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

at the

outlet of the unit. The CO

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.

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

or O

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

in the “as installed” condition. Adjust the air shutter(s)

so that the CO

is about 8% or the O

is about 6.8% for

appliances operating on Natural Gas. For appliances

operating on LP Gas adjust the air shutter(s) so that the

is about 9.2% or the O

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

or O

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

or O

must be reset. CO

or O

will have changed when the manifold pressure was

adjusted. Open the air shutter(s) to reduce the CO

or O

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