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Questions tagged [furnace]

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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Lennox Furnace Blower not working on AC In On or Auto

Please Help! I have a Lennox Furnace Model G60uhv(X) after years of working fine I switched the thermostat to AC and it failed to start the cooling cycle. I suspect some sort of problem with the ...
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Line to AC dripping at the furnace

My line from my exterior AC unit is dripping at the furnace. The dripping over time has caused rusting and we've had to replace the control board under it. It appears the root cause of the problem ...
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Furnace Connect G Wire

I have a dual energy electric/oil furnace that is wired to a thermostat with 2 wires R and W. I don't have any AC. Inside the furnace there is a switch relay to control the fan but it is not connected ...
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I have an unused C wire hooked up to thermostat and have no idea where to connect it to the furnace for power

I know this question gets asked all the time but I've spent hours staring at forums as well as my furnace and at this point I'm desperate. I just bought a nest thermostat that needs a C wire ...
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HVAC blower fan won't stop

FINAL UPDATE: I have found the culprit - the Nest thermostat itself. First, I disconnected the t'stat at the control panel and found out that the fan would no longer start upon powering the system. ...
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1answer
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Need to identify wires coming from external AC Unit

idiot DIY'er here :P. I recently installed a smart thermostat and long story short; I removed the two wires from my furnace's board for the external air conditioning unit in the process. I was going ...
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1answer
79 views

Exhaust Fan Runs With No Power at All!

How can my furnace exhaust fan run with the power off, the thermostat off, and the breaker off?!
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1answer
39 views

Furnace with no “C” connection

I have a mobile home furnace. This furnace only has a 4 wire connection terminal, G,W,R,Y. I also have a condensing unit outside with the 24 volt 2 wires coming to the furnace. I know I connect one to ...
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Furnace Pilot Flame ON constant but Main Burner never kicks in

I own an older furnace (Armstrong EG6F80DC12-6 -- natural gas, forced air, single stage, Honeywell S8600C Continuous Re-Try Module, VR8204A Gas Valve w/ Pilot Burner / Igniter-Sensor). It has been ...
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Lennox Furnace Troubleshoot Assist

I have a Lennox Elite G50UH-24A-070-15. It quit entirely and threw the error "Pressure Switch open or blocked" according to the diagnostics panel on the front. Recent renos so thought it was clogged/...
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Why is there a minimum distance to a corner from a direct vent exhaust?

According to the instructions for my direct vent furnace, (item #4) the minimum distance from the center of the vent to the nearest corner is 16 inches. Why is that important? I understand the ...
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1answer
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Furnace Pressure Switch Testing

I have a ComfortMaker combination furnace/AC for the back part of my house. The furnace kicks in, but never heats up. No errors are reported. Started troubleshooting and took a peek at the pressure ...
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positive pressure in a furnace room

I am planning to install an insulated exterior grade door on a finished furnace room in my basement. The room will have a hot air supply register but i read that I cannot put in a return because i ...
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1answer
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What is the right way to extend a furnace intake pipe under a brick patio?

Our gas furnace intake (one of them, there are other intakes inside the house) currently comes out the side of the house but under a brick patio. It seems that the previous owner of the house extended ...
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Furnace heat satisfied but inducer starts and ingnition tries over and over

I have a Heil furnace 90 plus mfg 1989, Heat cycle is satisfied and thermostat is not calling for heat. Induced draft motor starts, spark igniter starts, blower starts and runs like this for 3-4 ...
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1answer
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Trane XV80 furnace, two wire setup, wanting continuous fan when no heat is needed

I found the "Why doesn't the “fan on” mode work after I installed a new thermostat?" thread on this site and am wondering if the manual rewire steps would also work for a two wire system. The setup: ...
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2answers
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No C terminal on furnace to connect a wifi thermostat

I have an new Emerson thermostat and would like to connect a c wire so it always has power. I have an extra wire that's not being used, but I don't have a C wire terminal on my furnace. I'm wondering ...
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2answers
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Pilot light keeps going out

I have a Coleman mobile home furnace and my pilot light keeps going out. I have replaced the thermocouple twice, cleaned the orfice, replace the gas regulator with a brand new one, and even crawled ...
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I have a bryant air handler where the power to thermostat is lost

I have replaced thermostat with a new one, changed the circuit board out twice due to wasn't getting power to thermostat. when I power up after wiring in connections. fan comes on for a moment along ...
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1answer
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Adding split AC to a Dayton oil fired forced hot air furnace

I'm trying to add split central air to my Dayton oil fired forced hot air furnace, mod # 3E268A. The manual clearly says it can accept this but the terminal block in the unit only has (4) lugs. TT and ...
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1answer
53 views

How to troubleshoot gas supply not making it to some appliances

I recently purchased a home and once utilities were turned on I've been having issues with certain gas appliances. Some appliances required a normal amount of time to get the gas flowing after being ...
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2answers
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Using existing exhaust stack for new furnace

I'm about to replace the furnace in our house. The existing furnace uses a 6" stack through the roof. I know most new furnace installations just use PVC and poke out of the wall at about ground level. ...
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1answer
42 views

Unable to locate filter on Gas Furnace

Can not find where the filter for this furnace is. It is a gas Rheem Criterion II. Have watched YouTube videos but none look like mine. Thermostat keeps saying filter needs replacement.
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1answer
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What's the right size pipe to buy for gas supply for this furnace?

I'm trying to figure out the right pipe to buy for a direct vent wall furnace. The instructions show 3/8 inch npt, and also say that the gas inlet is 1/2 inch. When I measure the gas inlet it appears ...
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Does anyone know what this type of furnace/heater is called?

I have this old style of heating but I cannot find any information on it. Can anyone help? It's gas and just sorta gets hot heating the house. No blower, no ducts, just the exhaust. The brand on the ...
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1answer
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Furnace blower comes on full time when the thermostat is set to Auto

I have a Maytag furnace and the blower motor comes on right away when the thermostat is placed in auto and stays on when reaching the temperature set point and the heat goes off. I have replaced the ...
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Rheem 45,000 BTU gas furnace wiring- 1991 year

What are Rheem 45,000 BTU gas furnace wiring connections for the older hot surface control board? 1991 year model: rgde-04nhacr
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1answer
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Trane Furnace Fan Works, But Heater Won't Run

As stated, my heat isn't coming on. When this started: Everything has been all fine and dandy all winter. The other day I ran the fan only for a few hours without the heat. After this, my heat ...
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1answer
28 views

Furnace control board wiring - swapped on adaptor?

I am trying to replace my Goodman control panel (see this question), and have a wiring question. The new control panel (50M56U-843) that I acquired came with a large variety of wire adaptors. I ...
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1answer
51 views

Dropped item in furnace duct

While trying to stop the ticking noise coning from my furnace ducts, I accidentally dropped a small piece of fire retardant foam (as you can see in the below photos) in one of the vertical furnace ...
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1answer
32 views

Aquatherm - thermostat is dead. What to check?

(Thermostat: White-Rodgers 1F80-51 Heating Unit is aquatherm, XUAQ22-2, this is a heat exchanger hanging off a hot water heater, and giving us forced air heat for a 500 sqft space. Unit and ...
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23 views

Why doesn't my Goodman furnace make heat sometimes?

I have a 2.5 ton 2 stage Goodman furnace. It's about 5 years old. Problem is sometimes when I start it I can hear the blower start up but no heat just cold air. This is a intermittent problem ...
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How do I stop the ticking noise coming from my furnace duct? [duplicate]

I've had some HVAC people here to look at the ticking noise coming from our furnace duct. One of them installed a brace on the piece in question. This seemed to make the ticking less frequent, ...
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4answers
164 views

Connect two thermostats in parallel

I saw a thread about connecting two thermostats in parallel. I could not add comment to that thread , so I put question here again. My tenants always shut off thermostat or reduce temp when they are ...
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1answer
141 views

Where to attach the c-wire inside Goodman GMP100-4 Furnace

As a relatively new home-owner, I recently came across the whole C-wire issue for the first time, having had to recently replace an old thermostat, and there is no C-wire connected inside the furnace. ...
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2answers
54 views

Goodman furnace not lighting

After a few power outages and some very cold weather, the Goodman (GMSS960803BNAA) propane furnace at our cabin is not heating. The thermostat is new/replaced (Nest) and I've checked voltages for the ...
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1answer
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need to connect a c wire to my furnace/air conditioner

I installed a nest with 5 wires, but the blue wire is not connected to anything on the 25-30 year old furnace. We tried connecting the blue wire to what we thought was a common terminal, but the ...
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2answers
142 views

Are black marks on the wall over a radiator cause for concern?

I'm looking to purchase a home that has a hot water system. This home shows black marks above the radiators on the painted walls. What does this mean and should I be concerned? The previous owner ...
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Why isn't my furnace igniting?

I noticed cold air from my Carrier 58SS furnace. The main burners were not lighting. The pilot flame was strong, but yellow. When I tapped on the gas valve, the pilot shut off. I removed the pilot ...
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1answer
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How can I control my furnace fan from a secondary thermostat?

I have a WaterFurnace geothermal system with upper and lower level zones. I recently added an outdoor wood burner and my issue is that I want to use a secondary stat to run the furnace fan during the ...
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2answers
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What's wrong with my heater?

My heater only turns on if the temperature inside the home is 68 degrees or above. If the temperature inside the home is below 68 degrees, I can hear the thermostat click when I turn on the heater but ...
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1answer
55 views

Where is my furnace air filter?

We moved in to a house a few months ago and for the life of me I cannot find the air filter for the furnace anywhere. The furnace is a Payne brand. It's kind of old. In our hallway ceiling, we have ...
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1answer
87 views

Furnace blower motor starts but then starts clicking and eventually stops with a loud buzz

I have a Bryant furnace with a multi-speed blower. Yesterday I just replaced the capacitor and confirmed it is still working. The furnace turns on fine and the blower motor starts up when expected. ...
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1answer
45 views

Half of furnace turned off?

I moved into this house about 10 years ago, I noticed on the furnace that one of the breakers for the electric coils is off with a note saying "Leave breaker off". After cleaning out the blower for ...
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1answer
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Furnace not heating after changing thermostat

I have an ancient furnace/AC combo that came with my apartment that originally came with a very simple battery powered thermostat, which I replaced with a modern Honeywell programmable wifi thermostat....
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2answers
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Furnace continously shutting down due to lost or low flame sense (Rheem)

My furnace will run great for most of its cycle, but when it has almost reached the thermostat setting, I will hear it shut off, run the blower, then re-light. It will sometimes finally reach ...
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3answers
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Why won't my furnace complete the startup sequence when powered by a portable generator?

We recently had a power outage that lasted several days and the house was down to 41 degrees and expected power restore was several days in the future. I purchased a 3500 watt (5250 starting watts) ...
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Where on the board do you hook up a humidifier

I have a RUUD Ultra series furnace. I also have a generalair humidifier. Where on the furnace board do you hook up the humidifier leads? I see HUM STAT and HUM OUT Let me know. Cheers, KW
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Replacement draft inducer motor stopped working after 3 months

My Goodman GMNT060-3 furnace stopped turning on in October. The tech diagnosed a bad draft inducer motor, because the fan wouldn't spin freely and made a grinding noise when turned by hand. I replaced ...
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2answers
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Do I need a fan in my furnace room?

My furnace room is small and has a new gas furnace and water heater. I usually leave the door open to the laundry room. My garage is adjacent to a wall in the furnace room. I'm thinking of putting a 4 ...