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Williams gas furnace lemon
QUESTION:A friend of mine has a problem with a Williams gas wall furnace. It has been
"repaired" by "professionals" three times in 18 months, each time costing
$50-75. Even the rep from the gas supplier does not know what the problem
is. After repairs, the furnace will run for a couple of weeks and then
refuse to light. The pilot light assembly was taken apart, cleaned, and
reinstalled and it lights ok but, when the knob is released and then turned
to the run position, there is no flame. The sensor that the pilot flame
plays on was also cleaned.
The gas valve control is made by ITT General controls and has 4
electrical connections. Two of these are contacts for wires that
come from the sensor sticking into the pilot flame and from a second
sensor that is at the top of the heater. I suspect that this one is
an overheating cut-out and it has two relatively heavy cables. That
sensor is circular, about 0.5" diameter and about 1/4" deep.
Anyone know anything about the characteristics of this unit, or of
the flame sensor? I could check outputs with a voltmeter or check
resistances. I haven't checked yet, but I would think that the
other connections are for two wires from the thermostat. If they are,
shorting these out should simulate a thermostat fully on?
This seems bizarre behavior. I lived in apartments for many years that had
the same kind of heaters and they never gave a problem, but then Williams
probably didn't make them. I have read numerous accounts of problems with
this brand, so it appears to be a lemon. Any comments on the economics of
buying the whole control unit or buying a new heater. Most likely the
problem is with some of the controls. The flame sensor has been replaced
several times and costs about $28. This furnace has an output of 25,000
BTU/hr and has no fan. Anyone know of good reliable brand heaters? Any
on-line sources for these?
ANSWER: I went thought the same thing you did with the Williams. After replacing
the thermocouple two times within 1 year I finally realized the ITT valve box is
really ty as you described as
it doesn't failed completely. Williams replaced this ITT with a different valve
box but it a pain to install.
There are a few things you could check:
be sure the new thermocouple is all the way up above the flame.
the temperature safety switch is normally closed. that is, 0 ohms across the
terminals 2-3. remove one wire from terminal strip to check. replace if
defective.
the thermostat contacts is closed for heat and open for none on terminals 1-3.
remove one wire from terminal strip to check.
To test out valve box:
short terminals 2-3, temperature limit switch; and short terminals 1-3,
thermostat.
if it doesn't fire up, its either the thermocouple or the valve box.
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