LAARS Mighty Therm2 MT2V (Sizes 500–2000 MBTU/h) - Install and Operating Manual - Manual (Page 31)

Mighty Therm 2
Page 31
7.2.8 Transformer
The transformer is not capable of supplying control
voltage for external devices such as zone valves, which
must have their own separate power supply. Should a
transformer need replacing, shut off the 120-volt power.
Unplug the transformer wires, remove the mounting
screws and remove the transformer. Replace transformer
in the reverse order.
7.2.9 Blowers
The combustion air blowers bring the combustion
air for the Mighty Therm2 from the upper chamber to
the lower chamber. Mixing of the gas and air occurs
in the burners. Sizes 500, 750 and 1000 each have one
blower, and sizes 1250 to 2000 each have two blowers.
If a blower change is required, turn off the 120-volt
power and gas supply to the unit. Remove the front
panel. Disconnect the blower's wire harness. Remove
the screws at the blower flange, and pull the blower out.
Replace blower in reverse order, ensuring that all joints
are made correctly. After replacement, ensure that the
unit operates properly, by following the set-up procedure
in this manual.
7.2.10 Flow Switch
The Mighty Therm2 uses a paddle-type flow switch
to ensure that the unit has water flow before ignition is
allowed.
7.2.11 Heat Exchanger Coil
WARNING
Black carbon soot buildup on a dirty heat exchanger
can be ignited by a random spark or flame, thereby
creating a risk of fire or explosion.. To prevent this
from happening, dampen the soot deposits with a wet
brush or fine water spray before servicing the heat
exchanger.
The Mighty Therm2 has a pre-mixed burner
system. These systems provide the burners with
sufficient air for complete combustion, and black carbon
sooting is seldom experienced. If sooting is suspected,
view ports for inspection of the heat exchanger are
provided on the right side of the boiler. They are located
below the headers, and are accessed by opening the
small round cover that is attached by one screw. In the
unlikely event that there is a buildup of black carbon
soot or other debris on the heat exchanger, clean per the
following:
1. Disconnect the electrical supply to the unit.
2. Turn off the gas supply by closing the manual gas
valve on the heater.
3. Disconnect and remove the wires, conduit and
sensors from all components that are attached to
the inlet/outlet header.
4. Isolate the heat exchanger from the water supply.
5. Disconnect the header flanges from the inlet and
outlet.
6. Allow the heat exchanger to drain. Remove the
front cover(s) by removing the rubber access
strip(s) and the retaining screws. Remove the
venting and remove the top, by removing the
screws that attach the top to the side panels.
Remove the side panels. Remove the front lower
panels sealing the combustion area. To remove
the gas train, disconnect the unions located below
the intermediate pan and the field installed union
located outside the cabinet, and pull up, bringing
the union end connectors through the grommets in
the intermediate pan. To remove the intermediate
pan, remove the slide out control assembly and
blower(s) to reveal the screws. Remove the screws
holding the intermediate pan, and lift up to remove
it. The heat exchanger has integral metal sections
attached, which connect to the frame of the boiler.
Locate and remove the screws along the front,
rear and bottom of the integral metal sections, and
remove the heat exchanger and metal sections by
lifting up. On the larger appliances, a center heat
exchanger support must be unbolted before it can
be removed.
7. Remove the heat exchanger from the unit. Note:
The heat exchangers are heavy and may require
two people to remove to avoid personal injury.
8. Clean the heat exchanger: A light accumulation of
soot or corrosion on the outside of the heat ex-
changer can be easily removed. Use a wire brush to
remove loose soot and scale from the heat exchang-
er. Do not use water or compressed air for cleaning.
9. Note: While the heat exchanger is out of the unit,
inspect the firewall refractory insulation. Replace if
necessary.
10. Inspect the inside of the copper tubes for scale
buildup. Scale can build up on the inner surface of
the heat exchanger tubes, which can restrict water
flow. If the tubes show signs of scaling, clean the
internal surface. Laars offers a tube cleaning kit,
part number R0010000.
11. Reassemble in the reverse order, and check
appliance operation after start-up.
NOTE: The Warranty does not cover damage caused
by lack of required maintenance, lack of water flow,
or improper operating practices.