LAARS Mighty Therm HH-PH (Sizes 175-400) - Installation, Operation and Maintenance Instructions - Manual (Page 11)

Mighty Therm HH-PH Hydronic Boilers Page 11
21. Install the sensing bulb(s) into the appropriate
thermowell (keep in mind that the positions of
the inlet and outlet have been reversed. The inlet
is now behind the outlet).
22. Fasten the capillary tube(s) by squeezing the
retaining clip together, then tighten the screw.
23. Feed the two brown wires through the top hole
on the left side until the conduit elbow is against
the jacket.
24. Fasten the conduit by sliding the retaining nut
over the two brown wires (inside the control
compartment) then screwing it down finger-tight
on the conduit elbow.
25. Straighten the capillary tubing and fasten it to the
side of the boiler under the channel. Use the self-
tapping screws to fasten the channel to the
jacket.
26. Attach the two brown wires to terminals No. 5
and 6 on the terminal strip. Keep all wiring away
from surfaces that will get hot during boiler
operation.
27. Replace the gap closures and tighten the screws
securely.
28. Replace the three grommets and the cap.
29. Reinstall the drain plug and drain valves.
30. Slip the flue collector assembly back down
inside the enclosure.
31. Carefully slip a hand inside to make sure there
are no gaps between the heat exchanger and the
flue collector.
32. Check to make sure the wiring is not pinched
against sharp edges, or resting on the collector
assembly.
33. Replace the two flue collector hold down clamps.
34. Replace the top assembly and fasten it with the
hex-head screws.
35. Reinstall the vent cap or drafthood if one was
removed.
36. On indoor installations, plug the draft hood switch
into the receptacle on the left side of the boiler.
Temperature Rise in °F °C
20°F 11°C 25°F 14°C 30°F 17°C 35°F 19°C
Size GPM L/s H/L* GPM L/s H/L* GPM L/s H/L* GPM L/s H/L*
ft m ft m ft m ft m
175 14 0.88 1.0 0.3 11 0.69 0.6 0.2 9 0.57 0.5 0.2 8 0.50 0.3 0.1
250 20 1.26 2.1 0.6 16 1.00 1.2 0.4 13 0.82 0.8 0.2 11 0.69 0.6 0.2
325 25 1.58 3.4 1.0 20 1.26 2.1 0.6 17 1.07 1.4 0.4 15 0.94 1.1 0.3
400 31 1.96 5.2 1.6 25 1.58 3.4 1.0 21 1.32 2.3 0.7 18 1.13 1.7 0.5
Water Flow - GPM or L/s
*Pressure drop (head loss) through the boiler, expressed in feet or meters of water (H
2
0).
Table 3. Temperature Rise.
2F-2. Freeze Protection
Proper precautions for freeze protection are
recommended for boiler installations in areas where
the danger of freezing exists.
Power outage, interruption of gas supply, failure
of system components, activation of safety devices,
etc., may prevent a boiler from firing. Any time a
boiler is subjected to freezing conditions, and the
boiler is not able to fire, and/or the water is not
able to circulate, there is a risk of freezing in the
boiler or in the pipes in the system. When water
freezes, it expands. This can result in bursting of pipes
in the system, or damage to the boiler, which could
result in leaking or flooding conditions.
Do not use automotive anti-freeze. Maintaining a
mixture of minimum 50% water and maximum 50%
properly inhibited HVAC glycol, which contains an
antifoamant, is the preferred method of freeze
protection for Mighty Therm boilers. Percentage of
glycol used in the Mighty Therm boiler must not
exceed 50%. Typically, this mixture will serve as
burst protection for temperatures down to
approximately -35°F (-30°C). To get the desired
temperature rise across the boiler when the is mixture
is used, increase the water flow by 15% above the
original recommendation. Increase the head loss
requirement by 20%
IMPORTANT NOTES: Different glycol
products may provide varying degrees of protection.
Glycol products must be maintained properly in a
heating system, or they may become ineffective.
Consult the glycol specifications, or the glycol
manufacturer, for information about specific products,
maintenance of solutions, and set up according to your
particular conditions.
2F-3. Pump Requirements
High recovery, low volume water boilers need
enough water flow for efficient operation. The system
pump must develop enough pressure to overcome the
pressure drop of the boiler plus the pressure drop of
the entire circulation system at the flow rates selected
from Table 3.