The furnace is part of an HVAC or central heating system used to generate heat. Typically this is done with gas, a heat pump, or an electric element. For hot water and radiator based heating, use the boiler tag.

learn more… | top users | synonyms

2
votes
1answer
263 views

What could be causing vibration in my furnace?

I have a vibraton in furnace only when flame is lit. Blower motor seems fine. Is this vibration normal? Recently replaced inducer motor. Heat exchanger has been replaced once. Does not appear to be ...
1
vote
1answer
75 views

Why would only 1/3 of my registers be blowing warm air?

I have a Coleman gas furnace in a wall space in my house which somehow shares the blower on my a/c unit on the roof because it turns on when furnace is called to start, though it does bump up after a ...
1
vote
1answer
168 views

What could be causing my furnace burners to fire up, then shut off due to partially open door?

I have a 10 year old Carrier gas furnace that keeps shutting off every 24-48 hrs. First I thought it might be the flare sensor but then I checked the bottom door and it wasn't completely closed. I ...
1
vote
1answer
2k views

What could cause a Trane furnace to not start heating?

I have a newer (2007?) Trane XL90 (model: tdx2b080a9422aa)forced air gas furnace. The problem I am having is the burner and fan will not start. The thermostat is set at 67 degrees and shows it is ...
1
vote
1answer
197 views

Can I relocate my furnace exhaust?

When my new furnace was installed, the vent was put outside the house next to landscaping bushes. It has killed one of my bushes. It used to be vented up to my roof and out. Can I move this outside ...
0
votes
1answer
29 views

Limit switch is good but no heat

I am getting a 4 blink indicator saying my limit switch is bad. I tested the switch and it is good. What else could it be?
0
votes
1answer
96 views

How do I check if this furnace switch the blower to second speed

My furnace is overheating and I suspect that the blower motor does not go into high speed. Can anybody say what is the cause or how can I check if it indeed switches to high speed? Here is the wiring ...
0
votes
1answer
272 views

Where do I connect the C wire in my furnace?

I am upgrading my thermostat to a Nest, and would like to add a common wire. My current furnace controller doesn't have a C terminal, but the current thermostat wire has 2 unused wires (black and ...
0
votes
1answer
95 views

Is there any way to stop the air leak through my furnace without compromising its operation?

My house has an 80% efficiency gas furnace in an interior mechanical closet with the return air path below the furnace and through a grille under the closet. However, since the furnace is not a sealed ...
2
votes
0answers
292 views

Are w1 and w2 both energized during a second stage heat call from the thermostat?

Short version: does two-stage thermostat always close W1 circuit when it closes W2 circuit, or they might be closed independently? Long version: I have two-stage furnace, currently connected to older ...
2
votes
0answers
264 views

Why won't my condenser turn on when I run my heat pump?

I have a York Affinity condenser. When I run my heat pump, I expect it to turn on somewhere in the cycle but it doesn't. It generally does this once a year. The usual fix is to cycle the power of the ...
2
votes
0answers
211 views

How do I know if my high limit and low limit are set correctly on my aquastat?

I have a boiler that is only providing heat for my forced hot water baseboard system (4 zones). I've always thought that the high limit on the aquastat was too low (the temperature on the boiler ...
1
vote
0answers
24 views

Why would a gas furnace shut down after 20-30 seconds?

I have an 18yo Lennox gas furnace (Modle 23G89). It starts and runs for 20-30 seconds then shuts off. The light blinks in a steady state- no code. Then I removed the filter to guarantee a clogged ...
1
vote
0answers
23 views

How to clean carbon build-up on Honeywell whole house air purifier made of aluminum?

Bought a house recently that has a Honeywell F300 whole electric house air purifier/cleaner. The cell's aluminum fins have a black baked-on dust that I expect is preventing the unit from working as ...
1
vote
0answers
32 views

What type of furnace vent pipe is this?

I need to extend my furnace vent pipe up 2 foot above the ridge of my roof to comply with IBC. So I need to couple this pipe somehow and extend it up. Any idea what type of pipe this is and how I ...
1
vote
0answers
38 views

Testing the exhaust of a natural gas furnace?

I recently had maintenance performed on my natural gas forced-air furnace. During this maintenance, the technician went outside and used an electronic handheld device with a wire-attached probe to ...
1
vote
0answers
25 views

Identify/troubleshoot this millivolt furnace valve

I have an old millivolt gas furnace that's stopped working. The pilot stays lit fine and the thermopile generates about 360 millivolts, and there's no problem at the thermostat (checked voltage and ...
1
vote
0answers
77 views

Can I use the T terminal in my furnace as the C for a Wifi Thermostat?

I've read many posts on this, and believe I know what to do, but want to make sure. My furnace (a Lennox G14 Series) does not have a C terminal which needs to be connected to the C terminal in my new ...
1
vote
0answers
438 views

Why is my furnace blower running at low speed?

My Payne gas furnace (PG8UAA 42091) automatically shuts down after it lights and burns for two minutes. It then gives a 33 fault code. I've done some research and some testing and have narrowed the ...
1
vote
0answers
69 views

Furnace reset problem

I have a new Goodman high efficient furnace model number GMH950703BXAG1. And this is the problem I'm having now: Turn on the furnace power (after ~1 hour off) Turn on the thermostat with Temp ...
1
vote
0answers
125 views

How can I install a furnace register in a kitchen-cabinet toe kick?

I'm planning to install new kitchen cabinets. I'll be covering up the kitchen's existing sidewall diffuser with new cabinets, so I'd like to relocate it to a new register in the toe kick of the sink ...
1
vote
0answers
114 views

Why won't a NEST that shares control of a furnace with a conventional thermostat turn on the heat?

I have three floors in my home. The bottom floor has its own gas furnace and the 2nd and 3rd floors share another gas furnace. Everything was working great until I added a NEST to the first and ...
1
vote
0answers
114 views

How should I shut down a woodburner that is attached to an electric furnace for the night?

I have a Monarch Add-A-Furnace wood burner connected by ductwork to my Armstrong Air electric furnace. I use the wood burner when it gets really cold outside, but shut it down at night because I do ...
1
vote
0answers
1k views

Why is my furnace limit tripping?

My furnace is tripping the high limit. It is a Downflow Payne 90+ have replaced the limit switch. I pulled the blower door off and checked all vents to ensure they are open and it still short cycles. ...
1
vote
0answers
462 views

Why is my furnace blowing hot air outside?

So I have been having trouble heating my home. I noticed today that there is a vent blowing hot air outside. It is not the return, chimney or venting. Any ideas other that the builder thought we ...
1
vote
0answers
1k views

What's causing my draft inducer to stay on?

I have a new, 3-year old, high-efficiency, gas furnace in my home. I recently realized that my draft inducer, which normally kicks on before the burners and before the main blower, is not stopping. ...
1
vote
0answers
259 views

How can I clean out the pressure switch port at the inducer housing on a Lennox G40UH furnace?

I have a Lennox G40UH(x) furnace, but the gas does not ignite, because water may have entered the system while raining, or the the pressure switch port at the inducer housing has just to be cleaned. ...
0
votes
0answers
4 views

How to wire a Feeder Furnace?

I have a feeder oil furnace and I need to know how to wire the oil burner to the oil control box please help
0
votes
0answers
15 views

New Furnace won't turn on after trying to install thermostat

I had a furnace installed about a year ago in my basement. The installer left the wires sticking out of the wall for me to install a thermostat. He said if you want to turn the furnace on, just ...
0
votes
0answers
16 views

What can cause short life of the igniter in furnace?

what could cause short life of silicon nitride 80v,IGN00145.furnace trane xcm95 2years old put in 3rd igniter.
0
votes
0answers
30 views

Furnace blower intermittently stops working

The blower on my furnace is set to be on constantly. The last two nights in a row I have woken up in the middle of the night to hear that the blower is not running and that the temperature is dropping ...
0
votes
0answers
24 views

What could cause the furnace to not come on after airing out the house?

Turned the furnace system off and manually turned fan on at the thermostat to air out the house after staining woodwork. Now the system is turned back to Heat and Auto Fan but will not cycle on. The ...
0
votes
0answers
38 views

Main burner will not light, but the pilot is ok

I have an old Heil unit 100,000 BTU, it has been working fine up until Tuesday night. The pilot light is on. I replaced the gas control valve, I know it has limit switches should I replace them all or ...
0
votes
0answers
47 views

With registers fully open I have unbalanced air flow upstairs vs downstairs

Upstairs the airflow is OK Downstairs I have 4 registers. Three out of four have very weak air flow while the fourth one is blowing like hell Is the problem in the furnace or in the air ducts?
0
votes
0answers
56 views

Asbestos in my furnace closet - should I get rid of it?

I have a home built in 1958 with a closet inside the house that contains the furnace. When the house was constructed this closet was lined with asbestos as a safety measure. How dangerous is it for my ...
0
votes
0answers
28 views

How do I get the main furnace blower to come on when the wood burner furnace calls for heat?

I need to know how to wire the gas furnace blower to come on when the wood burner's blower kicks on.
0
votes
0answers
59 views

ComfortMaker GUH075 series high-efficiency (93%) furnace isn't making heat

It worked a couple of days ago but today the fan blows but the burner doesn't seem to come on. The status indicator inside the access panel flashes four times but I can't find any reference to tell ...
0
votes
0answers
969 views

Where to connect a c-wire on a furnace with existing two wire mercury thermostat

My existing thermostat is an old mercury two wire device, heat only. Looking to upgrade to a better model, but I need to run a c-wire. I don't know where to connect the wire at at the furnace, any ...
0
votes
0answers
49 views

Options for humidifier

Winter is approaching and the cool weather is making the air dry in our home. We're using room humidifiers but want to install a humidifier which can go on our furnace. However, we have very limited ...
0
votes
0answers
246 views

Furnace not working properly with digital thermostat

I have been attempting to use several different types of digital thermostats to replace my old mercury thermostat, however none of them are able to control the furnace properly. All of them are able ...
0
votes
0answers
60 views

Steps for annual maintenance on a fuel oil furnace?

We have fuel oil and this year I'd like to try and maintenance the furnace myself: By "maintenance" I mean "clean it up so that it runs well throughout the winter." Just a basic tuneup and ...
0
votes
0answers
50 views

Which should I do first? replacing furnace or resurfacing concrete floor?

I'm going to get two things done in my basement soon (by hiring professionals), but I'm wondering what the right order of operations is. One task is to replace the gas furnace that sits near the ...
0
votes
0answers
318 views

Why is my new high efficiency furnace blowing cold air sometimes?

Why does my new furnace high efficient Payne furnace blow cold air,not constantly but at least 3 different times in a day, my thermastat is set on auto but when the weather is cold outside it will ...
0
votes
0answers
30 views

A/c runs while gas furnace is on

In the winter when gas furnace is turned on, a/c comes on preventing house from warming up. When disconnect is pulled at condenser, house is able to heat. Do not think that system is a heat pump. ...
0
votes
0answers
115 views

Why does my furnace make sounds like a tuba when kicking on?

I have a 21 yr old Bryant furnace. Recently it started making a horrible noise when the heat first kicks on. It sounds like someone playing the tuba. It only lasts a few seconds, but it's loud ...
0
votes
0answers
61 views

Can I use my forced air furnace to heat water for radiant heat too?

I moved from Europe to USA 4 years ago and I was wondering if it's possible to combine forced air heating with the heating that uses radiators. My idea is to use the furnace for forced air to heat up ...
0
votes
0answers
1k views

Why would said gas furnace keep shutting off?

Seems that I have a gas furnace that is having some sort of heat/air sensing issue. Basically it shuts off after running for a minute or two. But if I remove the top plate of the furnace itself it ...
0
votes
0answers
279 views

How can I provide my furnace with outside combustion makeup air?

I cut a 6" opening in an insulated door into the utility room then installed a 6" metal duct with a plastic exterior vent cover. I put 6" insulated flexible duct on the interior stub and let it hang ...
0
votes
0answers
394 views

Can I manually run the blower on my Lennox G12Q3 furnace?

I have a Lennox G12Q3-120-6 model furnace. Does anyone know if there's a way to manually run just the blower without heat? There are no switches on the outside that I can see (other than the power ...
-1
votes
0answers
28 views

Where can I find a furnace wiring diagram?

wiring diagram missing on electric furnace. how can i tell where all the control wires go ? older Coleman electric furnace (1986 presidential ) maybe ? in a mobile home. i really need help here as it ...