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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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 ...
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2answers
119 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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3answers
61 views

Will a high efficiency furnace vent etch the brick on my house?

My neighbour just informed me that they had to change the vent on their high efficiency furnace. The furnace vents between our two houses and it used to have an elbow on it directing it along the ...
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2answers
110 views

How to address loud cold air return

The cold air return on my forced air furnace is too loud. While it is is tolerable, there is a noticeable sound of rushing air when the furnace is running (not a whistling sound, just a blowing ...
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2answers
311 views

why does my gas furnace exhaust constantly

why does my high eff gas furnace exhaust run constantly ( when furnace isn't on ) the furnace turns on and off a few times before running then the blower comes on. now the exhaust wont stop without ...
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0answers
13 views

WiFi thermostat won't run. Not sure where to connect C wire [duplicate]

I just replaced a 2 wire thermostat with a wifi one that required a c wire. There was an unused blue wire which I attached to the C connector on the transformer at the furnace. At the thermostat, the ...
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2answers
4k views

Why doesn't the “fan on” mode work after I installed a new thermostat?

We moved into a new house. I installed a new Hunter Thermostat. I have a furnace only and the old thermostat only had 3 wires connected. SO I connected those three wires (G, RH and W/B). The ...
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23 views

Luxaire Acclimate 8V Series manual

where can I get/download: 1) USER’S INFORMATION, MAINTENANCE AND SERVICE MANUAL for Luxaire Acclimate 8V Series Furnace, Model Number FL8V080A12UH11, year 2005 and 2) Installation manual Please, ...
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20 views

Inductor motor doesn't shut off and overheats

I have a Intertherm/NORDYNE 75K BTU furnace. It's installed in a 2200sf home. I believe it's under-powered for a home this size. When there is a filter installed and the cover is on the furnace it ...
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2answers
877 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. ...
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4answers
86 views

Furnace Tries 2 or 3 times before staying on until reaching set temperature

I have noticed my furnace will cut the exhaust fan before lighting or sometimes start heating for a few minutes then stop. A few minutes later it tries again and will stay on until reaching the ...
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25 views

Gravity furnace won't turn off

Why would a gravity furnace not turn off? Tried disconnecting the thermostat and it still stayed on. Had to turn the gas off for the heat to stop.
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3answers
5k views

lennox furnace not working pilot light on but burner doesn't start

lennox furnace, model # G20Q2E-75-C1, serial #6392H32332, pilot light lights, blower motor turns on, burner doesn't burn
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42 views

Constant cold air from vents with new downdraft furnace

Replaced with newer, high efficiency furnace and cold air constantly coming out of vents (except when furnace running). It's like the downdraft is totally free flowing and when windy outside very ...
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20 views

Why does my kerosene furnace stop running?

I am having issues for months now with my kerosene furnace for a mobile home. It is a beckett relay and becket flame box. I have changed electrodes, I changed eye for flame sensor, the nozzle is not ...
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1answer
25 views

Central Furnace blower alwas on, even with thermostat disconected

A technician told me it was the electronic control board that has the blower relays on it , I replaced it and still has the problem, I've been reading here online about a limit switch for the blower ...
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6answers
40k views

Gas furnace kicks on then off frequently

A few times in the past week I will wake up to my furnace turning on, hearing a click when it tries to ignite, then turn off. This will happen for a couple minutes before the furnace quits trying. ...
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50 views

Where is this water coming from around my condensate pipe? (super confused)

Okay, so somewhat complicated story. When we bought our house 6 months ago the furnace was brand new but the AC unit was old. AC unit developed a leak that was expensive to repair, so we replaced it. ...
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5answers
134 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 ...
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2answers
54 views

Furnace keeps kicking off and on

My furnace runs for a few min then flickers and shuts off and then the system recycles and it fires back up and the process repeats over and over and over etc....
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6answers
6k views

How do I prevent ice stalagmites from building up on the furnace exhaust?

I have a high efficiency furnace that exhausts via a pvc pipe out the side of the house, the trouble is the moisture from the exhaust forms an ice stalagmite in my driveway in the cold weather. Are ...
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2answers
24 views

How much difference does hot vs cold air make with regards to an Aprilaire 600 furnace humidifier evaporation rate?

If I run the humidifier only when the heat is on, I get good evaporation. However, I want to consider also running it with just the fan running because our furnace doesn't run all that often. Will I ...
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104 views

Very old, Coleman, through the wall (double sided) mounted gas heater not working

My home was built in 1957, I had a new heat pump system put in (which I now hate) 7 years ago. It works fine in the summer, but in winter it doesn't heat the house very well. At the time, I kept the ...
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2answers
1k views

How is a high altitude natural gas burner different?

What is the difference between high altitude natural gas burner and conventional low altitude gas burner and why high altitude natural gas burner are needed?
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1answer
75 views

How do I wire my furnace humidifier so it comes on any time the fan is on?

I have an Aprilaire 600a humidifier from a few years ago and currently it's wired into my furnace with two control wires labeled "W/G" and "Cf". The "W/G" is connected to the W terminal on the ...
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5answers
580 views

Low voltage fuse blowing in furnace

I have an outside A/C compressor and indoor furnace fan combo in the attic. The unit was off and the 3 amp fuse was blown. I replaced the fuse and used the thermostat to turn the fan on followed by ...
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2answers
30 views

Furnace fan runs all the time

our furnace fan runs all the time It doesn't switch off when the furnace does and keeps blowing cool air I've replaced the filter and it's still running The thermostat (RTH6400D) isn't set up to ...
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3answers
9k views

What could cause a flame sensor to stop working so frequently?

Over a year ago after a month in our new house, we came back one evening to a cold home and after some googling, I found out that the flame sensor was dirty and the furnace was starting the flame and ...
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1answer
39 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 ...
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3answers
8k views

Does a whole house humidifier go on the intake or outlet of the furnace?

On what side of the furnace do I install the tank of the humidifier (the warm side or the return air side)?
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2k 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 ...
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1answer
34 views

Can I replace the permanent filter in my furnace?

In my furnace (ruud ubhc-17j14sfa), there is a permanent, washable filter. It was there when we moved in 2 years ago. The house is about 10 years old now. The filter is pretty simple, more like a ...
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1answer
48 views

Pilot lights, but main burners don't on furnace with no flame sensor

I have a Rheem furnace in my house. It recently stopped working. It is the type where the pilot is not always on. Anyways, the ignition will kick in, and the pilot lights just fine. However, the ...
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5answers
18k 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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0answers
163 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 ...
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2answers
51 views

Are my heat pumps using the right amount of power?

I'm trying to figure out if our two heat pumps are being power hogs and if there is something to do about it, or if they're operating normally. We bought our home recently and haven't been in it but a ...
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1answer
62 views

HVAC Contractor Didn't Install Drip Pan

I recently got the A/C unit and furnace in my basement replaced. When the company came out to do the quote, they stated that they thought I should have a drip pan, and the proposal that they gave me ...
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2answers
34k 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 ...
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2answers
16k 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 ...
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0answers
51 views

Can a furnace safety limit switch with manual reset be changed out with an auto reset switch?

I have a Ruud natural gas furnace from 1987. Overall it works well. I've had my home warranty service send out an HVAC tech a couple times for the high limit switch needing to be reset. It's a manual ...
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0answers
55 views

Is the Thermostat controlling the wrong zone? (Multi-zone heating with gas furnace)

UPDATE 12-29-2015: I've poked around and found, what I believe is, the board controlling the zones (Trol-A-Temp Mini-zone). Before I make any changes there, I chose to replace the thermostat on the ...
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1answer
69 views

How to wire a C-wire from a humidifier to a Carrier furnace?

I need guidance on a wire. One wire connects the humidistat to HUM. Another wire should go from the humidifier to COM24Vac. My COM is taken as you see in the picture. Is it an issue to wire the second ...
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2answers
1k views

Hvac Fan only blows in 'fan on' mode while heating

Our HVAC Fan only blows in 'fan on' mode while heating. In other words the fan will not blow in heat mode if switched to "fan auto". Both fan on and fan auto modes work when cooling. See image below, ...
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3answers
289 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 ...
4
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1answer
565 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 ...
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1answer
83 views

Thermopride OL5-85 oil furnace no longer works

We bought this old house where the oil furnace worked for a while. Now it does not work even after adding enough oil and priming the furnace. We have already pushed the reset button..so I do not dare ...
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1answer
509 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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2answers
27k views

How can I determine why my furnace is not blowing enough heat?

During a cold spell last week when temperatures got down to -23f (-31C) my furnace started showing issues with blowing enough air and the air was not very warm. Last winter it did not have any issues ...
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2answers
44 views

Can I retrofit a 2-speed or variable speed blower on a Payne PG8UAA forced air furnace?

My furnace blower is rather loud and runs at one speed. I wish to have the blower run at a slower speed to mix the air in the house when the heat is not called for. I see some furnaces have ...
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0answers
37 views

Oil furnace fan timing, limit temp setting

I just installed a new Crown oil furnace and a two wire thermostat. The furnace fires up fine but the blower won't turn on until it shuts down and the high temp limit control takes over. Then the ...