Gas and Oil Home Heating Furnaces - help!
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12-21-01, 04:58 PM
I have a gas furnace, and it started acting up last winter.. what it does is it will kick on and run fine, but then most of the time, it kicks on, goes out and continuously does this.. What it does when it runs, is that it kicks on (the gas), then something else will kick on (the blower I guess) and the heat will come thru the vent.. but what it is doing, is it will kick on, then go (swish) out, then try to kick back on, etc.. we are freezing to death here.. its supposed to get down to 15 tonight. Please help me , I have 2 young daughters.. I have called a service man that is related to my landlord but he won't come and work on it, he keeps putting me off. I have also noticed that when I continually flip the off/ to heat switch on thermostat it will finally kick on. Please give me some ideas as to what may be wrong. I am also worried that it may catch fire. Thanks!
Sharp Advice
12-21-01, 05:18 PM
Hello busywith2kids and Welcome to the Heating and Cooling Appliance forum and our Do-It-Yourself Web Site.
Based solely upon the information you posted, one of the most likely causes is a restricted intake air supply or warm air flow thru the ducting and or to and though the registers in the rooms. Check the filter. Replace or clean as needed. Open all warm air registers fully.
Could be a piece of furniture is too close to the intake air supply and restricting the intake. Could be a defective blower motor that spins too slowly or any of many other air flow problems.
The above conditions will still allow the fan to run but the restricted air flow causes the furnace to overheat internally which then activates the high limit safety switch which in turns cycles the burners off until the firebox cools down some.
Other possible and or probable causes:
Assuming the firebox {Heat Exchanger} isn't cracked and or the burner flames aren't smothering, etc.
Defective Glow Coil: {If equipped with one}
The glow coil may glow but just be too weak to allow current to continue to flow to the coils. The solenoid coils are also part of the electrical loop and may effect proper glow coil operation or functioning.
Defective Spark Igniton Module.
Defective Gas Valve Solenoid:
The gas valves solenoid is internal.
Take the entire gas valve unit to your local appliance parts store and have the entire assembly and parts tested.
Defective Gas Valve:
Remove entire unit as an assembly. Take the entire assembly to your local appliance parts store for testing. Gas valves are not repairable. Replacement is the only option if defective.
CAUTION: Do Not attempt to repair the gas valve! This is a non repairable item!
Flame Sensor:
This part is located on the burner or near the pilot assembly. If it's defective, it will cause the glow coil to not function or cause the problem your discribing. You can test this part with a continuity tester or an ohm meter. However, do not soley rely on this test to prove the part is functioning correctly. Cleaning it may solve the problem.
If the burners are cycling on and off, most likely it's cycling because the flame sensor element is dirty, defective or has a faulty connection.
Possible the fan ON switch is defective.
Could be the high limit switch is defective.
FYI:
The do-it-yourself person can do electrical tests and continuity tests on several of the parts. There are parts such as flame sensors, solenoids, gas valves, etc. when neither electrical tests and continuity tests will provide proof positive the part is actually functioning correctly. Therefore, do not rely solely on either test.
TIP:
The only positive proof any part is functioning correctly, is to carefully remove the part or parts you suspect to be the potential problems, and have the local appliance parts store personnel run the required tests.
Appliance parts dealers carry replacement parts for all appliances and are listed in the phone book under appliances.
Suggestions:
Read the manufacturers online web site for product information, problem solving methods, disassembly, reassembly methods, repair proceedures and instructions, pictorials and schematics, which may be available online.
Check the ARCHIVES, within this forum, for other postings on this topic and the replies offered.
Regards & Good Luck
Tom_Bart....TCB4U2B2B.....Company Enterprises
Fast.....Fair.....Friendly & Highly Efficient.....:D
Gas Appliances Forum Moderator
Energy Conservation Consultant & Natural Gas Appliance Problem Diagnostics Technician.
Based solely upon the information you posted, one of the most likely causes is a restricted intake air supply or warm air flow thru the ducting and or to and though the registers in the rooms. Check the filter. Replace or clean as needed. Open all warm air registers fully.
Could be a piece of furniture is too close to the intake air supply and restricting the intake. Could be a defective blower motor that spins too slowly or any of many other air flow problems.
The above conditions will still allow the fan to run but the restricted air flow causes the furnace to overheat internally which then activates the high limit safety switch which in turns cycles the burners off until the firebox cools down some.
Other possible and or probable causes:
Assuming the firebox {Heat Exchanger} isn't cracked and or the burner flames aren't smothering, etc.
Defective Glow Coil: {If equipped with one}
The glow coil may glow but just be too weak to allow current to continue to flow to the coils. The solenoid coils are also part of the electrical loop and may effect proper glow coil operation or functioning.
Defective Spark Igniton Module.
Defective Gas Valve Solenoid:
The gas valves solenoid is internal.
Take the entire gas valve unit to your local appliance parts store and have the entire assembly and parts tested.
Defective Gas Valve:
Remove entire unit as an assembly. Take the entire assembly to your local appliance parts store for testing. Gas valves are not repairable. Replacement is the only option if defective.
CAUTION: Do Not attempt to repair the gas valve! This is a non repairable item!
Flame Sensor:
This part is located on the burner or near the pilot assembly. If it's defective, it will cause the glow coil to not function or cause the problem your discribing. You can test this part with a continuity tester or an ohm meter. However, do not soley rely on this test to prove the part is functioning correctly. Cleaning it may solve the problem.
If the burners are cycling on and off, most likely it's cycling because the flame sensor element is dirty, defective or has a faulty connection.
Possible the fan ON switch is defective.
Could be the high limit switch is defective.
FYI:
The do-it-yourself person can do electrical tests and continuity tests on several of the parts. There are parts such as flame sensors, solenoids, gas valves, etc. when neither electrical tests and continuity tests will provide proof positive the part is actually functioning correctly. Therefore, do not rely solely on either test.
TIP:
The only positive proof any part is functioning correctly, is to carefully remove the part or parts you suspect to be the potential problems, and have the local appliance parts store personnel run the required tests.
Appliance parts dealers carry replacement parts for all appliances and are listed in the phone book under appliances.
Suggestions:
Read the manufacturers online web site for product information, problem solving methods, disassembly, reassembly methods, repair proceedures and instructions, pictorials and schematics, which may be available online.
Check the ARCHIVES, within this forum, for other postings on this topic and the replies offered.
Regards & Good Luck
Tom_Bart....TCB4U2B2B.....Company Enterprises
Fast.....Fair.....Friendly & Highly Efficient.....:D
Gas Appliances Forum Moderator
Energy Conservation Consultant & Natural Gas Appliance Problem Diagnostics Technician.