Heater

[John a]

Looking for some advice I have a Rheem furnace it's about two years old about a month ago it was trying to ignite and then it would kick out and would try again sometimes it ignites and sometimes it doesn't I replace the flame sensor and gas valve and didn't work when this happens I can hear the igniter Clickin for 10 seconds or so and then it would click off and then it would retry this doesn't happen ever time it goes on maybe 3 or four times a day some time none the hole day any advice on this would greatly be appreciated thank you for your time I believe it's 10 or 11 not detecting flame when this happens I'll watch I here the igniter go for 5 to 10 sec no flame then shut down and re try

 

[Jadnashua]

The position of the flame sensor is important for proper operation. Double-check the install verses the installation instructions.

Does this happen when other gas devices are on? It could be a supply problem...not enough gas getting there because of a bad regulator, or, the gas line too small, or too many devices being fed from a too small of a line.

If it's drafty, sometimes, that can blow the flame away from the sensor, and it won't detect the burner was lit.

 

[Sponsor]

 

[John a]

The position of the flame sensor is important for proper operation. Double-check the install verses the installation instructions.

Does this happen when other gas devices are on? It could be a supply problem...not enough gas getting there because of a bad regulator, or, the gas line too small, or too many devices being fed from a too small of a line.

If it's drafty, sometimes, that can blow the flame away from the sensor, and it won't detect the burner was lit.

When this happens I looked where the igniter is I can hear a clicking but I do not see The pilot light then it shuts down in retries after three or four tries I'll turn the furnace off wait about 10 seconds and then it usually starts up any suggestions thank you

 

[Jadnashua]

Systems with an igniter, often do not have a standing pilot, and it goes from all off to main burner on. Once that completes, after a very short time, a flame sensor will determine if it actually lit the burner. If it didn't, it will go into post-purge mode to vent the gas buildup before it will try again after a delay. Most will only try that sequence a few times, then trigger a fault light waiting for you to reset it. There often is at least a couple of other safety sensors to verify things are working properly like maybe a vacuum sensor to determine if the air supply is viable without restrictions, a high temperature cutout in case things got too hot, etc. Any safety interlock must also be working for the system to eventually generate heat.

A flame sensor can be made several different ways: optical (could be dirty), or thermistor (electrical resistance changes with temperature), and probably others. The sensor must not have become displaced from its properly location and the leads to the control board must be intact without breaks or corrosion.

Main burner ignition depends on first the igniter actually generating a spark, then the gas valve actually opening with adequate gas pressure and volume available, then the flame sensor to allow the burner to remain on until the thermostat is satisfied. If you hear a clicking, you have a spark type igniter...there are other types, generally glow (electrical resistance - sort of like the heating element in a toaster) that get hot enough to ignite the gas without a spark, but those don't generally make clicking sounds.

 

[John a]

Systems with an igniter, often do not have a standing pilot, and it goes from all off to main burner on. Once that completes, after a very short time, a flame sensor will determine if it actually lit the burner. If it didn't, it will go into post-purge mode to vent the gas buildup before it will try again after a delay. Most will only try that sequence a few times, then trigger a fault light waiting for you to reset it. There often is at least a couple of other safety sensors to verify things are working properly like maybe a vacuum sensor to determine if the air supply is viable without restrictions, a high temperature cutout in case things got too hot, etc. Any safety interlock must also be working for the system to eventually generate heat.

A flame sensor can be made several different ways: optical (could be dirty), or thermistor (electrical resistance changes with temperature), and probably others. The sensor must not have become displaced from its properly location and the leads to the control board must be intact without breaks or corrosion.

Main burner ignition depends on first the igniter actually generating a spark, then the gas valve actually opening with adequate gas pressure and volume available, then the flame sensor to allow the burner to remain on until the thermostat is satisfied. If you hear a clicking, you have a spark type igniter...there are other types, generally glow (electrical resistance - sort of like the heating element in a toaster) that get hot enough to ignite the gas without a spark, but those don't generally make clicking sounds.

Is it possible that the igniter is not working all the time I came home from work today and the furnace wasn't working I shut the power off reset it and it took five or six times before it would actually like it kept going into safe mode so I'm wondering if it's possibly the igniter I can hear it clicking and I thought I looked and I didn't see a spark then after one or two more times of a clicking the flame Went on

 

[Jadnashua]

If the wiring is corroded or the connections are loose, it might not be making a very intense spark. Can you hear the gas valve opening?