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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10
votes
2answers
92k 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 ...
4
votes
2answers
12k views

Can I use the T terminal in my furnace as the C for a Wifi Thermostat?

I've read many posts on this, and believe I know what to do, but want to make sure. My furnace (a Lennox G14 Series) does not have a C terminal which needs to be connected to the C terminal in my new ...
6
votes
1answer
26k views

How many wires can be connected to the C terminal at the furnace?

I'd like install a new Wi-Fi thermostat. The old one didn't have a C-wire but luckily there is an unused wire on both sides (one coming out of the wall and one at the furnace not connected yet), so I ...
5
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7answers
8k views

How to Lower the Ouptut of Oversized Furnace

Questions I would like to lower the output capacity of my furnace if possible. How can I do this? Is it worth doing, or should I just live with it? Is there an easy way? Some ideas: replace burner ...
4
votes
5answers
154k views

Why does my pilot light keep going out?

My furnace pilot light keeps going out so I changed the thermocouple. Now the furnace will come on and heat up to the degree set on my thermostat, then the pilot light will go out and the furnace will ...
2
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2answers
8k 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 ...
18
votes
10answers
29k 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 ...
4
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5answers
44k views

Adding a C wire to a new Honeywell WIfi Thermostat

I am trying to install a new Honeywell touchscreen WIFI thermostat and need to add a C wire to my terminal inside the furnace (using the help found at How can I add a "C" wire to my ...
7
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6answers
126k 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. However,...
6
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2answers
3k views

Can an electric dryer be next to the gas furnace?

I intend to relocate my washing machine and electric dryer within the basement. The dryer will then be about 2 feet from the furnace. Is that OK?
0
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4answers
1k views

Is it safe to use an HVAC system even though the duct wrap contains asbestos?

In our rental house the furnace ducts are very dirty. We brought an expert to clean it, but he said he just won't do it because the tape around the ducts (in the attic) is probably asbestos. After ...
10
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8answers
5k 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 ...
8
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3answers
2k 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 ...
8
votes
7answers
112k views

How much energy will continuously running a furnace fan use?

We have a bi-level (tri-level? There's a small entry way and utility room, then an upstairs living area and master bedroom and a downstairs living area with bedrooms) in mid-Michigan. The downstairs ...
5
votes
2answers
8k 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 ...
4
votes
5answers
58k 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
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3answers
24k views

Why is my furnace blowing cold air?

My HEIL 7000 natural gas furnace has stopped working what are the most likely causes, and how to verify faulty parts? Normal operation routine Thermostat sends "need heat" signal. Exhaust blower ...
2
votes
0answers
54 views

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, ...
2
votes
1answer
3k views

Where to connect c wire in furnace

I have 5 wires running to the thermostat from the furnace. The blue wire is not connected on either side. I'd like to connect it as my c wire for a smart thermostat. On the furnace I see W R Y G and ...
6
votes
6answers
14k views

How often should the air filter in the furnace be changed?

Does the period of change of this air filter have an affect on the longevity of the heating and a/c system? What is a good rule of thumb to require replacement?
5
votes
3answers
10k 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 ...
4
votes
2answers
184 views

How do you calculate the right size furnace to maximize efficiency?

Given that sizing of the equipment is the most important issue to get right to maximize efficiency, what are the factors an installer should take into account to determine the correct size? Is it ...
4
votes
1answer
2k views

How bad is it to attach a gas water heater to a gas furnace electrical circuit?

I'm looking to replace my existing water heater with a more efficient model. One of the things that makes better models more efficient is the replacement of the thermocouple / pilot control system ...
4
votes
2answers
23k views

Why won't my furnace turn off?

My furnace is running OK and heating the house. The problem is that I have the thermostat set to 66°F and it does not turn off when it reaches that temperature. I can turn it off manually at the ...
4
votes
7answers
9k views

What should I do with old furnace filters? [closed]

I seem to be stock piling used furnace filters, are there any uses for these things once the furnace is done with them? It seems a shame to throw them out; given that I change them once a month, ...
3
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2answers
4k views

Can I piggyback a thermostat with a C Wire hookup on a furnace?

I'm trying to install a new thermostat that needs a C wire hookup. There are currently 4 wires running from the thermostat to the furnace, none of them are a c wire. When I look at my furnace itself ...
3
votes
1answer
744 views

How well would a hydronic furnace work with a gas tankless water heater?

My current heating system (in Ontario) is an oil hot water tank in a closed loop with a hydronic forced-air furnace (Enerzone XAH 68). The water circulates through what is basically a heat exchanger ...
3
votes
1answer
764 views

Timer for house ventilation switch - high/low voltage wiring

I have a home ventilation switch that I would like to wire a timer to. This switch is located in my upstairs hallway, and when flipped it turns on the furnace fan blower and the main bathroom exhaust ...
2
votes
1answer
11k 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 ...
2
votes
3answers
7k views

Furnace runs for about 5-minutes only and shuts off

Furnace (Lennox G40UH, 12 years old) runs for about 5-minutes (sometimes as high as 7-minutes) and they turns off despite the heating call from the thermostat continuing. Flame sensor has been ...
2
votes
4answers
29k 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 ...
2
votes
1answer
398 views

What is wrong with my gas furnace?

Note: the below was solved. It was a loose wire between the controller and the gas valve (the white wire on the diagram) This is about an old UltraMax Olsen HCS2 81AD gas furnace it looks like this ...
2
votes
3answers
5k views

Where's the C terminal on my boiler control?

The new thermostat I purchased doesn't run on batteries, and needs 24 volt power. I have only a red and a white wire connected between the boiler and the thermostat, but there is also a third, unused ...
2
votes
1answer
7k views

Ecobee3 not turning on heat, but fan is on

I have an Ecobee3 that has been successfully working (both heat, fan, and AC) for the past 6 months. Recently I was trying to get my humidifier working so I was playing around with some wires, which ...
2
votes
2answers
2k views

Is it safe to replace a Furnace pressure switch with a different one?

So I had some problem with my gas furnace and a technician came by to install a new one but it doesn't have the same rating and only has one tube instead of two. He assures me it's fine but I thought ...
1
vote
1answer
910 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 ...
1
vote
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 ...
1
vote
2answers
956 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
1answer
35 views

New primary control switch problems

About a week ago , I had someone to come in and replace my old RA116 stack switch with a Honeywell R8184G oil primary , for the first day it was fine, next thing I know the furnace turned off and ...
1
vote
4answers
32k 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 ...
0
votes
1answer
8k 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.
0
votes
1answer
106 views

Furnace installation: What separates the good from the bad? [closed]

This page says, Poor installation can reduce [a high-performance furnace] to a mediocre furnace Conversely, asm-air writes, Remember, who installs your HVAC unit is more important than what ...
0
votes
3answers
400 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 ...
0
votes
1answer
87 views

Is my furnace leaking water?

I have water accumulated in my basement, that I squeezed out using towel. It was about 8 gallons of water in all. The only source I can see is the furnace whose surrounding is wet but I have never ...