hvac question

[GRIMJIM]

Any heating and air guys here?

I woke up the other day and it was 55 degrees in my house. I have a programmable thermostat and every once in a while the furnace doesn't come on. Not all the time just once in a while.

What's the problem? Do I need a new thermostat? Is there some kind of relay on the furnace I need to replace?

I'd appreciate any help I can get.

[45-70.gov]

my  house  just gets  cold if no one puts  a log  on

[Spanky]

What do you have to do to get the furnace to restart?

Do you have to push a reset on the furnace itself or do you have to adjust the thermostat?

There is a flame sensor in your furnace that will shut down the furnace if it does not see a flame. The sensor works on a timer. When your thermostat contacts close (or gets to a preset temp.) it sends the signal to your furnace motor which pumps fuel through a nozzle and ignites electrodes to burn the fuel.
If the flame does not ignite for some reason, the sensor will shut down the whole unit. This keeps the fuel pump on the furnace motor from continuing to pump raw fuel into the fire box.

If the flame sensor shuts down the furnace you will have to push some kind of reset button on the unit before you can try to start it again.

When your furnace goes out if you just have to adjust the thermostat to get it started it's probably the thermostat.

If you have to push the reset on the furnace itself it's something with the unit. Could be it just needs servicing (nozzle cleaning, electrode adjustment, etc.)



Spanky

[GRIMJIM]

Thanks for the quick response.

If I adjust the temp the furnace kicks on, I have never had to reset anything. It is an older furnace so there is not a diagnostic panel or anything. Natural gas, forced air system. The thermostat is an energy star programmable type.

[Matt]

Thanks for the quick response.

If I adjust the temp the furnace kicks on, I have never had to reset anything. It is an older furnace so there is not a diagnostic panel or anything. Natural gas, forced air system. The thermostat is an energy star programmable type.

Check to make sure that the battery light is not on or is in a normal status. Low battery will cause them to kick on later than you want or this has been the case in all that I have come upon.

Depending on the age it might be time to replace it... If you got 4 or more years out of it you done good...

Matt

[Spanky]

Check to make sure that the battery light is not on or is in a normal status. Low battery will cause them to kick on later than you want or this has been the case in all that I have come upon.
Depending on the age it might be time to replace it... If you got 4 or more years out of it you done good...

Matt

Exactly right.



Spanky

[squirrellluck]

grimjim What brand/ model is your furnace? Does it have a standing pilot or spark/hot surface igniter. Matt is right if you have a tstat that runs on batteries and not 24 volt control voltage. Depending on age it may have a flame sensor that locks out after 3 failed attempts to ignite If this is occurring you can sometimes correct this by removing the sensor and cleaning it w/steel wool. Let me know and we may be able to figure it out over the net. I am a service tech for a heating and air company.

[squirrellluck]

PS if it is the tstat you can pull the front off so you can see the wiring terminal. Look to see if you have a terminal marked c or b and if it has a wire attached. If it has a wire on c/b it is 24 volt in which case batteries won't fix it.