Gas and Oil Home Heating Furnaces - Ignition problems with gas floor furnace
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11-07-00, 08:59 AM
I am having problems with ignition in my gas floor furnace. I have lived in this 60 year old house for 10 years and crawl under the house to light the furnace every year. However, I am now experiencing problems:
The system is self-generating; there are no external voltages applied to the controls. Just a two-wire thermostat on the wall and a thermopile underneath on the furnace pilot light. The two thermostat wires and the two thermopile wires all connect to three terminals on the control valve on the furnace.
There has never been a problem lighting the pilot, but the last couple years it has been harder to get the burners to ignite. Last year I replaced the thermostat with a LUX T10-1141 Thermostat.
This year, cleaning the wires and terminals at the control valve on the furnace did not help -- the thermostat on the wall would still not make the burners ignite; the only way I was able to get the burners to ignite was to short across the thermostat terminals at the control valve with a wire. I finally decided to let the burners burn for about 20 minutes, and then, after that, the thermostat would finally turn the burners on and off. It is working fine now, but I know I will have to go through the same thing next year, unless I find the root of the problem. What could be the problem?
Anthony
The system is self-generating; there are no external voltages applied to the controls. Just a two-wire thermostat on the wall and a thermopile underneath on the furnace pilot light. The two thermostat wires and the two thermopile wires all connect to three terminals on the control valve on the furnace.
There has never been a problem lighting the pilot, but the last couple years it has been harder to get the burners to ignite. Last year I replaced the thermostat with a LUX T10-1141 Thermostat.
This year, cleaning the wires and terminals at the control valve on the furnace did not help -- the thermostat on the wall would still not make the burners ignite; the only way I was able to get the burners to ignite was to short across the thermostat terminals at the control valve with a wire. I finally decided to let the burners burn for about 20 minutes, and then, after that, the thermostat would finally turn the burners on and off. It is working fine now, but I know I will have to go through the same thing next year, unless I find the root of the problem. What could be the problem?
Anthony
11-07-00, 01:43 PM
Hi Anthony:
You can only use a millvolt thermostat with a millivolt system. I'm not familiar with that particular Lux model, but you need to check the paperwork and see if it can be applied to a millivoltage system. Since jumping out the stat makes the furnace run ok, I think you need to change back to a millivolt thermostat such as a Honeywell. If you go to http://hbctechlit.honeywell.com/ and search for millivolt or thermopile, you'll find some appropriate model #'s. Thanks. John.
You can only use a millvolt thermostat with a millivolt system. I'm not familiar with that particular Lux model, but you need to check the paperwork and see if it can be applied to a millivoltage system. Since jumping out the stat makes the furnace run ok, I think you need to change back to a millivolt thermostat such as a Honeywell. If you go to http://hbctechlit.honeywell.com/ and search for millivolt or thermopile, you'll find some appropriate model #'s. Thanks. John.
11-07-00, 03:06 PM
John,
The Lux thermostat states that it can be used with a millivolt system or a 24V system.
Anthony
The Lux thermostat states that it can be used with a millivolt system or a 24V system.
Anthony
11-07-00, 09:11 PM
Hi:Anthony
The problem is most likely the pilot generator <thermopile?> is getting weak. As they deteriorate, with age, they produce less current.
Another possibility is the pilot flame may be too cold. Pilot generators produce current proportionially to how much heat they get. The tip must glow cherry red.
Be sure there isn't any dust in the pilot assembly and the flame is totally blue and sharp looking in contrast.
If the pilot flame is a soft weak looking blue or has any hint of yellow, the flame will be too cool to correctly heat the pilot generator.
<The correct name for the part I am referring to here is a pilot generator. I am assuming the thermopile mentioned here is the same part.>
Good Luck,
TomBartco
The problem is most likely the pilot generator <thermopile?> is getting weak. As they deteriorate, with age, they produce less current.
Another possibility is the pilot flame may be too cold. Pilot generators produce current proportionially to how much heat they get. The tip must glow cherry red.
Be sure there isn't any dust in the pilot assembly and the flame is totally blue and sharp looking in contrast.
If the pilot flame is a soft weak looking blue or has any hint of yellow, the flame will be too cool to correctly heat the pilot generator.
<The correct name for the part I am referring to here is a pilot generator. I am assuming the thermopile mentioned here is the same part.>
Good Luck,
TomBartco