'Auto' Setting on Thermostat does not turn heat on
 

does anyone know how i can see what the problem is? when the stat is set on HEAT and 'AUTO' and i see the room temp is definitely lower than the set temp, nothing turns on...

if i set the stat to ON, i hear the fan blows... the air doesn't feel warm though... so i don't know if the burners kick on...

does anyone know how i can diagnose for a bad stat??? should i clean the components of dust???

ON is just fan, so yeah no heat.

Does you heater have a pilot light? Maybe it's out.

You can also try raising and lowering the temp setting past the current room temp to see if you here a click. Most digital thermostats click when they call for heat/air.

checked the pilot light.. it is on... and it seems like it is the only thing on... with the STAT set 'ON' and 'HEAT', the fan runs but i would expect to see all the burners on in addition to the pilot light...

its an old school round wall STAT... it is currently set wayy above the current room temp... would i hear the click at the stat or at the furnace???

Ok, round wall most likely has a blob of mercury inside it so no click. If you pop the lid off of the stat you can see the blob move around as you turn the dial. Sometimes there is a little flash when the mercury makes contact as the electric jumps. That's about my extent of my knowledge though :sorry:

If your furnace is very old check for pilot light. I think anything recent won't have one though.

yeah the unit has to be about 30 yrs old.. it is an old american standard... i was thinking about replacing it yet since i haven't moved into the house yet... but i need to run the heat in the winter so the pipes don't burst... so if it is the stat that need to get changed, ill just replace it until im ready to move in and change the whole furnace...

On is just for the fan (some like to have it running all the time to move and filter the air), Auto turns it on when heat/ac is needed. Your Stat may be bad.

okay how do i test for a bad stat?

:dunno: Run to HD and buy a cheap T-Stat and wire it up and see if the furnace fires up?

^^ +1. The on/auto switch only controls the fan.

The lack of heat is another problem. Try setting the fan to auto, then set the thermo to a high temp. If the fan doesn't kick in within a couple of minutes the heater is not getting a "go" signal from the thermostat. Might check the connections on the back and see if you are getting power to the thermo.

i will rip it out tomorrow to check the connections... i searched online and it says to jump the R and W wire to test the heat??? not sure if there are any HVAC guys on here???

Does your furnace try to kick on at all when the stat is set on Auto and the dial is set above the current room temperature? If the furnace does try to kick on, but does not blow heat, the furnace itself may not be properly going through its purge cycle and tripping itself out on a safety. If the furnace does not try to start its purge cycle at all, I would say you have a bad stat. :2cents: I found a lot of helpful information on http://forum.doityourself.com/when I was installing my humidifier. May find some more information & help on there.

Set the thermostat to the lowest setting.
You said you hear the heater come on so it's probably not the thermostat
Pop the cover off the front of the heater and see if it ignites.
If you hear the fan on but no flame chances are the ignitor or the thermocoupler is bad (no I'm not making this up).

it ended up being the thermostat... the fan would kick on when i have it set to 'ON' but the air was not warm... so i figured that the stat was not sending for heat which confirms why the pilot was on but the burners wouldn't fire up...

i took apart the thermostat and touched the 'RH' wire with the 'W' wire... left the fan on 'AUTO' and went down to the furnace... the burners were on and in a few mins the fan kicked on and the air was warm...

went to home depot early this morning and picked up a new digital programmable stat... installed and ready to go... i'll check back after i leave for work...

thanks everyone for your help... the temp inside the house dropped below 32oF overnight and i didn't want the pipes to burst...

Congrats on the repair. Amazing how this stuff always breaks on the coldest night of the month.

thanks.. it was exactly that...

and i never visited that website till now... it looks very useful...

And now with a programmable thermostat, you should be able to lower your energy costs. :woot: win/win

Glad to hear you found the problem :thumbsup: busted pipes would have sucked. that forum has been pretty useful for a lot of my home improvement projects.

i dunno how much it will be reduced.. i only keep the heat at 55oF since no one is in the house with it still being renovated... i just don't want the pipes to burst...

once i move in, i will prob shop around for a more updated model... this American Standard is dirt old and prob 30+ yrs old... it runs like a champ still but i am sure i will save alot more after updating to a newer one...

Furnace

Attachment 85564

A/C unit

Attachment 85565

so my next thread will prob be a poll of Carrier vs Trane... :thumbsup:

Glad to hear you fixed the issue, my igniter went and I was without heat for 3 days, was also worried about my pipes bursting, thankfully got a new part in for cost, glad you got the issue figured out :thumbsup: