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II. HEATER IS POUNDING, KNOCKING OR EMIT-
TING STEAM FROM RELIEF VALVES.
Possible Cause
A. Low or no water flow.
B. Low or no system pressure.
C. Clogged "Y" strainer.
D. Debris from system piping
is blocking tubes.
E. Scale has formed in tubes.
III. WATER DRIPPING
IN FIREBOX.
Possible Cause
Tube in heat exchanger has
overheated and ruptured.
What To Do
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. Clean strainer in pressure
reducing valve. Look for closed
valve water line or a leak in the
system.
C. Remove strainer element and
clean screen.
D. Remove header covers.
Examine all tubes and
waterways. Use new gaskets
when reassembling. Clean
out 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.
What To Do
A tube failure is almost always
caused by (a) scale formation
in the tube or (b) inadequate
water flow through the heater.
IV. PRESSURE RELIEF VALVES LEAKING INTER-
MITTENTLY OR STEADILY.
Possible Cause
A.Static pressure in system
exceeds setting of relief valve.
B. Expansion tank is water-
logged (if installed).
V. SOOT IN FLUEWAYS OR IN TUBES, OR NOX-
IOUS FUMES INDICATIVE OF BAD COMBUSTION.
Possible Cause
A. Combustion air supply to
heater room is inadequate.
B. Stack or vent is blocked or
restrictive.
C.Severe down draft is causing
spillage of flue products into
room.
D.Gas pressure to burners is
excessive.
E. Heater not fitted for the fuel
supplied.
F. Heater installed at high
altitude without proper
derating.
BRADFORD WHITE
What To Do
A. Calculate height of water in
system above heater. Install
new valve with psi setting 25%
above required static system
working pressure. Do not
exceed 160 psi.
B. Drain expansion tank, then
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.
What To Do
A. Check air supply opening.
Look for debris in screen or
louvre which covers combus-
tion air opening, or for material
blocking the opening.
B. Look for blocked stack and
excessive number of elbows in
stack or excessive length of
horizontal runs.
C.Check for (1) proper vent cap
on stack; (2) adequate height
of stack above roof;
(3) equipment exhausting air
from inside of building; and
(4) proper installation of draft
diverter.
D.Check gas pressure with
nanometer, and adjust with
heater firing at full rate.
E. See nameplate for correct fuel.
F. Installations at altitudes in
excess of 2000 ft. above sea
level are subject to jurisdiction
of the local inspection
authorities.
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