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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The thermostat is set at 73 however the furnace doesnot kick on until it is down to 67.

The 96 % goodman furnace was just installed. The service man changed the thermostat but I think her switched some of the wires. When I have it set at 73 it does not kick on until the tempature is ...
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5k views

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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2answers
76 views

What is the smell coming through my HVAC system?

If I leave the furnace fan always running for an extended period of time (to circulate and filter the air), when the central AC turns on there is a not-so-fresh smell that is emitted through the ...
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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 ...
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2answers
32 views

train xl 80 unit fires up then shuts right off

i have a train xl80 furnace. When it calls for heat the draft inducer fan turns on and then the burner fires up for a short time then shuts off then it starts all over again.I am thinking its the ...
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3answers
2k views

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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25 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 ...
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1answer
208 views

Condensation running down pipe connecting furnace thru ceiling to chimney

I had a new downflow 80% efficient furnace installed in 2006. I don't use it regularly as I normally heat my home with my woodstove (separate chimney). But I have used this new furnace many times ...
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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 ...
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6answers
24k views

Why does my furnace need frequent power resets?

I have a NOMA Programmable thermostat attached to my furnace. The set point is usually around 21 degrees, and the room temperature is reading around 17 degrees. The furnace is not coming on. ...
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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
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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 ...
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2answers
62 views

Wiring Aprilaire 700 Humidifier to York TG9* Furnace

I've read the related posts, but they don't answer my questions. Please, help! We had contractors installed: * Aprilaire-700 Humidifier with Auto/Manual Humidistat-Control Knob (non-digital) * ...
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11 views

Furnace blower way to high, won't heat home properly [closed]

I have put cardboard over return grill, home heats great, so how long till I damage the motor?
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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 ...
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2answers
42 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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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?
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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 ...
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2answers
35 views

Can I remove a furnace compartment vent that's obstructing roof repair?

There are two vents going up to our roof, one is the normal vent from the furnace exhaust straight up to the roof. But right next to it there's a second vent pipe, a little larger and single wall. ...
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2answers
21 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
197 views

How can I replace an old dial thermostat on an oil furnace with Hydrostat 3250 Plus?

I recently bought a home with an oil fired Biasi furnace that has a Hydrostat 3250-Plus attached. It uses an old analog round dial thermostat, and I'd like to replace it with a new digital (wifi) ...
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9answers
15k views

Do thermostat-controlled, auto-adjust HVAC vents exist?

The residential forced-air HVAC systems I have seen are controlled by a single thermostat in one room. One has to manually adjust the vents in order to adjust the temperature in other rooms. Is ...
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2answers
51 views

HVAC system setup

I have a builder building me a home right now and we had agreed to set up two separate heating and cooling systems for the first floor and second floor of the house. I raised the issue the other day ...
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2answers
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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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 ...
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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.
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1answer
45 views

Can a gas furnace be installed in an outdoor enclosure?

I have an old home in which ductwork has been retrofitted. The ducts for the first floor are arranged under the floor. The first floor is heated and cooled by an electric package unit sitting just ...
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1answer
41 views

How to determine if my heating & cooling system is adequate for my home?

Is there some kind of calculation I can follow to determine if the heating and cooling system in my home is rated (adequate) for the size of the house? I assume there is some way to say something ...
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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 ...
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1answer
69 views

Can you vent electric dryer into furnace return?

I've got an electric dryer currently vented outside: Behind the door to the right is our heat pump furnace: I was thinking about, during the winter, venting the dryer (properly filtered for lint) ...
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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 ...
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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 ...
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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 ...
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2answers
37 views

How far should my wall be from my furnace/water heater?

) we are refinishing the basement and are enclosing the furnace/water heater, leaving a thin 27" door. My water heater sits back beside my furnace and the enclosure is going to be square so I think ...
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1answer
31 views

Why are my radiators leaking?

I have a gas boiler that seems to have way too much water in it and has pushed the excess water out the vents on my radiators. I have shut it off. It has flooded my main floor. How do I stop this?
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2answers
205 views

Could wind be causing my high efficiency furnace exhaust to back up into the house?

I am Toronto based, and just installed a new high efficiency furnace (York YP9C 080 model) in November. Later on I smell odor in my house when the heat started. It is more apparent when it is a gusty ...
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4answers
10k views

How do I wire an old furnace motor so I can use it as a garage exhaust fan?

Since last I posted, I moved WAY south (lil warm down here) and the house I moved into was a foreclosure so a few things needed done, namely the AC and furnace. When the guy did the job he said he ...
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3answers
56 views

Closing off heating ducts

We have a natural gas furnace that currently heats our entire 2400 square foot home. We plan on putting in a rental suite in the basement which will require closing up all the duct work into the suite ...
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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 ...
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1answer
264 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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2answers
65 views

What could cause the blower in my furnace to come on?

Ok my blower just turned on, my propane furnace and it's not in operation due it being summer. My thermostat is set at 65 and the room temp is 78. The heater never actually fired it was only the ...
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2answers
52 views

How do I reduce the noise from my forced air furnace?

We recently had a new forced air furnace and return installed. The unit works great, but the return (which is in an adjacent closet to the furnace closet) is quite loud. What are some solutions I can ...
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2answers
57 views

How do I calculate how long a furnace has to work to compensate a given temp drop?

I am trying to understand the dynamics of heating a home after the furnace size was calculated. Say you have a 60000BTU furnace to heat a 2000 sqft home. At the beginning of the heating season you ...
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1answer
56 views

Is it normal for the burner in my furnace to turn on and off during a single heating cycle?

During the heating time when the furnace is running to reach the temperature ask for, the burners will run for 3.5 to 4 mins.than shut off for 1 min. Then turn on again.it will do this until temp. is ...
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1answer
125 views

Will a single ductless mini-split heat pump be able to distribute its air evenly throughout my ranch house?

I am in the middle of a deep energy retrofit of my house, and a quick-and-dirty online manual J calculation of the projected loads once my projects are completed shows an estimated heating and cooling ...
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1answer
2k views

gas furnace pilot light is lit,,won't produce heat, making a clicking sound,,,

my gas furnace isn't producing heat the pilot light is on and it's making a clicking sound what can I do? I've tapped the flame rod.
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1answer
121 views

How do I connect my whole house humidifier to my furnace?

Connecting Desert spring Humidifier to the furnace: Do I eliminate the 24V transformer that came with it? The furnace Keeprite has the the electronic board says Humidifier W1 and C. where can I ...
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3answers
216 views

Running computers in basement storage room safely

I have kinda an odd one. I'm mostly concerned about fire safety here and am not concerned about power, I already know how to handle that properly. I have a somewhat large basement with an unfinished ...
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2answers
55k views

How can I test whether my furnace issue is the limit switch or the thermostat?

I suspected this issue during the winter and confirmed it now in the summer. Regardless of the temp in my home, the blower motor runs non-stop. In the winter this must have been causing my home to got ...
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1answer
393 views

how to change furnace filter (bottom return) for Lennox G43UF

I have a Lennox G43UF furnace and I am not sure if I need to have both a filter for a side return and bottom return. If I do (which sounds logical), where would the location of the bottom return ...