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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8
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8answers
3k views

How can I audit my furnace?

I want to keep track of when my furnace is on, with an eye to reducing how much energy I use to heat my house. I could compare it with weather data (temperature, wind speed, precipitation). I could ...
0
votes
2answers
761 views

Wiggle, wiggle, wiggle wires on Furnace Pressure Switch makes it work — should I replace Switch?

My Furnace (a Rheem Criterion II Gas Furnace - model RGLH-07EAMGR) has had a problem for a while that we've just been living with but I can finally afford to do something about it. What happens is ...
0
votes
2answers
511 views

Why does my oil-furnace's on-demand water heater go tepid and then return to full heat?

We have an issue with the hot water from a 2004 Peerless oil furnace with on-demand hot water. The shower starts at full temp, but quickly goes tepid (too cool for a bath/shower, but not ice-cold) and ...
2
votes
0answers
18 views

Why would my Maytag FG6RC high efficiency furnace restart in the middle of a heating cycle?

My furnace is probably 7-8 years old, and this heating season the furnace has developed a strange problem. The furnace starts normally, but before the temperature reaches the thermostat setting the ...
1
vote
0answers
14 views

Why won't my furnace turn off after replacing the igniter?

My igniter on my Frigidaire furnace went out. before replacing it I reset a limit switch that set off. I changed the ignitor and everything works, however now the thermostat is not shutting it down at ...
0
votes
1answer
244 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 ...
1
vote
2answers
86 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 ...
0
votes
1answer
353 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 ...
14
votes
10answers
16k 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 ...
6
votes
3answers
104 views

How can I prevent my furnace and A/C from slamming doors?

What specifics will I need to collect to figure out if our furnace and A/C are sucking too much at the source/intake? I don't know the proper terminology for these things, do forgive me for any ...
1
vote
1answer
31 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 ...
-4
votes
1answer
57 views

how do you manually turn on the gas to your house?

During an account switch our gas got turned off. The account is straight now but national grid goes on coffee break from 12am sat till 7am monday and for us, enough is enough. 3 family 3 story ...
1
vote
2answers
207 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
17 views

Goodman GM100 Failure to recycle

Our Goodman Furnace Model GM100 Serial# 9412063230 will start up and run but will not recycle after initially satisfying the thermostat. If you wiggle the gray,(ground), wire on the gas valve, it ...
0
votes
0answers
8 views

Goodman GM100 fails to recycle [duplicate]

Our Gm 100 Furnace fails occasionally to recycle after working fot a while. I have determined that something is becoming disconnected in the black terminal "box" on the gas valve. If I move the gray ...
0
votes
1answer
36 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
111 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 ...
3
votes
3answers
23k views

How to wire multiple thermostats

I would like to have two thermostats controlling a single furnace. However I'm not 100% sure how I would need to wire everything to achieve the correct effect. Assuming a thermostat simply acts like ...
1
vote
2answers
26 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. ...
0
votes
3answers
1k views

Why does my furnace drip bucket fill up so frequently?

We have an oil furnace that heats the house using a two-zone hot-water circuit, and also acts as an on-demand hot water heater. There is a pipe coming off the collection of pipes coming out of it that ...
2
votes
2answers
38k views

Why does my pilot light keep going out?

My furnace pilot light keeps going out so I changed the thermalcoupler now the furnace will come on and heat up to the degree set on my thermostat, then the pilot goes out and the furnace will not ...
0
votes
0answers
25 views

What should I do if both the diagnostic LEDs are off on a Lennox G40UH(x)series heater control board?

My Ignition control Board on the G40UH(x)series both of the diagnostic LED's lights both are off, any suggestions in how to resolve this problem
0
votes
1answer
213 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) ...
7
votes
1answer
97 views

Decrease dust in an old house, forced air

My house was built in 1940. I have noticed the forced air pushes out a lot of dust. This is evident from lint collecting on the bathroom vanity below a vent. It only collects lint during Summer and ...
1
vote
1answer
57 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 ...
4
votes
1answer
53 views

Will heat set off a smoke detector placed in an attic?

A heating furnace is in a partially floored attic. used for storage only We have placed a smoke detector above the furnace and wonder if the heat in the summer would set it off.
0
votes
1answer
105 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 ...
1
vote
0answers
20 views

Why does my furnace only heat up to a certain temperature?

Why does my furnace only heat up to a certain temperature, then it stops heating the home? My programmable thermostat is set to go up to 70 degrees (to heat the home) and for some reason when it ...
1
vote
1answer
78 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
0answers
15 views

Can a full expansion tank prevent the furnace from going on?

Woke up this morning and the furnace wasn't working. The furnace is relatively new, and there appears to be a small amount of water dripping from the top of the expansion tank. I know that the ...
1
vote
1answer
357 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 ...
1
vote
2answers
269 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 ...
2
votes
1answer
42 views

furnace question

I have a tenant that constantly sets the thermostat at 90 degrees for the heat. I have told her several times to stop because she will burn the unit up. What are the consequences of this and how long ...
0
votes
3answers
69 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 ...
1
vote
1answer
218 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 ...
-2
votes
1answer
55 views

Should I Expect Reimbursement for a 2 Year Old Furnace? [closed]

I'm having an addition put onto my home and it is significant enough to warrant a larger furnace. Unfortunately, I recently had to replace my furnace. It is a two years old Trane brand furnace, two ...
2
votes
1answer
322 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 ...
0
votes
2answers
66 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 ...
1
vote
0answers
21 views

Replaced Thermostat, Furnace worked for 1 cycle now blows cold

Hello I just replaced my old White-Rodgers thermostat because it just wasn't working consistently (sometimes it would turn on the furnace, but mostly it wouldn't). I swapped it with a White-Rodgers ...
1
vote
0answers
26 views

Why won't my my furnace stop running unless I shut it off at the breaker?

I can't get my furnace to shut down unless I turn off the breaker. Why is this happening, and how do I fix it?
1
vote
1answer
542 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 ...
0
votes
1answer
16 views

Amana Furnace 90% eff. need help

Furnace will run for half a day to a day producing heat, then it will stop producing heat but the furnace will try to run still blowing air. Also, if I flip the switch off and then back on 10 seconds ...
0
votes
0answers
27 views

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 ...
4
votes
4answers
6k 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 ...
3
votes
2answers
82 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 ...
1
vote
1answer
3k 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 ...
0
votes
2answers
33 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 ...
5
votes
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 ...
1
vote
0answers
29 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 ...
3
votes
6answers
26k 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. ...