LAARS Mighty Therm2 MT2P (Sizes 500–2000 MBTU/h) - Install and Operating Manual - Manual (Page 19)

MT2P Pool Heater Page 19
6.3 Operating the Burner and Set Up
6.3.1 Set Up for 0 to 2500 Feet Altitude
The setup must be checked before the unit is put
in operation. Problems such as failure to start, rough
ignition, strong exhaust odors, etc. can be due to
improper setup. Damage to the heater resulting from
improper setup is not covered by the limited warranty.
1. Using this manual, make sure the installation
is complete and fully in compliance with the
instructions.
2. Determine that the appliance and system are filled
with water and all air has been bled from both.
Open all valves.
3. Observe all warnings on the Operating
Instructions label and turn on gas and electrical
power to appliance.
4. Switch on the appliance power switch located on
the right side of the unit.
5. The MT2P will enter the start sequence, as long
as the unit is being called for heat. The blower
and pump come on for pre-purge, then the ignitor
warm-up sequence starts and after the ignitor
warm-up is complete and all safety devices are
verified, the gas valves open. If ignition doesn’t
occur, check that there is proper gas supply. Wait
5 minutes and start the unit again. During initial
start up, air in the gas line may cause the MT2P to
"lock out" during the first few trials for ignition.
Depending on the ignition modules installed, the
manual reset button on the ignition module(s) may
need to be depressed to restart the heater.
6. When the unit is running, the supply gas pressure
must be checked. Inlet gas pressure must not
exceed 13" W.C. (3.2kPa). The minimum inlet gas
pressure is 5" W.C. (1.2kPa).
7. Once the inlet gas pressure is verified, the
outlet gas pressure from each valve (manifold
gas pressure) must be checked, and adjusted, if
necessary. The manifold gas pressure must be 2.5"
W.C. (0.62kPa).
8. Complete the setup by checking the CO
2
at the
outlet of the unit. The CO
2
should be 8% for
natural gas, or 9.2% for propane.
9. After placing the appliance in operation, the
Burner Safety Shutoff Device must be tested.
To test:
(a) Close gas shutoff valve with burner
operating.
(b) The flame will go out and blower will
continue to run for the post purge cycle.
Three (3) additional attempts to light will
follow (only one (1) attempt for optional
module). Ignition will not occur as the gas
is off. The ignition control will lockout, and
will have to be reset before the unit will
operate. The ignition control reset button is
located on each ignition control, in the lower
right corner, and can be reset by depressing.
It is not marked on the ignition control label.
(c) Open gas shutoff valve. Restart the
appliance. The ignition sequence will start
again and the burner will start. The appliance
will return to its previous mode of operation.
NOTE: Models 1250, 1500, 1750 and 2000 have two
ignition controls and two ignitors.
6.3.2 High Altitude Adjustment and Set Up
MT2P appliances may be operated at high
altitude (7700 ft., 2347 m) with a reduction in output
of approximately 10%. At elevations higher than 7700
ft. (2347 m) the reduction in output will exceed 10%
and at elevations below 7700 ft. (2347 m) it will be
less than 10%. When adjusted properly, the appliance
will perform properly at any altitude. High altitude
adjustment must not be made on appliances operating at
elevations below 2500 ft. (762 m).
No orifice changes are required to adjust the
MT2P appliances for high altitude. High altitude
adjustment is accomplished by adjustment of the gas
valve manifold pressure and the air shutter(s). The
required instruments used to assist in these adjustments
are a CO
2
or O
2
Analyzer and a U-Tube Manometer or
other device capable of reading a pressure of 2.5-3.0
inches W.C. (0.62-0.75 kPa).
Start the adjustment process by checking the CO
2
in the “as installed” condition. Adjust the air shutter(s)
so that the CO
2
is about 8% or the O
2
is about 6.8% for
appliances operating on Natural Gas. For appliances
operating on LP Gas adjust the air shutter(s) so that the
CO
2
is about 9.2% or the O
2
is about 6.8%. Appliances
with two blowers should be adjusted so that the air
shutters below each blower are open the same amount.
Once the CO
2
or O
2
has been set, the manifold
pressure may be adjusted. Remove the 1/8 NPT plug
from the lower side of the gas valve that is to be set
and install a fitting, hose and manometer. Start the
appliance and observe the manifold pressure. Manifold
pressure must be adjusted to 3.0 in. w.c. (0.75 kPa) (for
high altitude only, standard operating pressure is 2.5 in.
w.c. (0.62 kPa)). It is adjusted by removing the slotted
cap on the gas valve and turning the adjustment screw
(beneath the cap) clockwise to increase pressure . After
the adjustments have been completed, the fitting, hose
and manometer have been removed and the 1/8" plug
has been replaced, replace the cap. Repeat this process
until all gas valves have been set. Note: The pressure
can be set only when the appliance is operating and
only when the particular gas valve being adjusted is
energized by a call for heat.
After all of the gas valve manifold pressures
have been set, the CO
2
or O
2
must be reset. CO
2
or O
2
will have changed when the manifold pressure was
adjusted. Open the air shutter(s) to reduce the CO
2
or O
2
to the values achieved previously.
The procedure is complete when all gas valves
are adjusted to a manifold pressure of 3.0 in. w.c. (0.75