|
Gas Furnace Probs - HELP!
QUESTION:Our gas furnace has a major problem which has been unsuccessfully
"fixed" 3 times. If the thermostat is turned up, the furnace will come
on, will give off heat and will then abruptly turn off after 3-5 minutes.
It will not come back on again unless the circuit is turned off and then
back on again at the thermostat. The thermostat has been replaced twice,
which I never really thought was the problem, since obviously the
connection is ok as it will turn the furnace on. The other "repair" was
to merely clean out the furnace grates and accessible furnace parts of
dust and cobwebs. oh, the furnace is located in the crawl space under the
house.
If anyone has seen this problem and a solution before, please let me
know!
Also, if you know of any good furnace repair people in the bay area
(penninsula).
ANSWER: You didn't say what kind of fuel your furnace is using. I assume in CA
its natural gas. You need first to figure out what kind of thermostat
your furnace uses. One kind operates on 24v and utilizes a transformer
to provide the 24v current. The other, called a millivolt thermostat,
uses a thermocouple heated by the pilot light to provide a very low
voltage (under 1v) and does not have a transformer. Three
possibilities come to mind. One is a loose or weak connection in the
thermostat circuit between the thermostat and gas control valve. You
might just check all the connections you can find - be sure the screws
are tight and the wires not corroded or partially broken. Another is a
sticky gas control valve. This would require professional replacement.
The millivolt system is VERY sensitive to bad connections, and might
also have a weak thermocouple. The thermocouple is easily replaced, and
since it does not require opening the gas piping is something you might
consider trying yourselves. (Do not confuse a millivolt thermocouple
with the safety thermocouple for the pilot light) This type of
thermostat system is commonly found in floor furnaces and wall furnaces
that do not have electric power for a blower.
|
|
|
|
