LAARS Mighty Therm AP Installation Manual
Installation and Operation Instructions Document 3006T
Installation and Operation
Instructions for
Mighty Therm
Pool Heating Boiler
Model AP
Sizes 500 - 1825
These instructions are to be stored in the
pocket provided on the heater.
FOR YOUR SAFETY: This product must be installed and serviced by a professional service technician,
qualifi ed in hot water heater installation and maintenance. Improper installation and/or operation could
create carbon monoxide gas in fl ue 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 fi re or explosion may
result causing property damage, personal
injury or loss of life.
Do not store or use gasoline or other
fl ammable 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 fi re department.
Installation and service must be performed
by a qualifi ed 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 infl ammables 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’installation et l’entretien doivent être assurés par un
installateur ou un service d’entretien qualifi é ou par le
fournisseur de gaz.
AVERTISSEMENT
H0067300T
Page 2
LAARS Heating Systems
Table of Contents
Section 1
General Information
1.1 Introduction ....................................................3
1.2 Heater Identifi cation .......................................3
1.3 Primary/Secondary Pump and Piping ............3
1.4 Certifi cations ..................................................3
1.5 Engineering Assistance ................................. 3
Section 2
Installation
2.1 Heater Placement ..........................................4
2.2 Installation of Indoor Heaters ......................... 4
2.2.1 Combustion Air Supply ..................................4
2.2.2 Venting ...........................................................5
2.2.3 Common Venting System
Test Procedure ..............................................6
2.2.3 Instructions Relatives au Test des
Systèmes à Évent Commun ..........................6
2.3 Installation of Outdoor Heaters ......................7
2.4 Gas Supply and Piping ..................................7
2.5 Electrical Wiring .............................................8
2.6 General Piping Instructions ...........................9
2.7 Heater By-Pass Piping ..................................9
2.8 Temperature Sensor Placement
and Installation ..............................................9
2.9 Automatic Chlorinators ................................10
Section 3
Operation
3.1 Controls - General .......................................10
3.2 Initial Start-Up .............................................. 11
3.3 Safety Shutoff Component Checkout .......... 12
3.4 Inlet Temperature and
Temperature Rise Adjustment .....................13
3.5 Heater Shut Down ....................................... 13
3.6 Spring and Fall Operation
Stand-by Service .........................................13
3.7 Winter Operation Complete Shutdown ........ 14
3.8 Time Clock Operation ..................................14
3.9 Therapeutic Pools (Spas) ............................ 14
Section 4
Maintenance ..................................................... 15
Section 5
Troubleshooting
.............................................16
Section 6
Parts Description and Order Numbers ..18
Mighty Therm Commercial Pool Heating Boiler
Page 3
Section 1
General Information
1.1 Introduction
This manual provides information for the installation
and operation of Laars Model AP pool heating boilers.
It is strongly recommended that all application and
installation procedures be reviewed completely before
proceeding with the installation. Consult the Laars
factory, or local factory representative, with any problems
or questions regarding this equipment. Experience has
shown that most problems are caused by improper
installation, not system design.
Some accessory items are shipped in separate packages.
Verify receipt of all packages listed on the packing slip.
Inspect everything for possible damage upon delivery,
and inform the carrier of any shortages or impairments.
Any such claims should be fi led with the carrier. The
carrier, not the shipper, is responsible for shortages and
damage to the shipment whether visible or concealed.
WARNING
The model AP commercial pool heater must
be used on potable water only. For heating
pools containing salt water, a specially
equipped heater must be used; consult your
distributor or factory representative. The
pool heater must be installed in accordance
with the procedures outlined in this manual.
The warranty does not apply to heaters 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, National Electrical Code
ANSI/NFPA 70. In Canada, the installation must conform
with the latest edition of CSA B149 requirements.
When required by the authority having jurisdiction,
the installation must conform to American Society of
Mechanical Engineers safety codes for controls and
safety devices for automatically fi red heaters No. CSD-1,
and in Canada CSA 3.3. Any modifi cation of the heater,
its gas controls, gas orifi ces, wiring or drafter diverter
may void the Laars warranty. If fi eld conditions require
such modifi cations, consult the factory.
1.2 Heater Identifi cation
Consult rating plate on the heater. Shown below is a
breakdown of the model nomenclature. Laars commercial
pool heating boilers are available in two confi gurations:
an indoor version and an outdoor version. Outdoor
models are not available in Canada.
1.3 Primary/Secondary Pump and Piping
All models are supplied with integrally mounted pumps.
The 1825 models use a 3/4 HP pump and all other models
are supplied with 1/2 HP pumps. These pumps are sized
for the pressure drop through the heat exchanger and
through the bypass piping as shown in Figure 10.
Any deviations from the arrangement shown may
increase the head on the pump, reduce fl ow and hinder
performance (see Section 2.7). For spas see Section 3.9.
This piping arrangement and the integral pump allow hot
water to be recirculated to the heater inlet, thus raising
the inlet temperature and greatly reducing condensation.
1.4 Certifi cations
All models are design-certifi ed by CSA for natural or
propane gas and conform to ASME Code requirement for
160 PSI water pressure.
1.5 Engineering Assistance
Consult the factory or distributor regarding any questions
or problems which arise in the specifi cation, installation
or operation of Laars equipment. An experienced
engineering staff is ready to assist in assuring the proper
performance and application of Laars products.
1 2 3 4 5 6 7 8 9 10 11 12 13 14
MODEL
AP-POOL
Figure 1. Heater Identifi cation (Model Nomenclature)
SIZE
BTU/HR X 1000
0500
0600
0715
0850
0999
1010
1200
1430
1670
1825
I-INDOOR
E-OUTDOOR
FUEL
N-NATURAL
P-PROPANE
IGNITION
04-SPARK 110V
09-SPARK 24V
11-SPARK 24V
16-STND. PILOT
FIRING MODE
ON/OFF
C
VERSION
1 - 8 TUBE
B-10 TUBE
HEAT EXCHANGER
C-GLASS LINED/COPPER
N-GLASS LINES/CU-NI
K-BRONZE/COPPER
S-BRONZE/CU-NI
REVISION
P-PUMP (U.S.)
Q-PUMP (CAN)
Page 4
LAARS Heating Systems
Section 2
Installation
2.1 Heater Placement
The pool heater must be placed to provide specifi c
clearances on all sides for maintenance and inspections.
There must also be minimum distances maintained from
combustible surfaces. These clearances also apply to
noncombustible materials because the pool heater requires
air circulation for proper operation.
The pool heater should be mounted on a level surface. An
integral base for an installation on combustible fl ooring is
provided as standard equipment on outdoor models. For
indoor models, special base rails part number 10539000
must be used for combustible fl ooring.
Do not install a pool heater on carpeting.
Under the national Fuel Gas Code, ANSI Z223.1, it
is permissible to place the heater on fl oors other than
noncombustible when the installation complies with the
American Insurance Code. Figures 2, 3, 4 and 5 show
common installation on combustible fl ooring.
2.2 Installation of Indoor Heaters
Locate the pool heater to provide adequate clearance
for inspection and service on all sides. See Table 1. For
alcove installation, see Figure 6.
Install indoor heaters on a waterproof fl oor with an
adequate fl oor drain and a 6" (152mm) minimum curb on
all four sides to protect the building if heater repairs are
required. The manufacturer will not be held liable for
any water damage in connection with this heater.
2.2.1 Combustion Air Supply
The heater location must provide suffi cient air supply
for proper combustion and ventilation of the surrounding
area as outlined in the latest edition of ANSI standard
Z223.1, and any local codes that may be applicable. Inadequate combustion air supply may result in incomplete
combustion, sooting of the heat exchanger, and unsafe
operation of the heater.
Clearance Indoor Outdoor
from in. mm in. mm
Top 30 762 unobstructed
Water Conn. side 12* 305 24 610
Pump side 6* 152 24 610
Front Alcove* unobstructed
Rear 8 203 24 610
Vent pipe** 6 152 - - -
Hot water pipes per code per code
* Water connection and pump side clearances of 24"
(610mm) and front clearances of 48" (1219mm) will allow
easier service access.
** Using type B vent (refer to Manufacturer's Instructions).
Table 1 - Minimum Heater Clearances
from Adjacent Surfaces
Figure 2 - Typical Heater Installation on Concrete Slab
a. Conventional Ventilation
In the United States, the most common of these requirements specify that boiler rooms should be provided with
two permanent air supply openings communicating directly through the wall to outside air one within 12 inches
(305mm) of the ceiling, and the other within 12 inches
(305mm) of the fl oor. Each opening should have a minimum free area of one square inch (6.5 sq. cm) per 4,000
BTU/hr input of the total input rating of all appliances in
the enclosed area. See Table 2 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.
Pool heaters installed in vaults (“pits”) must have
combustion air ducted to bottom of the vault, even if the top
is unobstructed. Ducting should be sized for a minimum of
one square inch (6.5 sq. cm) per 2,000 BTU/hr input of the
Figure 3 - Typical Heater Installation on Roof
Using Raised Platform (Wood)
total input rating of all appliances in the vault. Contact the
Service Department for more information.
In Canada, Table 2 does not apply. Consult local building
codes or, in the absence of such requirements, follow
CSA B149 standard.
Mighty Therm Commercial Pool Heating Boiler
Page 5
Water
Heater
Figure 4 - Typical Heater Installation on Roof
Using 4x4 Stringer
Base must extend out
min. 12" (305mm) on
all sides of
heater frame.
Concrete blocks or tile min. 7" (178mm)
high with 3" (76mm) 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 5 - Installation on Concrete Blocks or Tile
20 ga. min.
galvanized sheet
metal
under entire
heater.
b. Forced-Air Ventilation
In the United States: 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 fl ue products to accumulate
in the boiler room. Additional air must be supplied to
compensate for such exhaust. The information in Table
2 is not applicable in installations where exhaust fans or
blowers of any type are used. Such installations must be
designed by qualifi ed engineers.
In Canada: follow Canadian standard, CSA B149 or local
codes.
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 heater, a suitable switch or interlock must be wired
into the heater control circuit to prevent the heater from
fi ring unless the blower is operating.
The heater must be completely isolated and protected
from any source of corrosive chemical fumes such as
trichlorethylene, perchloroethylene, chlorine, etc.
CLOSET INSTALLATION
(UNACCEPTABLE)
A closet is any 4 sided enclosure
which is less than 16* times the total
volume of all the gas fired appliances
within the enclosure.
Water
Heater
* When the ceiling height exceeds 8 feet, you are only allowed to consider 8
feet when calculating the total volume of the enclosure.
Figure 6 - Alcove Installation
ROOM INSTALLATION
(ACCEPTABLE)
A room is any enclosure which is at
least 16* times greater than the total
volume of all the gas fired appliances
within the enclosure.
ALCOVE INSTALLATION
(ACCEPTABLE)
An alcove suitable for the installation
of a water heater is a restricted section
of a room not separated from the
room by a door or partition and which
meets the minimum clearances for
the specific model water heater listed
below.
WARNING
Chemicals stored in the equipment room may
cause corrosion. Sodium hypochlorite feeders,
vented tablet containers, pellet salt and other
chemicals may off-gas into the air in the room
and be drawn into the combustion and dilution
air, corroding the pool heater's metallic parts.
Corrosion damage is not covered under the
limited warranty.
2.2.2 Venting
Laars heaters have built-in draft diverters for natural draft
operation and must not be connected to any portion of a
mechanical draft system under positive pressure. The fl ue
outlet must be connected to a clear, unobstructed vent of
adequate capacity ending 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/or, in Canada, CSA B149 and any local
codes having jurisdiction.
Do not weld or fasten the vent pipe to the heater
drafthood. The weight of the stack must not rest on the
heater. The drafthood and heater top must be easily
removable for normal heater service and inspection.
IMPORTANT NOTE: Do not use sheet metal screws at
the snap lock joints of Type B gas vents.
Avoid using long horizontal runs of the vent pipe, and too
many 90° elbows, reductions or restrictions. Horizontal
runs should have at least a 1/4" (6mm) rise per foot in the
Page 6
LAARS Heating Systems
direction of fl ow. A vent connector should be supported
for the design and weight of the material used to maintain
clearances and prevent physical damage and separation
of joints.
Avoid terminating heater vents near air conditioning
or air supply fans. The fans can pick up exhausted fl ue
products from the heater and return them inside the
building creating a possible health hazard. A minimum
of 4 feet (1.2m), in Canada 6 feet (1.8m), horizontal
distance must be maintained from electrical meters, gas
meters, and relief equipment.
Always use double-wall or insulated vent pipe (Type B
or equivalent). In cold weather, uninsulated outside vents
can chill the rising fl ue products blocking the natural
draft action of the venting systems. This can create a
health hazard by spilling fl ue products in the boiler room.
When the installation of a draft fan is necessary
in connecting a venting system to a Laars heater,
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/or, in Canada, CSA B149
and any local codes having jurisdiction. When a draft
fan is installed, a suitable draft switch must be wired into
the heater control circuit at terminal designated "Field
Interlock" to prevent fi ring of the heater unless a positive
draft has been established.
2.2.3 Common Venting System
Test Procedure
At the time of the removal of an existing heater, the
following steps shall be followed with each appliance
remaining connected to the common venting system.
During the testing of each unit, the other appliances
remaining connected to the common venting system
should not be operated.
1. Seal any unused openings in the common venting
system.
2. Visually inspect the venting system for proper size
and horizontal pitch. Determine that there is no
blockage or restriction, leakage, corrosion, or other
defi ciencies which could cause an unsafe condition.
3. Insofar as it is practical, close all building doors and
windows. Also close all doors between the space
in which the appliances remaining connected to the
common venting system are located and the other
spaces of the building. Turn on any clothes dryer
and any appliance not connected to the common
venting system. Turn on any exhaust fans, in clud ing
range hoods and bath room ex hausts, so they will
operate at maximum speed. Do not operate a
summer exhaust fan. Close all fi replace dampers.
4. Place in operation the appliance being in spect ed.
Follow the lighting instructions for the unit.
Adjust the thermostat so the appliance will operate
continuously.
5. Test for spillage at the draft hood relief opening
after 5 minutes of main burner operation. Use
the fl ame 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
doors, windows, exhaust fans, fi replace dampers and
any other gas-burning appliance 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 and/or CSA B149, Installation Codes. 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 and/or CSA B149
Installation Codes.
2.2.3 Instructions Relatives au Test des Systèmes à
Évent Commun
Au moment du restrait dʼune chaudière existante, les
mesures suivantes doivent être prises pour chaque
appareil toujours reccordé au système dʼévacuation ne
fonctionnet pas:
1. Sceller toutes les ouvertures non utilisées du
systèmes dʼévacuation.
2. Inspecter de façon visuelle le système dʼévacuation
pour déterminer la grosseur et lʼinclinaison
horizontale qui conviennent et sʼassurer que le
système est exempt dʼobstruction, dʼétranglement,
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
lʼespace où les appareils toujours raccordés au
système dʼévacuation sont installés et les autres
espaces du bâtiment. Mettre en marche les sécheuses, tous les appareils non raccordés au système
dʼévacuation common et tous les ventilateurs
dʼextraction comme les hottes de cuisinière et les
ventilateurs des salles de bain. Sʼassurer que ces
ventilateurs fonctionnent à la vitesse maximale. Ne
pas faire fonctionner les ventilateurs dʼété. Fermer
les registres des cheminées.
4. Mettre lʼappareil inspecté en marche. Suivre les
instructions dʼallumage. Régler le thermostat de
façon que lʼappareil fonctionne de façon continue.
5. Faire fonctionner le brûleur principal pendant 5 min
ensuite, déterminer si le coupe-tirage déborde à louverture
de décharge. Utiliser la fl amme dʼune chandelle ou la
fumée dʼune cigarette, dʼune cigare ou dʼune pipe.
6. Une fois quʼil a été déterminé, selon la méthode
indiquée ci-dessus, que chaque appareil raccordé
au systéme dʼévacuation est mis à lʼair libre de
façon adéquate. Remettre les portes et les fenêtres,
les ventilateurs, les registres de cheminées et les
appareils au gaz à leur position originale.
Mighty Therm Commercial Pool Heating Boiler
Page 7
7. Tout mauvais fonctionnement du systéme
dʼévacuation commun devrait être corrigé de façon
que lʼinstallation soit conforme au National Fuel Gas
Code, ANSI.Z223.1 et (ou) aux Codes dʼInstallation
CSA B149. Si la grosseur dʼune section du système
dʼévacuation doit être modifi ée, le système devrait
être modifi é pour respecter les valeurs minimales des
tableaux pertinents de lʼappendice G du National
Fuel Gas Code, ANSI Z2231.1 et (ou) des Codes
dʼInstallation CSA B149.
2.3 Installation of Outdoor Heaters
1. Locate the heater to provide the clearances as listed
in Table 1, “Minimum Heater Clearances.”
2. Do not place the heater in an enclosure or wall
recess. Avoid locations where wind defl ection off
structures might cause downdraft. When such wind
conditions are possible, place the heater at least 3
feet (0.9m) from the structures.
3. If the heater must be installed in a four sided
enclosure with an open top, such as when
equipment is surrounded by block walls, provision
for combustion air at the bottom of the enclosure
must be provided even if the enclosure is large.
Openings with a minimum of 1 square inch (6.5
sq. cm) per 4,000 BTU/hr input of all appliances
contained in the enclosure must be located in the
walls within 12” of the fl oor to provide enough
combustion air for the pool heater.
4. Never install the heater under any kind of roof
overhang. Do not place the heater below or adjacent
to any doors, windows, louvers, grills, etc., which
connect in any way with an inhabited area of a
building. This includes other structures such as
garages or utility rooms (see Figure 7).
5. Although these models are CSA design certifi ed
for outdoor installations, such installations are not
recommended in areas where the danger of freezing
exists unless proper precautions are taken for freeze
protection.
Outdoor installations are not recommended in areas
where the danger of snow blockage exists.
WARNING
Liquefi ed petroleum gas is heavier than air.
Therefore, the pool heater should not be
installed in pits or other locations where gas
could accumulate.
The heater should be located a safe distance from
Propane gas storage and fi lling equipment. Consult local
codes and fi re protection authorities for advice on specifi c
installation restrictions.
2.4 Gas Supply and Piping
Review the following instructions before proceeding with
the installation.
1. Verify that the heater is fi tted for the proper type of gas
by checking the rating plate. Laars heaters are normally
Heater Each Opening*
Size square inches square cm
500 125 806.5
600 150 967.8
715 179 1154.9
850 213 1374.3
1010 253 1632.4
1200 300 1935.6
1430 358 2309.8
1670 418 2696.9
1825 457 2948.6
Net Free Area.
*
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.
Area indicated is for one of two openings: one at fl oor level and
one at the ceiling, so the total net free area could be double the
fi gures indicated. For special conditions refer to the latest edition
of ANSI Z223.1.
Consult factory if openings do not communicate directly through
the walls with the outdoors.
Table 2 - Minimum Recommended Air Supply to Heater
Figure 7 - Incorrect Outdoor Installation
equipped to operate below a 2000 foot (609.6m)
altitude. Heaters equipped to operate at higher altitudes
have appropriate stickers or tags attached, also printed
information on rating plate.
2. Use the fi gures in Table 3 to provide adequate gas
piping from the gas meter to the heater.
3. A sediment trap (drip leg) must be provided ahead
of the gas controls (see Figure 8). A manual gas
shutoff valve must also be provided for service
convenience and safety. Check the local codes.
4. The heater 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 1/2 psig (3.5kPa). The heater
must be isolated from the gas supply piping system
by closing its individual manual gas shutoff valve
during any pressure testing of the piping system at
test pressures equal to or less than 1/2 psig (3.5kPa).
Page 8
LAARS Heating Systems
Distance from Gas Meter
Heater or Last Stage Regulator
Size
0-30.5m 30.5-61m 61-91.4m
500 1½" 2" 2"
600 1½" 2" 2½"
715 2" 2" 2½"
850 2" 2½" 2½"
1010 2" 2½" 3"
1200 2½" 3" 3"
1430 2½" 3" 3"
1670 2½" 3" 3
1825 2½" 3" 3½"
NOTE: These fi gures are for Natural Gas (.65 Sp. Gr.), and are
based on 1/2" water column pressure drop. Check supply pressure
with a manometer, and local code requirements for variations. For
Propane Gas, reduce pipe diameter one size. An average number
of tees and elbows have been taken into account.
Table 3 - Gas Piping Sizes
0-100' 100-200' 200-300'
5. Provide gas supply pressure to the heater as
follows:
Natural Gas Propane Gas
In. W.C. kPa In. W.C. kPa
Max. 10 2.5 13 3.4
Min. 6.5 1.6 11 2.7
NOTE: the heater and all other gas appliances sharing
the heater gas supply line must be fi ring at maximum
capacity to properly measure the inlet supply pressure.
Low gas pressure could be an indication of an undersized
gas meter and /or obstructed gas supply line.
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.
The gas manifold and control assembly is
factory tested and conforms to the safe lighting and other
performance criteria specifi ed in the latest editions of
ANSI Z21.13.CSA4.9, Low Pressure Boiler Standard.
Gas Supply
To
Equipment
Inlet
Nipple
Cap
Figure 8 - Sediment Trap Installation
Inlet
Te e
Fitting
3" (76mm) Min.
Before operating the heater, the complete gas supply
system and all connections must be tested for leaks using
a soap solution. Do not use raw fl ame.
Caution
Since some leak test solutions (including soap
and water) may cause corrosion or stress
cracking, the piping must be rinsed with water
after testing, unless it has been determined
that the leak test solution is noncorrosive.
2.5 Electrical Wiring
WARNING
The heater must be electrically grounded in
accordance with the most recent edition of
the National Electrical Code, ANSI/NFPA 70.
In Canada, all electrical wiring to the heater
should be in accordance with the latest edition
of CSA C22.1 Canadian Electrical Code, Part
1. Do not rely on the gas or water piping to
ground the metal parts of the heater. Plastic
pipe or dielectric unions often isolate the
heater electrically. Service and maintenance
personnel who work on or around the heater
may be standing on wet fl oors and could be
electrocuted by an ungrounded heater.
Wiring diagrams are included in the information packet
provided with each unit.
1. All Model AP pool heating heaters need 115V
60Hz supply voltage unless specifi cally ordered
otherwise.
2. The 1825 models are supplied with 3/4 HP pump
motors. All other models are supplied with 1/2 HP
pump motors. Consult the National Electrical Code
or the Canadian Electrical Code regarding branch
circuit requirements for equipment with these
motors.
3. The heaters should be wired exactly as shown in the
wiring diagram.
IMPORTANT NOTE: The pool fi lter pump and heater
must be electrically interlocked so the heater cannot
come on unless the pump is running and there is full
fl ow in the fi lter piping where the heater is connected. If
the pool fi lter pump operation is intermittent the heater
must be shut off prior to pump shutdown. See paragraph
heading Auxiliary Time Clock Wiring on the next page.
If the backwash operation is manual the heater must be
shut off manually during backwashing.
Mighty Therm Commercial Pool Heating Boiler
Figure 9 - Pressure Relief Valve Location
Auxiliary Time Clock Wiring:
If a time clock is used to control the fi lter pump
operation, a separate switch or relay must be used to
shut off the heater at least 15 minutes before the fi lter
pump is shut off. Wire the switch or relay (often called
the Fireman Switch) to the terminals shown in the wiring
diagram as “Field Interlock.”
4. All fi eld installed electrical safety devices and all
fi eld installed controllers (valve end switches, draft
switches, relays, timers) can be connected to the
heater control to the terminals shown in the wiring
diagram designated “Field Interlock.”
5. Field location of the temperature sensor is
described in Section 2.8.
Where the heater is installed with a draft fan refer to
the fan manufacturer's wiring diagram. The draft switch
should be wired across the fi eld interlock terminals in the
heater control panel.
Page 9
The pressure relief valve lever must be tripped at least
once a year to ensure that waterways are clean. When
manually operating lever, water will discharge through
the drain line. Precautions must be taken to avoid contact
with hot water and water damage.
2.7 Heater By-Pass Piping
All AP series heaters, 500-1825 models, must be installed
with bypass piping. Please use Figure 10 as your guide to
plumb the bypass. For spas see Section 3.9.
All models are supplied with integral pumps. These
pumps are sized for the pressure drop through the heat
exchanger, 30' of piping, and through the bypass piping
as shown in Figure 10.
If the distance from the pool heater to the pool loop
piping is greater than 15' please contact the Service
Department for assistance (see back page for phone and
fax numbers).
Any deviations from the arrangement shown may reduce
fl ow, hinder performance, and will void the warranty.
2½ inch NPT piping is shown, however, models 500I1430I and models 500E-1010E may be installed using 2
inch NPT piping.
All models must be installed in the primary/secondary
arrangement shown. The heater loop piping must tee into the
fi lter loop piping with the inlet and outlet connection spaced
a maximum of 4 pipe diameters apart (see Figure 10).
The integral pump will provide the right amount of fl ow
for the pool heater, and the return water to the pool will
be maintained below 104°F, provided the piping diagram
is followed correctly and the fi lter pump fl ow rate is at
least the “Minimum Filter Pump Flow Rate” in Table 4.
The outlet valve “B” and the bypass valve “A” must have
a provision for locking the handles in place (or removing
them) after the temperature rise and inlet temperature
adjustments have been made.
2.6 General Piping Instructions
In addition to the bypass valve “A” and outlet valve
“B” shown in Figure 10, an inlet valve “C” should be
provided so that the heater can be readily isolated for
service. Butterfl y and globe valves are recommended for
this application to allow for precise adjustment of water
fl ows. For spa applications see Section 3.9.
Since heater outlet temperatures can reach 150°F (66°C)
in some cases, copper or CPVC are recommended
materials for heater connection piping. PVC material may
be used for the inlet valve and the piping upstream of it.
When pipe, fi ttings, grids or any other element of the
fi lter system are made of plastic materials, they may be
damaged by the momentary "back siphoning" of hot
water from the heater when the fi lter pump stops running.
The pressure relief valve installed in the tapped opening
provided in the outlet header (see Figure 9), must be
piped, but not connected, to a drain or fl oor sink. The
drain pipe must be the same size as the valve outlet and
must pitch downward from the valve. Where no special
setting of the relief valve is ordered, the factory will
furnish a 75 psi setting.
Heater Model Minimum Filter Pump Flow Rate
500-850 90 GPM
1010-1200 110 GPM
1430 140 GPM
1670-1825 180 GPM
Table 4 - Minimum Flow to Supply Heater Loop
2.8 Temperature Sensor Placement
and Installation
Two temperature sensing devices are installed on the
heater that require sensing bulbs be fi eld installed
according to Figure 10.
1. Install the thermistor based sensor's immersion
well on the underside of the pool loop piping. The
well should be installed just upstream of the heater
inlet tee. DO NOT INSTALL the bulb in the
heater loop piping or down stream of the heater
outlet tee.
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