure Measurement Ports ...................... 20
3F-2. Venturi Adjustment ...................................... 20
3F-3. Venturi Setup Procedure..............................22
SECTION 4.
Maintenance
4A. General Instructions..................................... 22
4B. Heat Exchanger........................................... 22
4B-1. Inspection of the Heat Exchanger................ 23
4B-1a. External heat Exchanger Inspection ............ 23
4B-1b. Internal Heat Exchanger Inspection ............. 23
4B-2. Cleaning the Heat Exchanger ...................... 23
4B-2a. Cleaning the Heat Exchanger - External...... 23
4B-2b. Cleaning the Heat Exchanger - Internal ....... 23
4C. Gas and Electric Controls ............................ 23
4D. Filter ............................................................ 24
4D-1. Filter Function .............................................. 24
4D-2. Filter Service................................................ 24
SECTION 5.
Troubleshooting
5A. Sequence of Operation................................ 24
5B. Venturi and Gas Pressure
Regulator System ........................................ 26
5B-1. Field Checkout............................................. 26
5C. Electrical Components ................................. 26
5C-1. General Troubleshooting ............................. 26
5C-2. Electrical Troubleshooting ........................... 26
SECTION 6.
Parts List for Mighty Max HH Boiler
6A. General Information..................................... 27
Mighty Max Hydronic Boiler
Page 3
SECTION 1.
General Information
1A. Introduction
This manual contains installation, operation and
maintenance instruction for the Mighty Max hydronic
boiler, Model HH, sizes 320M, 400M, 520M, 625M,
775M and 1000M. Review all application and
installation procedures completely before proceeding
with the installation. Consult the local factory
representative or Laars factory with any questions
regarding this equipment. Experience has shown that
most operating problems are caused by improper
installation. The HH boilers are offered in an indoor
version and an outdoor version (see Figure 1). Table 1
lists the input/output ratings for each boiler size.
The indoor version is convertible for outdoor use
with the installation of a conversion kit. See Section 6,
Parts List, for part number.
1B. Warranty
The Mighty Max HH boilers are sold with a
limited factory warranty. Details are specified on the
back cover of this manual.
Make all warranty claims to an authorized Laars
representative or directly to the factory. Claims must
include the heater serial number and model number
(this information can be found on the rating plate),
installation date, and name of the installer. Shipping
costs are not included in the warranty coverage.
Some accessory items are shipped in separate
packages. Inspect everything for damage immediately
upon delivery, and advise the transporter of any
shortages or damage. Any such claims should be filed
with the transporter. The transporter will not accept a
claim from the shipper, Laars.
The warranty does not cover damage caused by
improper installation, operation, or field modification.
1C. Technical Assistance
Consult the local factory representative or Laars
factory with any questions regarding the specification,
installation, and operation of Laars equipment. An
experienced technical support staff is ready to assist in
assuring the proper performance and application of
Laars products.
Boiler Input Output
Size BTU/h kW BTU/h kW
320M 320,000 94 272,000 80
400M 399,000 17 339,150 99
520M 520,000 152 442,000 130
625M 625,000 183 531,250 156
775M 775,000 227 658,750 193
1000M 1,000,000 293 850,000 249
Table 1. Input/Output Ratings.
INDOOR OUTDOOR
Front Side
(Water Connections)
Figure 1. Mighty Max HH Boiler Configuration.
Rear Side
(Opposite Water
Connections)
Page 4
LAARS HEATING SYSTEMS
SECTION 2.
Installation Instructions
2A. General Information
Install the Mighty Max HH boiler in accordance
with the procedures in this manual (or the Laars
warranty may be voided), local codes, and ordinances.
In the absence of such codes, install the heaters in
accordance with the latest edition of the National Fuel
Gas Code, ANSI Z223.1/National Fire Protection
Association (NFPA) 54. In Canada, the installation
must be in accordance with CAN1-B149.1 or .2 and
local codes. The authority having jurisdiction may
require the installation be in accordance with the
American Society of Mechanical Engineers (ASME)
Safety Codes for Controls and Safety Devices for
Automatically Fired Heaters, CSD-1, and in Canada,
Canadian Gas Association (CGA) 3.3. Any changes to
the boiler, its gas controls, gas orifices or wiring may
void the warranty. If field conditions require change,
consult the factory.
The Mighty Max HH boiler is designed-certified
for installation on a combustible floor. Do not install
the boiler directly on carpeting.
2B. Boiler Placement
2C. Installation of Outdoor Boilers
Caution
Outdoor installations are not recommended in
areas where the danger of snow blockage
exists.
1. Locate the boiler to provide at least the
minimum clearances as listed in Section 2B,
“Boiler Placement.” HH boilers require an
outdoor terminal kit when installed outdoors (see
Section 6, Parts List).
2. Do not locate the boiler in an enclosure or
through-wall recess. Avoid locations where wind
deflection off structures might cause down-draft.
When such wind conditions are possible, locate
the boiler at least 3 feet (.9m) from 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 2).
Clearance From Indoor Outdoor
Combustibles Inches mm Inches mm
Top 18 457 Unobstructed
Water Conn. Side 12 305 12 305
Opposite Side 6 152 6 152
Front Alcove Unobstructed
Rear 6 152 6 152
Vent *6* 152 —
Flooring Combustible Combustible
Service clearance = 24 in. (610mm) at front of boiler.
*1 in. (25mm) if double wall vent is used.
Table 2. Minimum Boiler Clearances
from Combustible Surfaces.
Locate the boiler to provide adequate clearances
on all sides for maintenance and inspection. There
must also be minimum distances maintained from
combustible surfaces (See Table 2).
The boiler must be isolated or otherwise
protected from any source of corrosive chemical
fumes, such as trichlorethylene, perchlorethylene,
chlorine, etc. Install the boiler so that the gas ignition
system components are protected from water
(drippings, spraying, rain, etc.) during operation and
service.
WINDOW
OR GRILL
WRONG
Figure 2. Incorrect Installation of Boiler.
INDOOR
ROOM
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%
properly inhibited HVAC glycol is the preferred
method of freeze protection for hydronic systems. (Do
not use automotive antifreeze.) This mixture will
protect the boiler to temperatures of about -35°F
(-37°C). To get the desired temperature rise across the
boiler when this mixture is used, increase the water
flow recommendation by 15%. Increase the head loss
requirement by 20%. Note: If your application does
Mighty Max Hydronic Boiler
Page 5
not require the full freeze protection of a 50%/50%
mixture, it is beneficial to use a maximum 30% glycol
solution. This mixture will protect the boiler to
temperatures of about 5°F (-15°C), and will serve as
burst protection for boilers that are not in use.
2E. Installation of Indoor Boilers
2E-1. Combustion Air Supply and
Ventilation
There are a variety of options available to the
installer when it comes to venting and combustion air;
venting can be vertical or horizontal, it can originate
at the top of the boiler or the back, and combustion air
can be obtained from the room where the boiler is
installed or ducted directly to the boiler from
outdoors. See Sections 2J through 2M for details.
2E-2. Removal of Existing Boiler
At the time of removal of an existing boiler, the
following steps shall be followed with each appliance
remaining connected to the common venting system
placed in operation, while the other appliances
remaining connected to the common venting system
are not in operation.
1. Seal any unused openings in the common
venting system.
2. Visually inspect the venting system for proper
size and horizontal pitch and determine there is
no blockage or restriction, leakage, corrosion
and other deficiencies which could cause an
unsafe condition.
3. Insofar as is practical, close all building doors
and windows, and all doors between the space in
which the appliances remaining connected to the
common venting system are located and other
spaces of the building. Turn on clothes dryers
and any appliance not connected to the common
venting system. Turn on any exhaust fans, such
as range hoods and bathroom exhausts so they
will operate at maximum speed. Do not operate a
summer exhaust fan. Close fireplace dampers.
4. Place in operation the appliance being inspected.
Follow the lighting instructions. Adjust
thermostat so appliance will operate
continuously.
5. Test for spillage at the draft hood relief opening
if the appliance is equipped with a drafthood,
after 5 minutes of main burner operation. Use
the flame of a match or candle, or smoke from a
cigarette, cigar or pipe.
6. After it has been determined that each appliance
remaining connected to the common venting
system properly vents when tested as outlined
above, return door, windows, exhaust fans,
fireplace dampers and any other gas-burning
appliances to their previous condition of use.
7. Any improper operation of the common venting
system should be corrected so the installation
conforms with the National Fuel Gas Code,
ANSI Z223.1. When resizing any portion of the
common venting system, the common venting
system should be resized to approach the
minimum size as determined using the
appropriate Tables in Appendix G in the
National Fuel Gas Code, ANSI Z223.1.
In Canada, at the time the boiler is removed from
common venting system, the common venting system
should be resized so the installation conforms to
CAN/CGA B149.1 or .2.
2E-2. Removal of Existing Boiler
Au moment du retrait d’une chaudière existante,
les mesures suivantes doivent être prises pour chaque
appareil toujours raccordé au système d’evacuation
commun et qui fonctionne alors que d’autres appareils
toujours raccordés au système d’évacuation ne
fonctionnent pas:
1. Sceller toutes les ouvertures non utilisées du
système d’évacuation.
2. Inspecter de façon visuelle le système
d’évacuation pour déterminer la grosseur et
l’inclinaison horiztonale qui conviennent et
s’assurer que le système est exempt
d’obstruction, d’étranglement, de fuite, de
corrosion et autres défaillances qui pourraient
présenter des risques.
3. Dans la mesure du possible, fermer toutes les
portes et les fenêtres du bâtiment et toutes les
portes entre l’espace, où les appareils tojours
raccordés et les autres espaces du bâtiment.
Mettre en marche les sécheuses, tous les
appareils non raccordés au système d’évacuation
commun et tous les ventilateurs d’extraction
comme les hottes de cuisinère et les ventilateurs
des salles de bain. S’assurer que ces ventilateurs
fonctionnent à la vitesse maximale, Ne pas faire
fonctionner les ventilateurs d’été. Fermer les
registres des cheminées.
4. Mettre l’appareil inspecté en marche. Suivre les
instructions d’allumage. Régler le thermostat de
façon continue.
5. Faire fonctionner le brûleur principal pendant 5
min ensuite déterminer si le coupe-tirage
déborde à l’ouverture de décharge. Utiliser la
flamme d’une allumette ou d’une chandelle ou la
afumée d’une cigarette, d’une cigare ou d’une
pipe.
6. Une fois qu’il a été déterminé, selon la méthode
indiquée ci-dessus, que chaque appareil raccordé
Page 6
LAARS HEATING SYSTEMS
Distance from Gas Meter or Last Stage Regulator
0-100 feet 100-200 feet 200-300 feet
0-30m 30-60m 60-90m
Natural Propane Natural Propane Natural Propane
Size in.
320M
400M
520M
625M
775M
1000M
Notes: 1. These numbers are based on 1/2 inch (13mm) water column pressure drop.
1.25
1.25
1.50
1.50
2.00
2.00
2. Check supply pressure and local code requirements before proceeding with work.
3. Pipe fittings must be considered when determining gas pipe sizing.
mm
32
32
38
38
51
51
in.
1.25
1.25
1.25
1.25
1.50
1.50
Table 3. Natural Gas and Propane, Pipe Size Requirements.
au systéme d’évacuation est mis à l’air libre de
façon adéquate. Remettre les portes et les
fenêres, les ventilateurs, les registres de
cheminées et les appareils au gaz à leur position
originale.
7. Tout mauvais fonctionnement du systéme
d’évacuation commun devrait êvacuation
commun devrait être corrigé de façon que
l’installation soit conforme au National Fuel
Gas Code, ANSI Z223.1/NFPA 54 et (ou) aux
codes d’installation CAN/CGA-B149. Si la
grosseur d’une section du systéme devrait être
modifié ppour respecter les valeurs minimales
des tableaux pertinents de l’appendice F du
National Fuel Gas Code, ANSI Z223.1/NFPA 54
et (ou) des codes d’installation CAN/CGA-B149.
mm
32
32
32
32
38
38
in.
1.50
1.50
2.00
2.00
2.00
2.50
mm
38
38
51
51
51
64
in.
1.25
1.25
1.50
1.50
1.50
2.00
mm
32
32
38
38
38
51
operate at high altitudes have appropriate
stickers or tags attached.
3. The figures in Table 3 should be used to size the
gas piping from the gas meter to the boiler.
Check local codes for BTU/h capacity required.
4. Install a sediment trap (drip leg) ahead of the gas
controls (see Figure 4). Fit the trap with a
threaded cap which can be removed for cleaning.
5. When required by code, install a second manual
gas shutoff valve. Do not remove manual shutoff
valve supplied with the boiler.
6. Disconnect the boiler and its individual shutoff
valve from the gas supply piping system during
pressure testing of the system at pressures higher
than 1/2 psi (3.5 kPa). Isolate the boiler from the
gas supply piping system by closing its
2F. Gas Supply and Piping
Review the following instructions before
continuing the installation.
1. Gas piping installation must be in accordance
with the latest edition of ANSI Z223.1/NFPA 54.
In Canada, the installation must be in accordance
with CAN1-B149.1 or .2 and all local codes that
apply. See Figure 3 for boiler gas valve
individual manual gas shutoff valve during any
pressure testing of the gas supply piping system
at test pressures equal to or less than 1/2 psi
(3.5 kPa).
7. Gas supply pressures to the boiler are listed in
Table 4.
Supply Pressure
Water Column
arrangement.
2. Check the rating plate to make sure the boiler is
Minimum 5
fitted for the type of gas being used. Laars
boilers are normally equipped to operate below a
2000 foot (610m) altitude. Boilers equipped to
Maximum 9
Table 4. Gas Supply Pressure Requirements.
in.
1.50
2.00
2.00
2.00
2.50
3.00
mm
38
51
51
51
64
76
Natural Gas Propane Gas
in.
mm
127
229
in.
1.50
1.50
1.50
2.00
2.00
2.50
in.
9
14
mm
38
38
38
51
51
64
mm
229
356
Mighty Max Hydronic Boiler
Air Shutter
Enclosure
Filter
Housing
Automatic,
Regulator
and
Redundant
Gas Valve
Mixture
Plenum
Venturi
Blower
Motor
Filter
Housing
Venturi
Automatic
and
Redundant
Gas Valve
Mixture
Plenum
Air Shutter
Enclosure
Blower
Motor
Regulator
Manual Gas
Valves When
Used On
Canadian Unit
or U.S.Unit
Requiring
CSD-1 Code
Filter
Housing
Venturi
Air Shutter
Enclosure
Mixture
Plenum
Blower
Motor
Automatic
Main
Gas Valves
Page 7
Regulator
Manual Gas
Valves When
Used On
Canadian Unit
or U.S.Unit
Requiring
CSD-1 Code
SIZES:
320M, 400M
SIZES:
520M, 625M
SIZES:
775M, 1000M
Note: The above diagram is a representation. Actual venturi assembly may vary depending on boiler size.
Figure 3. Boiler Gas Valve Arrangement.
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
Gas Supply
Inlet
indication of an undersize gas meter and/or obstructed
gas supply line.
8. Do not exceed the maximum inlet gas pressures
Tee
Fitting
specified. Excessive pressure will result in
damage to the heater's gas controls. The
minimum pressures specified are for gas input
3 In.
(76mm) Min.
Nipple
adjustment.
9. The correct differential gas pressure is stamped
on the rating plate. The regulator is preset at the
Cap
factory, but may need adjustment for altitude per
Section 3.
10. Before operating the heater, test the complete
Figure 4. T-Fitting Sediment Trap Installation.
gas supply system and all connections for leaks
using a soap solution.
To Equipment
Inlet
Caution
Since some leak test solutions (including soap
and water) may cause corrosion or stress
cracking, rinse the piping with water after
testing.
Page 8
LAARS HEATING SYSTEMS
2G. Water System Requirements
2G-1. Flow Requirements
The Model HH 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 flow (see Table 5). The
temperature rise across the boiler should never exceed
40°F (22°C).
2G-2. Variable Water Flow Systems
There can be reduced water flow through the
boiler in heating systems using zone valves, zone
pumps or 3-way valves. This can result in a high
temperature rise across the boiler. Laars recommends
primary-secondary pumping for all variable flow
systems. The boiler pump in a primary-secondary
system maintains constant flow through the boiler
even though the system flow is variable. In a primarysecondary system the pressure drop of the boiler is not
added to the system (see Figure 5).
TEMPERA TURE RISE IN DEGREES (°F / °C )
10°F
6°C
15°F
MODEL
LPS H/L m
3.41
4.29
5.55
6.69
8.33
10.73
3.4
8.0
2.7
3.7
6.9
11.4
GPM H/L ft.
36
45
58
70
87
113
5.0
11.5
4.0
5.7
9.4
16.5
HH0320M
HH0400M
HH0520M
HH0625M
HH0775M
HH1000M
GPM H/L ft.
54
68
88
106
132
170
11.2
26.2
8.9
12.2
22.5
37.3
Flow High Normal Low
NOTES: Sizes 320M and 400M use 4-pass heat exchangers; 520M, 625M and 775M use 2-pass heat exchangers.
*Pressure drop (head loss) through the boiler, expressed in ft. of H2O.
Shaded area is the recommended flow and temperature rise. Minimum inlet temperature is 105°F.
8°C
LPS H/L m
2.27
2.84
3.66
4.42
5.49
7.13
1.5
3.5
1.2
1.7
2.9
5.0
20°F
GPM H/L ft.
27
34
44
53
65
85
2.8
6.6
2.6
3.3
5.2
9.4
11°C
LPS H/L m
1.70
2.15
2.78
3.34
4.10
5.36
0.9
2.0
0.8
1.0
1.6
2.9
WARNING: This drawing shows suggested
piping configuraiton and valving. Check with
local codes and ordinances for additional
requirements.
Boiler Circulation
12"
Max.
LEGEND:
Thermometer
Temperature
Sensor
Globe Valve
Check Valve
Pressure Reducing Valve
w/Fast Fill Bypass
Purge
Valve
Expansion T ank
with Air Scoop and
Auto Air Vent
3-Way Valve
Valve
Pump
Pump
Table 5. Temperature Rise.
12"
Max.
12"
Max.
Cold Water
Make-Up
System Pump
12"
Max.
Boiler circuit piping must be equal to or larger than
boiler water connection size.
Boiler circulation pump sized for flow through
boiler.
Dotted devices indicate alternate locations.
Figure 5. Primary-Secondary Plumbing.
Mighty Max Hydronic Boiler
Page 9
2G-3. System Pressure Requirements
The Model HH boilers are designed to operate
on closed, pressurized systems. Maintain a minimum
of 12 psi (81.8 kPa) on the system where boiler supply
water temperature is 200°F (93°C) or less. If higher
temperatures are required, the minimum system
pressure should be at least 15 psi (102.2 kPa) 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 (82°C), and a minimum of 5 psi
(34.1 kPa) static head is maintained at the boiler.
2G-4. Hot/Chilled Water Systems
When a boiler is connected to an air
conditioning system where the same water is used for
heating and cooling, you must prevent chilled water
from entering the boiler. When changing such a
system from cooling to heating, allow the chilled
water to circulate through the building, after the
chiller has been turned off, for a period long enough
for the water to warm up to at least 105°F (41°C)
before the water flows into the boiler. It is equally
important to prevent hot water from entering the
chiller. The system shown in Figure 6 is suggested to
make sure the system water is neither too hot nor too
cold when a changeover takes place. When a boiler is
connected to heating coils located in air handling units
(where they may be exposed to refrigerated air
circulation), install 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.
Boilers installed in violation of the foregoing may
void the warranty.
2G-5. Combined Space Heating/Potable
Water Heating Systems
When using the Mighty Max boiler as a source
of heat for a combined space heating/potable water
heating system, be sure to follow the instructions of
the space heating system.
Do not use water piping, fittings, valves, pumps,
and any other components which are not compatible
with potable water.
Do not connect the heater, which will be used to
supply potable water, to any heating system or
components previously used with a nonpotable water
heating system.
Do not add boiler treatment or any chemicals to
the heating system piping, since the piping contains
water for potable use.
Do not use solder containing lead in the potable
water lines.
Some jurisdictions may require a backflow
preventer in the cold water line. In such cases,
pressure relief valve may discharge water due to
expansion. An expansion tank approved for potable
water will eliminate this condition. Follow the
manufacturer's instructions for installation of the
expansion tank.
Suggested Wiring Diagram For
Tempering System Water at
Changeover From Heating To Cooling
DPDT Manual or Automatic
Change-Over Switch
DPDT - Set at Change-Over
Temperature
115/24V
Transformer
From
Chiller
3-Way Valve No. 1
Change-Over
(Heating and Cooling)
Figure 6. Boiler-Chiller Installation.
Valve Motors
2-Pos
3-Wire - 24V
From
Boiler
3-Way Valve No. 2
To By-Pass
Both Heater and
Chiller
Clock Timer
Auto-Resetting
Set at 15 Minute SPDT
To Boiler
and
Chiller
By-Pass
From
System
To
System
2H. Piping of System to Boiler
1. Be sure to provide gate valves at the inlet and
outlet to the boiler so it can be readily isolated
for service.
2. The pressure relief valve installed in the tapped
opening provided in the outlet header must be
piped, but not fastened, to a drain or floor sink.
The drain pipe must be the same size as the valve
outlet and must pitch downward from the valve. If
the PRV supplied with the boiler is not factory
installed, install it in the front header consistent
with the ANSI/ASME Boiler and Pressure Vessel
Code, Section IV. Pay special attention to relief
valve settings in installations where the boiler is
located on the ground floor of a tall building, or
where the operating temperature of the boiler is
above 210°F (99°C). In both instances, the static
pressure of the system is elevated and could cause
the relief valve to leak and bring considerable raw
water into the system. Where no special setting of
the relief valve is ordered, the factory will furnish
a 75 psi (511.5 kPa) setting. Never reduce the
relief valve opening. If necessary, install the relief
valve in a Tee immediately past the boiler outlet.
Page 10
LAARS HEATING SYSTEMS
Air Changer
and Tank
Drainer
Make-Up
Water
Supply
Check
Valve
Pressure
Reducing
Valve
Blow Down
Valve
Strainer
NOTES: Select Method 1 or 2 when using low water cutoff accessory:
1. Under Method 1, the low water cutoff is furnished by Laars and shipped
as a separate item for fieldinstallation.
2. Under Method 2, electronic low water cutoff isinstalled, wired and tested
on boiler in Laars factory.
3. Preferred locaiton of system pump is shown. Compression tank must
always be on suction side of pump.
Figure 7. Boiler Piping.
To Drain
Method 1
To
System
Pump
Expansion
Tank
Method 2
To
Drain
Thermometer
Temperature
and Pressure
Gauge
3. Provide a boiler installed above radiation level
with a low water cutoff device either as part of
the boiler or at the time of boiler installation (see
Figure 7).
4. Install manual and/or automatic bleeding devices
at high points in the system to eliminate air.
Install a correctly sized expansion or
compression tank with suitable air charger and
tank drainer, as appropriate.
5. Support the weight of all water and gas piping by
suitable hangers or floor stands.
6. Check piping diagrams with local applicable
plumbing, heating and building safety codes.
2I. Filling The System
1. Ensure the system is fully connected. Close all
bleeding devices and open make-up water valve.
Allow system to fill slowly.
2. If make-up water pump is employed, adjust
pressure switch on pumping system to provide a
minimum of 12 psi (81.8 kPa) at the highest
point in the heating loop.
3. If a water pressure regulator is provided on the
make-up water line, adjust the pressure regulator
to provide at least 12 psi (81.8 kPa) at the
highest point in the heating loop.
4. Open bleeding devices on all radiation units at
the high points in the piping throughout the
system, unless automatic air bleeders are
provided at such points.
5. Run system circulating pump for a minimum of
30 minutes with the boiler shut off.
6. Open all strainers in the circulating system,
check flow switch operation, and check for
debris.
7. Recheck all air bleeders as described in Step 4
above.
8. Check liquid level in expansion tank. With the
system full of water and under normal operating
pressure, the level of water in the expansion tank
should not exceed 1/4 of the total, with the
balance filled with air.
9. Start up boiler according to procedure described
in Section 3A. Operate the entire system,
including the pump, boiler, and radiation units
for one (1) hour.
10. Recheck the water level in the expansion tank. If
the water level exceeds 1/4 of the volume of the
expansion tank, open the tank drainer and drain
to that level.
11. Shut down the entire system and vent all
radiation units and high points in the system
piping as described in Step 4 above.
12. Close make-up water valve and check strainer in
pressure reducing valve for sediment or debris
from the make-up water line. Reopen make-up
water valve.
13. Check gauge for correct water pressure and also
check water level in the system. If the height
indicated above the boiler insures that water is at
the highest point in the circulating loop, then the
system is ready for operation.
14. Within three (3) days of start-up, recheck all air
bleeders and the expansion tank as described in
Steps 4 and 8 above.
IMPORTANT:
The installer is responsible for identifying to the
owner/operator the location of all emergency
shutoff devices.
2J. Venting and Combustion Air
Information
Provisions for venting and supply of air for
venting and combustion must be done in accordance
with these instructions and applicable requirements of
the latest edition of ANSI Z223.1/NFPA 54. In
Canada, installation must be in accordance with CAN/
CGA B149.1 or .2, and applicable local codes.
There are a variety of ways to provide venting
and combustion air for the boiler (see Figure 8).
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