LAARS Mighty Therm IW (Sizes 500-1825) - Installation, Operation and Maintenance Instructions - Manual (Page 21)

Mighty Therm Volume Water Heater
Page 21
II. HEATER IS POUNDING, KNOCKING OR
EMITTING STEAM FROM RELIEF VALVES.
Possible Cause What To Do
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 D. Remove header covers.
is blocking tubes. Examine all tubes and
waterways. Use new gaskets
when reassembling. Clean
out tubes.
E. Scale has formed in tubes. E. This is always caused by the
inflow of raw water into the
system. Clean tubes with tube
cleaning kit. Determine
hardness. Check water flow,
replace pump for modified
flow if necessary.
IV. PRESSURE RELIEF VALVES LEAKING
INTERMITTENTLY OR STEADILY.
Possible Cause What To Do
A.Static pressure in system A. Calculate height of water in
exceeds setting of relief valve. system above heater. Install
new valve with psi setting 25%
above required static system
working pressure. Do not
exceed 160 psi.
B. Expansion tank is water- B. Drain expansion tank, then
logged (if installed). reopen it to the system. Look
for leaks in expansion tank or
fittings. Calculate required
volume of expansion tank in
relation to system to determine
if tank is adequate.
V. SOOT IN FLUEWAYS OR IN TUBES, OR
NOXIOUS FUMES INDICATIVE OF BAD
COMBUSTION.
Possible Cause What To Do
A. Combustion air supply to A. Check air supply opening.
heater room is inadequate. Look for debris in screen or
louvre which covers
combustion air opening, or for
material blocking the opening.
B. Stack or vent is blocked or B. Look for blocked stack and
restrictive. excessive number of elbows in
stack or excessive length of
horizontal runs.
C.Severe down draft is causing C.Check for (1) proper vent cap
spillage of flue products into on stack; (2) adequate height
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 D.Check gas pressure with
excessive. nanometer, and adjust with
heater firing at full rate.
E. Heater not fitted for the fuel E. See nameplate for correct fuel.
supplied.
F. Heater installed at high F. Installations at altitudes in
altitude without proper excess of 2000 ft. above sea
derating. level are subject to jurisdiction
of the local inspection
authorities.
III. WATER DRIPPING
IN FIREBOX.
Possible Cause What To Do
Tube in heat exchanger has A tube failure is almost always
overheated and ruptured. caused by (a) scale formation
in the tube or (b) inadequate
water flow through the boiler.