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.

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My furnace has a vibration for about a second at the end of the heat cycle.

It runs fine for the approximately 15 minute heat cycle. It appears as though it happens as the thermostat is satisfied and the gas valve shuts off. The vibration is heard upstairs and throughout the ...
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1answer
31 views

What could be causing my Thermostat “R” wire to only be 8 VAC?

I am trying to install a Nest thermostat. It says Rh not powered. I checked with a meter and I get approx 8 VAC reading. What could be causing this? The furnace itself ain't pretty. Update: ...
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3answers
757 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 ...
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49 views

Asbestos? What do you think?

I originally thought so, but now I'm not so sure. Thoughts? It was located around HVAC vents.
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172 views

Where do I connect a C wire in a Rheem Furnace REAB 1415J?

I'm upgrading the thermostat with a Honeywell wifi one. I found all cables at the thermostat end, but can't figure out where to connect the C wire to the furnace (Rheem REAB 1415J).
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1answer
41 views

Heater air intake blows out the flame

The problem I have is the air heater shutting down in windy days and I'd like to figure out how to fix this issue. Here's the setup: The back of the house faces North to an open field which gets very ...
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2answers
39 views

Can I replace my furnace's high limit switch with a comparable third-party part?

I have an older Lennox furnace. The high limit switch (#60T15,130F) has gone bad. I haven't been able to find on-line this part number with the exact temp limit specs, and Lennox no longer carries ...
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1answer
1k views

Connected C-Wire to new Smart Thermostat and Furnace board and still no power

I need help. I've been surfing the internet and have had no luck finding answers to my situation so am hoping for some guidance. I've seen other questions here answered but none that suit my ...
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1answer
122 views

Goodman gas burner not lighting

Goodman warm air gas furnace. Gas burner would not light.Status code light blinked continuously. Igniter glows red hot. I cleaned flame sensor with fine grade sand paper. Checked transformer line ...
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2answers
66 views

No water pressure in heating circuit

I have a natural gas hot water furnace and I can't get heat. First I turn up the temperature at the thermostat and I hear the furnace turn on, the supply line gets hot and half way down the line it ...
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3answers
83 views

Will a 2-stage heat pump cool my upstairs on low stage?

I am currently upgrading my furnace from an oil furnace/AC combination to all heat pump. I am considering two stage vs single stage heat pumps. I understand that two-stage will supposedly give me ...
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1answer
936 views

my furnace fan stays on even when at temperature

I recently installed a 2nd generation NEST thermostat. I'm not home very often, but I was paying particularly close attention to the furnace after installing this thermostat and I noticed that the ...
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1answer
143 views

Why does my gas furnace run once then wont come back on until reset when temps are below 30 outside?

THE PROBLEM: My gas furnace will run one cycle and then not come back on until the switch is reset. Once the switch is reset it will kick on immediately run once and again I will have to reset before ...
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Nordyne furnace doesn't start at all (model gl1ra 090c-12b 903785GA)

What are the reasons this model furnace won't start at all anymore. No sound when I flip the on switch. I already tried replacing the ignitor and that didn't work. Thank you for any help!
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1answer
45 views

What causes furnaces to break in 16 to 20 years?

Why do furnaces need to be replaced in this regularly-occurring amount of time?(http://www.homeenergycenter.com/8furnace_signs.html) Is there something about the physics of the high heat and ...
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2answers
709 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 ...
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1answer
2k 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 ...
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1answer
271 views

Correct Wiring for Furnace Blower Motor

After getting my furnace blower motor replaced, it now runs only in the following scenarios: 1. Mode "Cool" Fan "Auto" 2. Mode "Cool" Fan "On" 3. Mode "Heat" Fan "On" In other words it will not run ...
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2answers
1k 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 ...
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8 views

gmp050-3 goodman furnace 4 blinks cleaned flame sensor , new igniter, runs for 90 secs then shuts off?

I have olm reading on all switches. replaced igniter and the switch inside that measures the temperature when fired up
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2answers
405 views

Lennox G40UH takes a long time for the heat to come on

The digital thermostat lights up with "HEAT ON" but it takes the furnace up to an hour to kick start. Once it does, it puts out heat. We set it to 69 here in Michigan with the outside temp at Zero. ...
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1answer
77 views

New Thermostat installed but compressor comes on immediately

I have a new Insteon Thermostat that I'm using to replace my prior Honeywell t-stat. This is installed to a relatively new HVAC system (both AC and Heat) that DOES have a "c" wire. I've attached the ...
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1answer
35 views

Oil furnace fan won't shut off when “heat” plug is connected to control board

I was changing my thermostat and I attempted to make the swap live without turning power off. When I connected new thermostat, the fan kept running. Ruled out bad thermostat and wire short by ...
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2answers
79 views

Furnace fan works properly intermittently

My furnace fan sometimes stays on and runs continuously. I can stop it by flipping the breaker for the furnace on and off. It then stays off. When heat is called for, the fan comes on again and ...
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1answer
8k views

Why is my water expansion tank leaking?

I live in the northeastern US and we just turned the heat on (oil) and this morning I went down to the basement and saw this: The water is coming from the plumping above something labeled "water ...
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2answers
10k views

Can a washer and dryer be next to a water heater?

I have a GE gas dryer (DSXH47GGWW) that is currently next to an exterior basement wall. I'd like to move it to the opposite wall (shared with the crawl space) right next to the water heater next to ...
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2answers
11k 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 ...
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1answer
44 views

Can't get fan working on thermostat

I recently purchased a new thermostat. My old thermostat worked for heat (no AC either) but the fan wouldn't go on when I turned to "On" (in hopes to move some cool air from the basement up during the ...
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3answers
14k views

Why isn't the spark gap lighting the pilot on my furnace?

I've got a Carrier 58GS natural draft furnace, which has a spark gap for igniting the pilot. Unfortunately, the spark gap has not been successfully doing its job. The spark clicks away as the gas ...
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1answer
20 views

Furnace fan starts slow and is getting slower

here is a sound clip, start at about :55 or listen to whole thing! https://clyp.it/3h54oe2q model is tg9s060b12mp11 luxaire, which comes up as York most places. Anyhow, what's the best way to ...
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1answer
51 views

dissolved brass fitting

this week i had to go check a problem for a long term customer that she was having with her furnace. she had had some company come in and do a furnace service, and a few days after they left, she was ...
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2answers
218 views

My goodman furnace is not igniting my burners

I have a goodman furnace and when it is calling for heat the ignitor comes on and goes off and comes on again and the burners never comes on what could be the problem
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1answer
2k views

Insulating ducts in a crawlspace

Consider a source duct from the furnace/AC. The ducts run in a vented crawlspace. The floors atop the crawlspace are a mix of hardwood and kitchen vinyl. The symptoms are: the longer run vents ...
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3answers
28k views

Adding a C wire to a new Honeywell WIfi Thermostat

I am trying to install a new Honeywell touchscreen WIFI thermostat and need to add a C wire to my terminal inside the furnace (using the help found at How can I add a "C" wire to my ...
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1answer
35 views

RUUD Furnace blowing air but not heat

I have a RUUD furnace that stopped blowing hot air last night. I was thinking that it was the high limit switch gone bad BUT the coil ignites and lights but then goes out again after a minute, so ...
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1answer
207 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 ...
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38 views

Thermostat doesn't control the

I have a 20 years old Weil Mclain furnace that has been working well till lately. All of a sudden, the thermostat has no control on the furnace. I changed the pilot, it worked, but still independent ...
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3answers
41 views

Sealing gas duct vents with silicone

Is it okay to use silicone to seal gas furnace heater supply ducts? If so, do you know how long the silicone will need to cure before the system is useable? Some background: I've been trawling around ...
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2answers
32 views

Condensation on cold air intake

Our home is relatively new (built in 2014), but something I noticed is that the PVC pipe going into our furnace (which connects to the outside of the home) is developing some condensation (which can ...
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3answers
2k views

Which furnace thermostats support variable swing/deadband?

My home furnace is currently controlled by a programmable Honeywell thermostat, but it regularly thrashes the furnace by turning the furnace on for just ten or twenty seconds. It seems that the ...
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0answers
2k 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 ...
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2answers
95 views

Is this flue dangerous?

I had access to a ladder the other day, so naturally I was poking around in the attic of our house where we have lived for about a year. Above the closet where the furnace and water heater are ...
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26 views

Installing Honeywell wifi thermostat - weird wiring

I bought a Honeywell 7 day programmable wifi thermostat (non touch screen model). My old thermostat was wired as: Red - rh & rc Blue - b Green - g White - w I also have an unused blue wire (not ...
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2answers
73 views

What pipe is this?

Hello and please bear with me. I'm no expert when it comes to plumbing but I will try to be as detailed as possible. I'm trying to understand what a pipe does in my basement. The pipe seems to be ...
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1answer
1k views

Why does my gravity vented wall Furnace keep turning off/

We have an Empire gravity vented wall furnace: That turns off. According to the instructions, this is because the vent safety switch. But when I open up the furnace, it appears to be vented just ...
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3answers
128 views

Was this furnace installed properly?

I am looking to answer the following: Was this job done properly, and if not, then how really bad it is? And should I hire this contractor again ? Product: Ruud RGTM10ERBJS 100K BTU 95% ...
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1answer
43 views

question about a gas furnace having to light repeatedly

I am new to this forum, but I will do my best to answer any questions I can (I am a general contractor with a background in engineering and residential construction and machine design) so, here is my ...
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8 views

why does my new yorker boiler start after I turn power off and back on when thermostat is asking for heat?

I have a New Yorker gas boiler for heat and tankless hot water. At times when asking for heat or hot water the boiler does not start, but if I turn power off and back on the furnace will start. Once ...
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1answer
4k 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 ...
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2answers
16 views

Furnace blowing cold air

Furnace wont produce heat. Thermostat is brand new. It Will work fine for a minute then heat come on go right back off. Can't find where filter goes house is old and vents are dirty I thought it's the ...