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View Full Version : Forced air furnace, never shuts off!



Colin_R6
09-21-2012, 09:34 AM
I almost always have my thermostat set way below the actual temperature in my house, and the damn furnace is constantly trying to cool the house down to where the thermostat is set, with "cold" air from the furnace room. The only way I can actually get the furnace to shut off is if I set the thermostat close to the actual room temp. If the room temp comes up at all, then the furnace just kicks in its "cooling" cycle again and resumes making nose and annoying me.

Furnace is a couple years old (Intertherm M1) and thermostat is a Nest. I'm hoping I can disable this function. Furnace manufacturer doesn't have a phone number or email on their website and I contacted the maker of the home, with no reply yet (only been about three days so far).

ercchry
09-21-2012, 09:39 AM
uh, its your fan. you should have "on" "auto" and "off" ...try "off"

Tomaz
09-21-2012, 10:41 AM
Your thermostat is designed to turn on your furnace/AC until the ambient temp of your home reaches the desired setting. It sounds like it is impossible for your HVAC system to reach that temperature, but it is still going to try.

Your options are:

Stop setting your thermostat to unrealistic goals that your system cannot maintain

Buy air conditioning, so your system can actually cool the house

Turn your thermostat to "off". I am not familiar with the thermostat that you are running, but there is a function to turn the system off somewhere on it.

EDIT: Dude, nice thermostat! lol

http://support.nest.com/

Not as simple as one would think, but basically, it looks as if it would be best to set your thermostat to what the house can achieve. Check the link for thermostat support. Your furnace is fine, the controller is what is messing things up for you.

ExtraSlow
09-21-2012, 10:43 AM
Fancy thermostat doesn't know you don't have AC?

On my thermostat, you can set it to heat only, cool only, Auto, or off. Plus having the fan on Auto or on.

If yours has any of those settings, I think you want it on Auto Fan and Heat only.

vtec4life
09-21-2012, 10:45 AM
I was told to always have it on "HEAT" not the cool setting. Especially if you dont actually have air conditioning. Is there a switch by your thermostat for forced air? I have one that I can turn on and off to bring cool air in at night if I want.

sputnik
09-21-2012, 12:01 PM
Originally posted by Tomaz
EDIT: Dude, nice thermostat! lol

http://support.nest.com/

The NEST looks pretty, but it is pretty limited in functionality. At the end of the day it isn't that much different that a basic programmable thermostat.

The communicating thermostats (Bryant Evolution) are much better but not as "pretty".

LLLimit
09-21-2012, 01:22 PM
Did you hook up your Rh wire accidentally to your Rc slot?

I have a nest too, and I don't have this problem.

JordanLotoski
09-21-2012, 01:27 PM
try your ventilation switch should be close tomyour thermostat

Colin_R6
09-21-2012, 07:06 PM
Thanks for all your replys guys!

I had one of the old classic thermostats hooked up prior to the Nest. The faceplace on it had the usual ["Auto" "Cool" "Heat"] settings on it.. but no lever to actually switch it back and forth among the settings. I looked inside, and nothing was broken - so the damn thing just didn't have the settings.
So basically, what I said there is that the old school basic thermostat had the exact same, err.. behavior.


It sounds like it is impossible for your HVAC system to reach that temperature, but it is still going to try

This is pretty much my assessment of the situation. I was really hoping there might be an easy solution like turning off the Recirc/Cooling function right on the Furnace.

I know the Nest is about the same (maybe even a bit less) functionally than a regular programmable thermostat - the reason it intrigued me is that I work a 4 on/4 off shift. All the regular thermostats are usually only programmable in a weekend/weekday basis. The Nest learns my patterns and governs itself accordingly. At least this is my hope!

And if it doesn't... by golly i've got myself the iPhone of thermostats, lol!


As to hooking it up, and what wire goes where etc - i'll take a closer look. I only have a red and white wire coming out of the wall, I have them plugged into the first and second ports on the top of the left side. I'm hoping you are right LLLimit!

Colin_R6
09-21-2012, 07:22 PM
After some careful digging in their setup area I figure I've got the thing wired up properly etc.

I submitted a ticket with them to see if they have any solutions.
I imagine i'll be contacting the furnace manufacturer somehow and finding out how to over-ride the "Cooling" function.


I wonder if its possible that the old basic thermostat was inherently set at "Auto" and now the furnace is remembering that setting on its own? Maybe my fix is to find another thermostat that will allow me to set it to "Heat" and it will remember that instead.

Mar
09-21-2012, 08:17 PM
There must be a heat/cool setting on it somewhere. My thermostat is a dinosaur and I have to set it to heat only because if I set it to cool without an air conditioning unit it will probably stay on forever. I've never tried.

I have looked at some replacement thermostats in the past and I've noticed you can buy ones for heat only or you can pay an extra couple of dollars and get one that does cool as well, maybe you (or the previous owner) purchased the incorrect thermostat with the cool feature built in and you actually need the cheaper model without that.

suntan
09-24-2012, 11:11 AM
Do you have a OTR microwave or fan that turns on the furnace fan when you turn it on? There should be a box near your electrical panel that controls how sensitive (it's wattage based, I think) the trigger should be. You can open it up and adjust it with a screwdriver.

I had the same problem with my house when I moved in; if I had the lights on the microwave on, the vent fan turned on.

Colin_R6
09-24-2012, 08:35 PM
I found a service manual for it today, and did some reading. I almost think my thermo-couple fan switch might be stuck in the closed position.
Going to take a closer look at it tomorrow morning.
Might also go down to the local HVAC place and try to weasel some free advice from them! haha

LLLimit
10-02-2012, 09:20 AM
2nd generation coming out soon.

http://www.nest.com/blog/2012/10/02/the-next-generation-nest-thermostat/



looking forward to the 3.0 update
:)