LAARS Mighty Therm2 MT2V (Sizes 500–2000 MBTU/h) - Install and Operating Manual - Manual (Page 29)

Mighty Therm 2
Page 29
This step to be performed by a qualified service
person.
6.8 To Restart the Mighty Therm2
If drained, follow Section 6.2 in this manual for
proper filling and purging.
1. Switch off the main electrical disconnect switch.
2. Close all manual gas valves.
3. WAIT FIVE (5) MINUTES.
4. Set the aquastat or thermostat to its lowest setting.
5. Open all manual gas valves.
6. Reset all safety switches (pressure switch, manual
reset high limit, etc.).
7. Set the temperature controller to the desired
temperature setting and switch on electrical power.
8. Burner will go through a prepurge period and
ignitor warm-up period, followed by ignition.
SECTION 7.
Maintenance
7.1 System Maintenance
1. Lubricate the system water-circulating pump, if
required, per the instructions on the pump.
2. If a strainer is employed in a pressure reducing
valve or the piping, clean it every six months.
3. Inspect the venting system for obstruction or
leakage at least once a year. Periodically clean the
screens in the vent terminal and combustion air
terminal (when used).
4. Keep the appliance area clear and free from
combustible materials, gasoline, and other
flammable vapors and liquids.
5. If the appliance is not going to be used for
extended periods in locations where freezing
normally occurs, it should be isolated from the
system and completely drained of all water. All
systems connected to it should also be drained or
protected from freezing.
6. Low water cutoffs, if installed, should be checked
every 6 months. Float type low water cutoff should
be flushed periodically.
7. Inspect flue passages, and clean with brushes/
vacuums, if necessary. Sooting in flue passages
indicates improper combustion. Determine the
cause and correct.
8. Inspect the vent system and air intake system,
and if the vent system is Category III, ensure that
all joints are sealed properly. If joints need to
be resealed, completely remove existing sealing
material, and clean with alcohol. Apply new sealing
material, and re-assemble.
7.2 Appliance Maintenance and Component
Description
No orifice changes are required to adjust the
Mighty Therm2 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 and replaced
after the adjustments have been completed and the
fitting, hose and manometer have been removed and the
1/8" plug has been replaced. 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 from the staging control.
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
kPa) and the CO
2
is adjusted to 8.0% for Natural Gas
appliances or 9.2% for LP appliances (to be checked
only at full fire). When using an O
2
analyzer, the correct
O
2
is 6.8% for both Natural Gas and LP appliances.
Caution
Should any odor of gas be detected, or if the gas
burner does not appear to be functioning in a normal
manner, close main shutoff valve, do not shut off
switch, and contact your heating contractor, gas
company, or factory representative.
6.7 Shutting Down the Mighty Therm2
1. Switch off the main electrical disconnect switch.
2. Close all manual gas valves.
3. If freezing is anticipated, drain the Mighty Therm2
and be sure to also protect building piping from
freezing.