Furnace will not turn off

Old 10-12-02, 08:08 AM
lynn shepley
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Furnace will not turn off

I have a forced hot air heating system. The furnace is a natural gas fired model.

The problem is I can't turn the furnace off at the thermostat. I have to switch it off at the circuit breaker. I replaced the thermostat with an identical replacement and the problem still persists. What should I do now?
Old 10-12-02, 11:50 AM
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Location: Deer Park, N.Y.
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Unhappy same problem here

hi, sorry i dont have the answer to your problem, i instead have the same problem!!!
i came here looking for help too, i think i will call a heating store and see what they tell me, at least they wont be looking for a fee//$$$
i had a company replace the thermocouple and gas line yesterday and after he left i turned off the thermostat and later realized the stupid thing is still on too!!!
if i get any credible answers i'll let you know..

mike in new york
Old 10-12-02, 12:16 PM
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Ouch. Sounds to me like you've both got a control problem. There should be a control board in the furnace that controls the fan, gas valve and the like. While the t-stat is cutting off the 24 volt control voltage and thus thinking its turning off the furnace, the board may have failed in that it does not open the curcuit. This would keep the unit running all the time.

A volt meter and the ability to read a wiring diagram would help check this out.
Old 10-13-02, 10:03 AM
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Furnace Problems

Hello lynn shepley & michael4244.

You both indeed may have the same, different or similar problem. The question is in referrance to what you each mean by can't turn the furnace off.

Turning of the burners? Or is it turning off the fan?

If the burners fail to turn off, disconnect the wires either at the gas control valve or at the thermostat. Doing so should turn off the burners, if indeed the burners are remaining.

If the fan fails to turn off after several minutes of coolling down time and the burners have turned off, the fan relay {fan switch} may be the cause of the problem.

If the turning off the burners is the problem and is corrected by disconnecting the thermostat, check the wiring for the problem. If turning off the fan is the problem, check the fan relay switch.

Be advised that fan switches, also commonly referred to as fan replys and other terms, are high voltage parts. They operate on house current.

The furnace must be turned off at the power source prior to attempting any tests, checks or part removals to prevent shocks or electrocution!

Additional Suggestions:
Read the manufacturers online web site for product information, problem possibilities, causes and solving methods, part locations, disassembly, reassembly methods, repair procedures and instructions, pictorials and schematics, all or part of which may be available online.

An excellent source for orginal replacement parts is your local retail appliance parts store. Appliance parts dealers test and carry replacement parts for all appliances. Parts dealers are listed in the phone book under appliances.

Retail parts dealers can also help determine what the possible problem may be. Bring the make, model and serial numbers if you stop in at the store. The info will help to determine the ignition system and possible problem causes.

Several other resident heating and cooling professionals on this type of heating system, replying within this forum, could have additional helpful information, suggestions, advice. Check back on your question several times for additional replies.

Read the RECENT postings within this forum, for other postings on this subject and the replies offered.

If you need further assistance, use the REPLY button to add any additional information or questions. Using this method also moves the topic back up to the top of the list automatically.

Regards & Good Luck, Forum Host & Moderator.
TCB4U2B2B Company Enterprises. Energy Conservation Consultants & Gas Appliance Diagnostics Technicians.
Old 10-13-02, 01:51 PM
Join Date: Jun 2001
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hi again, i solved my problem on my own, although i traced the problem back to something i did before i called the service man to my home.

i removed the thermocouple and the pilot line while i brainstormed the problem and i noticed a small tube with a small hole fall to the ground.
knowing this came from the gas line orifice i somehow forgot to replace it and when i had my pilot valve put on i noticed a rather large flame, like 10-12 inches. so i new this wasnt helping my problem.
then i also found that when i tried to lower the pilot on the pilot control valve that didnt do the trick either.

so finally i remembered that i did not replace that stupid tube, and so i took everything apart and put it back and wala!!!!

everything works...

all i can say is check if you valve pilot is too big, or simply change the orifice anyway, its cheap to do so

good luck.

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