LAARS Mighty Therm LO-NOx PW (Sizes 500-1825) - Install and Operating Manual - Manual (Page 23)

Mighty Therm Lo-NOx Page 23
6.3 Mechanical Components
6.3.1 Pressure Relief Valves Leaking Intermittently or Steadily
Possible Cause Remedy
A. Static pressure in system exceeds A. Calculate height of water in system above heater. Install
setting of relief valve. new valve with psi setting 25% above required static system
working pressure. Do not exceed 160 psi.
B. Expansion tank is waterlogged B. Drain expansion tank, then reopen it to the system. Look
(if installed). for leaks in expansion tank or fittings. Calculate required
volume of expansion tank in relation to system to
determine that tank is adequate.
6.3.2 Heater is Pounding, Knocking or Emitting Steam from Relief Valves
A. Low or no water flow. A. This condition is usually caused by lack of adequate water
flow through heater. Check the following:
1. Is the heater wired into the pump circuit so that the heater
cannot fire unless the pump is running?
2. Check to see that all valves in system are open to be sure
that water can circulate through the heater and the system.
3. If the system has automatic water valves (2-way or 3-way)
that can cut off the water flow through the heater, check to
see that they are equipped with end-switches which shut the
heater down when the water flow through the heater is
reduced by 70% from full flow
4. Examine pump for clogged impeller.
B. Low or no system pressure. B. Clean strainer in pressure reducing valve. Look for closed
valve water line or a leak in the system.
C. Clogged “Y” strainer. C. Remove strainer element and clean screen.
D. Debris from system piping is D. Remove header covers. Examine all tubes and waterways.
blocking tubes. Use new gaskets when reassembling. Clean out tubes.
E. Scale has formed in tubes. E. PH - Check for inflow of raw water (is due to system leak).
See Section 3.2.
PW - Water chemistry or flow problems, see Section 3.3.
6.3.3 Soot in Flueways or in Tubes, or Noxious Fumes Indicative of Bad Combustion
A. Combustion air supply to heater A. Check air supply opening. Look for debris in screen or
room is inadequate. louvre which covers combustion air opening, or for
material blocking the opening.
B. Stack or vent is blocked or restrictive. B. Look for blocked stack and excessive number of elbows in
stack or excessive length of horizontal runs.
C. Severe down draft is causing spillage C. Check for (1) proper vent cap on stack; (2) adequate height
of flue products into room. of stack above roof; (3) equipment exhausting air from
inside of building; and (4) proper installation of draft diverter.
D. Gas pressure to burners is excessive. D. Check gas pressure with manometer, and adjust with
heater firing at full rate.
E. Heater not fitted for the fuel being E. See nameplate for correct fuel.
supplied.
6.3.4 Water Dripping in Firebox
A. Tube in heat exchanger has A. A tube failure is almost always caused by (a) scale
overheated and ruptured. formation in the tube or (b) inadequate water flow through
the boiler.