Need Some HVAC Advice

[scesnick]

I have a forced air system in my house with a two ton air handler. It is pretty basic really. I have no air conditioning at all and my thermostat is just a basic Honeywell round type thermostat with no A/C capability.

My problem is that last night I woke up at 3am and it was super hot in my houe and the air handler/blower was still running. I turned the thermostat down to 60 and it still didnt turn off. I waited and waited and it never did turn off. I had to shut it down with the breaker.

I am guessing my problem is my thermostat. Am I correct?

 

[murphy1244]

Thats a good start. The stat should have a off position, Try it if it shuts down with that change the stat. If not you may have a stuck relay.

 

[scesnick]

Thats a good start. The stat should have a off position, Try it if it shuts down with that change the stat. If not you may have a stuck relay.

Actually, no off position on this particular thermostat. You just turn it all the way down.

 

[radioman]

on thermostat - there should be 2 wires, if not 3 (for fan only operation). I'd disconnect that one wire ( both if you are not sure, the wires should not be touching) and see if it stops running. If thats the case, then bad thermostat and you can replace it yourself. If it still running then the problem is back at the furnace. If the problem is at the furance, call a pro, since there can be dangerous voltages to work with in furance if you are not sure how it works.

 

[murphy1244]

On your stat is there any other control besides the dial?

 

[scesnick]

On your stat is there any other control besides the dial?

No, i don't have A/C at all ( live up in the mountains). This is the exact one i have. But not in celsius.

 

[murphy1244]

Pu ll the front cover off and look inside.... Two wires?

 

[scesnick]

Pu ll the front cover off and look inside.... Two wires?

Unfortunately i am at work right now so i can't look inside. Just looking for advice for when I get home to look at it.

 

[murphy1244]

Otay, Pull off the bezel and look inside you should see two wires in there, disconnect one and the furnace should stop. The stat is just a switch. let me know what happens. DO NOT replace stat WITHOUT shutting down the POWER to the furnace. If it does shut off replace stat.:confused2:

 

[rgs03833]

Otay, Pull off the bezel and look inside you should see two wires in there, disconnect one and the furnace should stop. The stat is just a switch. let me know what happens. DO NOT replace stat WITHOUT shutting down the POWER to the furnace. If it does shut off replace stat.:confused2:

Take cover bezel off, look for the Glass Sealed Tube inside Liquid Mercury / Switch. Take a Qtip and move that to see if it get stuck cause sometimes dirt / grimes get on top of that and it get stuck through time. Also, make sure the Spring Coil move freely too. Lastly, remove one of the Wire inside if the above steps failed and you Furnace should Stop.



Last but not leaset, hope it's the only problem, LOL

Good article here:

How room or building or wall thermostats work

TIPS:

I always spray some air in the Stats after Fall (September) cleaning. Even though the Stats are Cheap. Why bother spending the money if you can keep the dirt of grimes off easily .

 

[grsthegreat]

best to lose that old style thermostat and replace it with a more modern electronic unit. They give you automatic options to lower temps at night (easier to sleep if its cooler) and auto warm up before you wake up.

You can always play with the mercury HEHE... i used to do that when was a kid. Before i learned that doing so will destroy all your brain cells..... who knew.

Not like it hurt me any

not like it hurt me any

not like it hurt me any

 

[kenmac]

How old is the unit ? does it have a circuit board that controlls the fan? Or does it have a combo. fan/ limit switch like this ?

It may or may not have the small white button sticking out

 

[TRR]

Also, those mercury bulbs require a thermostat to be level in order to work correctly. If they are off level a little the temperature will be different than indicated. and if they are off level a lot, the thermostat won't work correctly (as in always on or always off).

 

[scesnick]

thanks for the info guys.