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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6
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3answers
7k views

Do I need a rain\snow cover on this furnace vent?

Just bought a house that had a new furnace installed this summer. Vent number 1 in the image is for the furnace (2 is the water heater and 3 is sump). As you can see in the image, 2 and 3 both would ...
5
votes
2answers
40k views

Which way does air flow into a furnace?

Which way does air typically flow in a furnace? Put another way, does the filter usually sit before the incoming cool air reaches the burners or after? I'm trying to figure out which way the air flow ...
2
votes
1answer
290 views

What could cause the furnace blower to come on constantly and no fire in gas burner?

When thermostat is turned up on my hot air furnace, the blower immediately comes on, blowing no heat, had it checked and with some luck the burner fired after about 10 tries of switching on and off. ...
3
votes
2answers
168 views

Can a furnace with a variable speed blower be used in a multistory house?

I just had an HVAC guy out to give me an estimate on a new Carrier Infinity series furnace and he said the second floor rooms will always be colder because the thermostat is on the first floor and not ...
2
votes
1answer
360 views

Could a high limit switch cause the furnace blower to run continuously?

My furnace was running fine. The I noticed that the unit was blowing cold air. Checked the furnace burners and they were off. I turned off the unit on the thermostat and the blower continued to run. ...
0
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0answers
76 views

ComfortMaker GUH075 series high-efficiency (93%) furnace isn't making heat

It worked a couple of days ago but today the fan blows but the burner doesn't seem to come on. The status indicator inside the access panel flashes four times but I can't find any reference to tell ...
2
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2answers
676 views

Furnace Draft Inducer Repair: is previously installed back plate necessary?

I'm replacing a non-functioning draft inducer on the Goodman furnace in my house (GMP075-3). The previous inducer was mounted with a sheet metal back plate between it and the wall of the furnace. ...
0
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0answers
64 views

Options for humidifier

Winter is approaching and the cool weather is making the air dry in our home. We're using room humidifiers but want to install a humidifier which can go on our furnace. However, we have very limited ...
2
votes
1answer
5k views

Why won't my Heil 7000 natural gas furnace ignite?

I have a Heil 7000 gas furnace Model: NUGK100DH12 Serial: L933050100 When we turn it on at the thermostat, the exhaust blower will kick on. We checked to be sure the gas is reaching the unit and ...
0
votes
1answer
140 views

What could cause a mobile home furnace not to light?

Our furnace won't lite. Mobile home pre 80. There is no name that we can see. The pilot light piece looks to be changed. Pilot light won't light. We don't hear or smell gas. It has settings last, 2, ...
5
votes
3answers
5k views

How can I avoid cold rooms due to combustion air intake?

I have a newer split level house (2006) with unfinished basement. The natural gas furnace is on the lower level in a utility room that is also laundry and bathroom. There's an enormous 8 or 10" pipe ...
0
votes
1answer
4k 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 ...
2
votes
1answer
176 views

How do I determine/control which heat source is used (heat pump, oil)

I have a heat pump and an oil furnace for backup. How does the HVAC system know when to use the heat pump and when to use the oil furnace? Specifics: I have a Honeywell TH8320U1008 thermostat ...
0
votes
1answer
697 views

Which terminal should be used for a ā€œCā€ wire when none are labeled ā€œCā€? Older electric furnace/heat pump

I have an all electric air handler/furnace connected to a separate AC unit and it is also a heat pump. I've purchased the latest and greatest Honeywell WiFi "Smart" Thermostat and it needs a C wire. ...
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0answers
272 views

Furnace not working properly with digital thermostat

I have been attempting to use several different types of digital thermostats to replace my old mercury thermostat, however none of them are able to control the furnace properly. All of them are able ...
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0answers
79 views

Furnace reset problem

I have a new Goodman high efficient furnace model number GMH950703BXAG1. And this is the problem I'm having now: Turn on the furnace power (after ~1 hour off) Turn on the thermostat with Temp ...
0
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0answers
75 views

Steps for annual maintenance on a fuel oil furnace?

We have fuel oil and this year I'd like to try and maintenance the furnace myself: By "maintenance" I mean "clean it up so that it runs well throughout the winter." Just a basic tuneup and ...
0
votes
0answers
94 views

Which should I do first? replacing furnace or resurfacing concrete floor?

I'm going to get two things done in my basement soon (by hiring professionals), but I'm wondering what the right order of operations is. One task is to replace the gas furnace that sits near the ...
8
votes
2answers
805 views

Why are furnace/central AC blowers so inefficient?

I can buy a ceiling fan from Home Depot capable of moving 5,000 CFM of air for about $50, and it uses a mere 50-60 watts while doing it. By contrast, most furnaces seem to have blowers that operate in ...
2
votes
1answer
178 views

Is it a problem that I have two of each color wires on my Honeywell thermostat?

I am thinking about upgrading my Honeywell thermostat. Every thing I have seen describes / shows a single wire for each color. My current thermostat has two wires connected to each terminal (two green ...
4
votes
3answers
4k views

Why does the pilot light go out when the furnace is running?

Every time the furnace fires up, it blows out the pilot light. Sometimes it will run a full cycle and blow out when it shuts down, and sometimes it will blow out about a minute into the cycle. We ...
2
votes
2answers
441 views

Are High End Furnace Filters worth the cost?

There are many levels of furnace filters. I can get cheap ones at walmart of a few bucks. Then there are ones that cost upwards of $30. I realize that if you have allergies or low immune systems, ...
4
votes
1answer
3k views

What would cause my furnace to only work with the filter removed?

My Carrier furnace works fine without the air filter in place on the return. With the filter in place it works for a while and then stops with a complaint about "limit, or flame rollout is open" ...
3
votes
2answers
5k views

What would cause a furnace to shut off prematurely?

I've got a Carrier Weathermaker 8000 furnace that shuts off about 90 seconds or so after ignition, started doing this recently. I get flashing code "33" which indicates: The code indicates: 33 ...
3
votes
2answers
620 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 ...
2
votes
1answer
5k 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 ...
0
votes
1answer
84 views

Would a radiant barrier help stop this heat transfer?

Using my nifty thermal camera, I discovered that my furnace closet's combustion air duct (visible in this question) is getting really hot when the attic heats up, and then (being sheet metal) it ...
1
vote
1answer
195 views

Why does my Thermo Pride oil furnace need constant restarts?

We have a Thermo Pride oil furnace that requires frequent restarts to run. We just purchased the house and had the annual service/safety check completed as it was neglected for several years. When the ...
0
votes
1answer
226 views

Water has quit running thru my humidifier.

Furnace humidifier dry as a bone. have changed the filter, duh, that is the only thing I know how to do! Bottom line, there is no water running through it.
2
votes
1answer
419 views

Can I properly install Roxul mineral wool batts in a mostly-drywalled stud bay by pushing them up from below?

Using my nifty thermal camera, I discovered that my furnace closet's combustion air duct (visible in this question) is getting really hot when the attic heats up, and then (being sheet metal) it ...
8
votes
2answers
1k views

Should I insulate steam pipes in the basement?

I have a steam-radiator heating system. The furnace is in the (unfinished) basement, and the steam-carrying steel pipes spread out across the basement ceiling before going up into the rest of the ...
0
votes
3answers
29 views

Can't select some temperatures with the thermostat of my furnace

I have a problem with the thermostat of my furnace. This problem is wired but I'll try to explain it as clearly as possible. When I turn the button of the thermostat, some temperatures can't be ...
2
votes
2answers
349 views

What could be causing my gas furnace to make a loud noise?

I have a comfort air natural gas furnace when it call for heat,their is a loud boom noise,could the hot surface ignitor have a crack or needs replacing?
1
vote
2answers
175 views

How can I safely put a plug on an old furnace motor that has just two wires

My Old furnace motor has just 2 wires, Black and white. How can I safely put a plug on it to use it? I want it to power a chicken plucker.
2
votes
2answers
3k views

Should my furnace closet have this huge duct opening into the unconditioned vented attic?

So my interior furnace closet has a huge duct in it that connects the closet to the unconditioned vented attic right above it. Needless to say, this is a huge air leak into the conditioned part of the ...
1
vote
0answers
161 views

How can I install a furnace register in a kitchen-cabinet toe kick?

I'm planning to install new kitchen cabinets. I'll be covering up the kitchen's existing sidewall diffuser with new cabinets, so I'd like to relocate it to a new register in the toe kick of the sink ...
0
votes
1answer
628 views

I have just reset furnace due to a trouble code, what should I monitor or re-do over the next few days?

My furnace was throwing a trouble code. The code was 31 and for my manufacturer (Bryant) and others thats is a pressure switch code. I was able to resolve this code and get my heat back on simply by ...
0
votes
1answer
205 views

How can I prevent my furnace exhaust pipe from freezing?

My furnace keeps on turning off because my air intake freezes. The reason it freezes up is because my neighbors exhaust vent blows directly on it. What can I do to prevent this?
0
votes
2answers
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 ...
2
votes
1answer
7k views

Which way does the air flow through my furnace?

Below is my furnace and I need to change the filter however I am unsure which way is the airflow direction. Red or Blue?
0
votes
1answer
58 views

Furace fuse blows when Aprilaire humdifier is turned on above 35%

I live in a pretty old house and have a Carrier furnace with an Aprilaire humidifier attached to it. The device that controls the water flow, I guess it's a solenoid, is visible on the exterior of ...
2
votes
1answer
216 views

Is my Heat pump and gas furnace installation incorrect?

I moved into a house about 2.5 years ago, and the previous owners had a heat pump installed, together with a gas furnace. Recently I had my furnace repaired (faulty igniter) and the HVAC technician ...
2
votes
1answer
461 views

Is the furnace undersized?

I have a 2700 sq ft rambler home with cathedral ceilings over a large portion of it - over the hallway, 2 living rooms and kitchen. We replaced the furnace that was installed when the home was built ...
0
votes
1answer
310 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 ...
0
votes
0answers
125 views

Why does my furnace make sounds like a tuba when kicking on?

I have a 21 yr old Bryant furnace. Recently it started making a horrible noise when the heat first kicks on. It sounds like someone playing the tuba. It only lasts a few seconds, but it's loud ...
1
vote
1answer
259 views

What to do first in a house with poor thermal performance and high energy bills

I just moved into a house and am a little bit disappointed in its thermal performance so far. It's winter and cold outside, and the furnace heats the house up pretty quickly, but then the house gets ...
0
votes
1answer
136 views

What is this pipe - should I be worried?

We found it behind a wall, it is a bit more than 10 inches wide it has about an 3/4 inch of concrete between metal. It was jaggedly broke off on the bottom in the basement ceiling. It is also ...
0
votes
1answer
333 views

Furnace keeps resetting

My trane xr90 furnace keeps resetting just while it is in its "heat up phase" I'm a laymen but a description of what is happening is like this... The furnace gets a call for heat, it makes a sound ...
0
votes
1answer
237 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 ...
1
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0answers
122 views

Why won't a NEST that shares control of a furnace with a conventional thermostat turn on the heat?

I have three floors in my home. The bottom floor has its own gas furnace and the 2nd and 3rd floors share another gas furnace. Everything was working great until I added a NEST to the first and ...