Upstairs heat not working

jack71888

I have central gas air and my downstairs is working, blowing heat, whereas the upstairs stopped working. It works for cold air if I turn down the thermostat, but for the heat nothing comes out.

jack71888

Jamie Hall

Same thermostat? Or two different ones?

jack71888

Two thermostats. One downstairs and one upstairs 

Jamie Hall

The most obvious things is... is the upstairs thermostat actually working? Can you perhaps swop thermostats? Does the upstairs thermostat need batteries, and are they fresh? After that sort of thing, it really comes down to tracing back through the wiring to find out why the upstairs heating isn't getting the word.

jack71888

The upstairs thermostat is working because when I switch it to Cool it turns on and starts blowing cool air. Only when I turn it to heat does nothing come out.

jack71888

Is it possible the furnace is in the attic? And there’s a problem with that furnace?

MaxMercy

jack71888 said:

The upstairs thermostat is working because when I switch it to Cool it turns on and starts blowing cool air. Only when I turn it to heat does nothing come out.

Not necessarily. If it's a digital programmable one, it uses a rudimentary processor and these sometimes get a bit flipped. Disconnect the wires and batteries for a few minutes and hold down a couple of buttons to fully drain it. Put in new batteries and wire it back up to try again.

Also, if it has a mechanical AC/FAN/HEAT switch(s), these switches sometimes get intermittent contacts as they age. Try snapping it (them) through the positions a dozen times or more. If you have some circuit safe contact cleaner, put a tiny bit in the switch. Do NOT use WD40.

Jamie Hall

jack71888 said:

The upstairs thermostat is working because when I switch it to Cool it turns on and starts blowing cool air. Only when I turn it to heat does nothing come out.

All that proves is that the AC side is working. It proves nothing about the heating side.

JUGHNE

Very common to have a 2nd furnace in the attic.
Have you looked?

Also you do not want to turn the cooling on when it is cold outside. Just run the fan switch to "on" to see if there is power to the possible second unit.

Are there air filter grills in the 2nd floor ceiling?

JUGHNE

Is this a new house for you?
If your house is not a duplex or condo.....how many outside AC units do you have?

Jamie Hall

I hadn't thought of two furnaces... I suppose it could be. However, I still think that verifying that the thermostat and the associated wiring are working properly might be the first thing to do...

jack71888

Yes, I checked the attic and there is a furnace there. Yes, this is a new house for me. It seems that the pilot is off. How do I light it?

jack71888

jack71888

It keeps turning on for about a minute and then it turns off.

SuperTech

No pilot flame on a new high efficiency furnace like that. It has a hot surface igniter that glows red hot to ignite the fuel.  
That furnace has an LED diagnostic light on the control board of the furnace.  It will flash a code to give you an idea of why it is not firing. The codes are usually on the back of one of the front panels. I suspect that it is a pressure switch issue if the igniter never starts glowing.  Check to see if anything is blocking the tubing for the switch.  

HVACNUT

You don't light a pilot. Its electric ignition. 
Turn off the main power switch for 5 minutes. Turn it back on and wait by the furnace. It might take up to 5 minutes to go into the heat cycle depending on the thermostat and, or circuit board.  
First the inducer fan should start (lower right side in your third pic). 
Then watch (not too close) through the round glass window for the burner compartment. 
Within 30 seconds you should see a bright glow, or a series of sparks followed by the main burners.
If the main burners stay on, then the blower motor should come on soon after. 
If this sequence doesn't complete, it might go into recycle and try again. But after a while, the board will show a diagnostic code. Look through the lower door window for the blinking light(s). 
Since you are new to the home and are not familiar with your heating systems, it might be a good idea to shop for a good HVAC contractor. For instance, in the second pic, the air filter doesn't even cover the full height of the return. You might even need one now depending on the issue. 

JUGHNE

Does the furnace fire for about a minute then off
OR
does the small fan just run for that minute?

jack71888

Just a small fan runs for that minute. There is nothing glowing.

Based on the code it seems to be saying that the “pressure switch is stuck open.” I don’t know what that means.

jack71888

Turning it off for five minutes did not work. Still no glow

Jamie Hall

Probably means exactly what it says, @jack71888 . There is a pressure switch on the burner which checks to see if the burner fan is running. If it's stuck open -- or the fan isn't running -- it will keep any further activity from happening.

HVACNUT

From the 3rd pic (this is the 1st floor system so we're assuming they're similar models, but now horizontal) the black cylinder with 2 wires and 2 grey hoses. One hose goes to the inducer fan. Remove the hose from the fan side and gently inhale on the hose. You should hear a click in the pressure switch. You can try repeated short inhales and hear it click, and unclick when you stop inhaling. Also make sure the bung that the hose connects to on the fan housing is clear. Restore power and try again.
The pressure switch is a safety and makes sure the flue gases can escape out the chimney. If it doesn't work, check for a chimney blockage. Is it vertical out the roof? Could be a birds nest or stuck squirrel up there.
If none of the above works, you'll need a pro. 

fenkel

Check to see if system is full of water...i have had the condensate line plug and the pump stop..turn on furnance and listen to induction  fan. ,not blower fan. Now,if it sounds like a egg beater beatings eggs, your system has water in it..

seattlepioneer

I would recommend AGAINST a homeowner trying to diagnose pressure switch issues.

There are too many reasons why a pressure switch doesn't close, and many of them are safety related.

Furthermore, the usually DIY solution is to replace the pressure switch, which is usually a waste of time and money.

I would look for an Honest, Competent repairman to diagnose the reason why the pressure switch isn't closing. An easy way to verify that you have a competent repairman is to ask to see the manometer he will use to test the pressure switch.
If your repairman produces an obviously used manometer with a variety of fitting and tubing attached to it, you have your man.

If your repairman produces a manometer that is new and nicely packaged, he at least has some of the equipment he needs, but probably not the experience to use it properly.

Most repairman wont have a manometer to show you at all. I would send those guys packing and refuse to pay them. They are dishonest and/or incompetent.