Operating instructions

Mighty Therm2
Page 27
unit to light. While the unit is operating, close the
manual gas valve and ensure that power to the main
gas valve has been cut.
16. Within three (3) days of start-up, recheck all air
bleeders and the expansion tank as described in
Steps 4 and 8 above.
Important: The installer is responsible for identifying to
the owner/operator the location of all emergency shutoff
devices.
WARNING
Do not use this appliance if any part has been under
water. Immediately call a qualied service technician
to inspect the appliance
and to replace any part of the control system and any
gas control that may have been
under water.
6.3 Operating Temperature Control
All Mighty Therm2's are equipped with a two-stage
aquastat. To utilize this mounted controller be sure to
have the "Local/Remote" selector switch to "Local".
Set the controller to the desired operating set point.
The controller has an interstage differential that can be
adjusted from 3°F to 10°F. This allows the user to have
some control over how stage 2 and stage 1 call for heat
(see Figure 22).
Because the Mighty Therm2 controller senses inlet
6.2 Filling the System
1. Ensure the system is fully connected. Close all
bleeding devices and open make-up water valve.
Allow system to ll slowly.
2. If make-up water pump is employed, adjust
pressure switch on pumping system to provide a
minimum of 12 psi (81.8 kPa) at the highest point
in the heating loop.
3. If a water pressure regulator is provided on the
make-up water line, adjust the pressure regulator
to provide at least 12 psi (81.8 kPa) at the highest
point in the heating loop.
4. Open bleeding devices on all radiation units at the
high points in the piping throughout the system,
unless automatic air bleeders are provided at such
points.
5. Run system circulating pump for a minimum of 30
minutes with the boiler shut off.
6. Open all strainers in the circulating system, check
ow switch operation, and check for debris. If
debris is present, clean out to ensure proper circula-
tion.
7. Recheck all air bleeders as described in Step 4.
8. Check liquid level in expansion tank. With the
system full of water and under normal operating
pressure, the level of water in the expansion tank
should not exceed ¼ of the total, with the balance
lled with air.
9. Start up system according to the procedure in this
manual. Operate the entire system, including the
pump, boiler, and radiation units for one (1) hour.
10. Recheck the water level in the expansion tank. If
the water level exceeds ¼ of the volume of the
expansion tank, open the tank drain, and drain to
that level.
11. Shut down the entire system and vent all radiation
units and high points in the system piping, as
described in Step 4.
12. Close make-up water valve and check strainer in
pressure reducing valve for sediment or debris from
the make-up water line. Reopen make-up water
valve.
13. Check gauge for correct water pressure and also
check water level in the system. If the height
indicated above the boiler insures that water is at
the highest point in the circulating loop, then the
system is ready for operation.
14. Refer to local codes and the make-up water valve
manufacturer’s instructions as to whether the
make-up water valve should be left open or closed.
15. After placing the unit in operation, the ignition
system safety shutoff device must be tested. First,
shut off the manual gas valve, and call the unit
for heat. After the pre-purge and ignitor heat-up
time, the main gas terminals will be energized,
attempting to light, for four (4) seconds, and then
will de-energize. The unit will go into lockout
mode. Second, turn the power off and then on
again, open the manual gas valve and allow the
*1 Difference between the temperatures at which the two switch-
es make R-W. Adjustable from 3°F to 10°F (1.7°C to 5.6°C) on
standard models, or from 3.6°F to 12°F (2.0°C to 6.7°C); 55°F to
175°F (13°C to 79°C) models.
*2 Two DPDT switches operate in sequence. Each switch differ-
ential is xed at approximately 3°F (1.7°C) on standard models, or
3.6°F (2.0°C); 55°F to 175°F (13°C to 79°C) models.
Figure 22. Honeywell L8008G.