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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Forced air system blowing cold air through bedroom vents, hot through the rest

I'm in a rental house for the next few months which hasn't been particularly well maintained. It does have a newish looking Goodman gas furnace, yet the gas bills seem outrageous to me ($250 per month ...
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63 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 ...
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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 ...
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217 views

How close can an electric water heater and an electric furnace be to each other?

How close can an electric water heater and an electric furnace be to each other? My water heater is 7 inches from my furnace. I need 4 inches so that I can install a water softener and wash sink. So ...
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634 views

Should I leave the fan switch on my thermostat set to fan rather than auto?

I purchased a new Amanda Furnace in Oct'2013. I am told in order to maximize a warm, consistent room temperature I should set the thermostat to the Fan position rather than the Auto position. Does ...
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1k views

How do I connect a WiFi thermostat to my furnace's primary control?

I would like to install a Honeywell WiFi controlled thermostat to connect to a Honeywell R7184U primary control. My question concerns the "C" wire. The R7184 has the terminals labeled 1, 2, 3 and 4 ...
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1k views

Furnace flashing 4 times (Ducane)

My Ducane furnace flashes 4 times, runs for 5 minutes, and then the burner goes off. When the limit switch is jumped it runs good. What needs to be changed here?
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How do I prevent harmonic resonance hum in PVC vent of newly installed hot water heater?

I just had a new power vented water heater installed (HTProducts Phoenix Light Duty) in our crawlspace. The contractor that put it in used part of the existing 3" concentric vent from the furnace we ...
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257 views

Would a failing igniter cause my furnace to blow cold air?

I noticed tonight my furnace was firing up, but not actually blowing out heat. I turned the thermostat down so it was no longer triggering it, let it sit for a couple of minutes, and then turned it ...
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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 ...
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601 views

Should I replace my Pressure Reducing Valve?

A few weeks ago, my oil-fired water boiler started continuously leaking water out of the pressure release valve on the top of the unit. I know this is leaking steadily because it drains into a 5gal ...
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16k views

Gas furnace kicks on then off frequently

A few times in the past week I will wake up to my furnace turning on, hearing a click when it tries to ignite, then turn off. This will happen for a couple minutes before the furnace quits trying. ...
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583 views

Furnace installation

I have new 2 carrier infinity CNPVP high efficiency direct vent furnaces in my basement for my 3500 sf house. The air intakes for both units are not plumbed outside but instead are drawing air from ...
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307 views

What is this noise coming from my gas furnace?

Whenever I change my air filters in my furnace, I hear a boom noise. The last time I called DEER and they came out and fixed the problem (I can't remember what the part was called that was needed). It ...
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141 views

Legal requirements regarding 100% asbestos duct work [closed]

I am renting a condo. After starting the heater, dusty air came out of the registers, so I called out a company to clean the ducts. They verified the ducts are 100% asbestos and cannot be cleaned. ...
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Why would my Goodman gas furnace start but not stay on for more than 2-3 minutes?

I've got a problem with my 15 year old Goodman furnace. It starts w/o problem, inductor begins working, hot surface ignitor lights up and ignites the gas. Then the main blower starts working and the ...
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7k views

How do I wire a humidifier without a 24 VAC IN terminal?

The instructions for the humidifier I'm installing says to connect the humidistat wiring to the two terminals "marked 24 VAC IN". My furnace doesn't have terminals marked that. I have R,C,W,Y.G. Am ...
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173 views

Can I install a flow through humidifier on either side of the duct?

I was about to install a Wait6000 whole home humidifier when I hit this snag in the plan. On page 3 of their manual (PDF), it says the cold air return duct must be at least 10" wide. The diagram ...
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4k views

How can I figure out why the low voltage furnace fuse blows on heat but not cool?

I have a Tempstar Model NTC6100KFG1 gas furnace. Furnace was working fine through the summer blowing the AC. It's been off for a month or two as we've been changing seasons here. When I went to turn ...
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14k views

What size breaker and wire do I need for central air conditioning?

I am getting ready to hang drywall in my basement but before I do that, I need to run wire from the main panel upstairs to the future location of the central AC furnace through the basement ceiling ...
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16k views

How do I identify the C terminal on my HVAC?

How do I identify the C terminal on an HVAC, furnace, or boiler? If the terminals don't have a screw labeled C what should I look for on the wiring diagram? What steps should I take if a wiring ...
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297 views

How do I close this hole in the HVAC vent?

What's the best way to close up this hole in the venting leaving the hvac? Would foil tape be sufficient? Right now it bleeds out hot air into the basement in the winter, and cold air in the summer. ...
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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. ...
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1answer
4k views

Why does my pilot light go out when I release the pilot light knob?

My furnace pilot light will not stay lit. I can light it and depress the pilot switch for 2 minutes. But, once I let go of the button, the pilot immediately goes out. Does my thermocouple need ...
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776 views

Why doesn't my gas furnace ignite?

I had a Lennox slp98dfv installed last year - it has a surelight ignition - it now just blows cold air - so I assume the pilot light is out - but not sure how to light it - as u cannot manually ignite ...
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lennox furnace not working pilot light on but burner doesn't start

lennox furnace, model # G20Q2E-75-C1, serial #6392H32332, pilot light lights, blower motor turns on, burner doesn't burn
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Furnace won't adjust to thermostat setting

I have a 2007 Trane furnace that has been working the AC all summer just fine. With the cooler weather, when I turn on the heat and set the thermostat to 72 degrees, the furnace comes on but heats the ...
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6k 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
538 views

How do I maintain an 80% efficient natural gas furnace?

I have an 80% efficient gas furnace at my house, that is seemingly working well and is configured with an air conditioner. What preventative maintenance should be done to it, and at what interval? Is ...
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1k views

Can I remove the fresh air supply that is attached next to my furnace?

It looks like my gas furnace is already vented but I'm not sure. There are two white pipes from the top of the furnace that are vented outside. The furnace is a Trane XR90. We have cold winter climate ...
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577 views

What is this name of this vent attachment next to my furnace?

What is the name of this silver vent attachment thing at the bottom of the picture? It is attached to the side of our gas furnace. The black part is an insulated air duct which goes to a vent ...
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200 views

Should I use a quick or gradual 90 in my flexible A/C ductwork?

To elaborate a bit more. If you are running an 8" duct off the supply, would you do a quick 90 degree towards the destination or do a gradual 90 degree? I would guess a quick would be better because ...
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230 views

Replacing Oil Furnace with Heat Pump

My wife and I would like to remove the older oil heat from our home and replace it with a heat pump. We currently have an Amana central air conditioning unit (3 ton), and an oil furnace in the ...
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1k views

Why is the circuit breaker for my furnace stuck in the off position?

The breaker for my furnace is stuck in the off position. We were away for the winter and had someone shut it off, and now the breaker won't turn on at all. We shut off the thermostat upstairs thinking ...
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352 views

What is a quieter alternative to gas forced air heating?

My small 1BR apartment has an old gas furnace that works great, but costs my landlord too much to insure. He plans to install gas forced air, an in-unit upright furnace. I'd love to suggest a ...
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800 views

How is a high altitude natural gas burner different?

What is the difference between high altitude natural gas burner and conventional low altitude gas burner and why high altitude natural gas burner are needed?
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Why is water collecting in the base of my furnace?

I changed my filter the other day and noticed a pool of water in the bottom of the furnace, below the filter. The humidifier has been off so that's not the issue. I removed the furnace panels and see ...
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133 views

Can a non-expandable filter be used in place of an EZ flex furnace filter?

My Carrier furnace has the EZ flex filters (16x25x5). These come with the plastic end caps that fit on the expandable filters. Can a regular filter, non expandable, of the same dimensions be used as ...
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373 views

How do I interpret my furnace clearance diagram?

My brother-in-law and I are going to be finishing my basement. We just got the permit from the building inspector. When they returned my plans there was a note that told me to make sure furnace and ...
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119 views

What to look for in a new furnace

I've recently been told that my furnace, which is about 20 years old, is on it's last stretch and that I should consider replacing it now rather than waiting for it to fail - potentially at a very ...
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27k views

Why is my gas furnace now continually just blowing out cold air?

I had my heat set to 70°F all day and my gas furnace was blowing out warm air. Then out of nowhere, it started blowing out cold air for the past 3 hours. I tried turning off the furnace and ...
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16k views

What does a Summer/Winter switch on furnace air ducts do?

On some of our furnace ducts, there is a switch/valve for Summer/Winter or S/W. What does changing this switch/lever accomplish? Can bad things happen if I forget to switch it? Bonus question: ...
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15k views

If I turn off the breaker to the Gas furnace will the pilot light go out?

I need to turn off the breaker for the furnace but am afraid this will turn off the pilot light to my gas furnace & I don't know how to relight it. Are any special steps necessary to prevent ...
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1answer
489 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 ...
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1answer
726 views

How can I unbend a bent furnace filter slot?

I recently bought a new home. When going to change the furnace filter, I couldn't get the original furnace filter out of the slot at the last part of the filter (where the cardboard border is). Since ...
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2answers
541 views

Can I move my furnace room ventilation intake closer to my furnace?

I live in a 3 story townhouse with a garage in the basement. Off the side of the garage is our furnace room. The ventilation and exhaust for the furnace goes to the roof. For ventilation (air coming ...
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1k views

Why is my furnace blower coming on so early in the ignition process?

Alright, I installed a new furnace a few months ago and have begun to notice an issue with the blowers. When the furnace first starts up, the exhaust blower should turn on to expel gas, then the ...
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288 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 ...
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1k views

How can I stop my boiler from making all this noise?

I'd like to preface this post with the fact that I'm a complete diy amateur. I may say stupid things, or things that make no sense. Please feel free to correct me as I'm always open to learn. So, ...
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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. ...