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 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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19 views

Furnace fan starts slow and is getting slower

here is a sound clip, start at about :55 or listen to whole thing! https://clyp.it/3h54oe2q model is tg9s060b12mp11 luxaire, which comes up as York most places. Anyhow, what's the best way to ...
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3answers
48 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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10 views

RUUD Furnace blowing air but not heat

I have a RUUD furnace that stopped blowing hot air last night. I was thinking that it was the high limit switch gone bad BUT the coil ignites and lights but then goes out again after a minute, so ...
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29 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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2answers
58 views

Where do I connect a C wire in a Rheem Furnace REAB 1415J?

I'm upgrading the thermostat with a Honeywell wifi one. I found all cables at the thermostat end, but can't figure out where to connect the C wire to the furnace (Rheem REAB 1415J).
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19 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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1answer
18 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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2answers
34 views

No water pressure in heating circuit

I have a natural gas hot water furnace and I can't get heat. First I turn up the temperature at the thermostat and I hear the furnace turn on, the supply line gets hot and half way down the line it ...
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2answers
41 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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43 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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21 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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95 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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1answer
21 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
32 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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2answers
36 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
43 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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34 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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37 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
45 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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1answer
244 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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2answers
33 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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31 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 ...
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35 views

wiring in a electric furnace to electrical subpanel

I have a 30 amp double breaker in my main home panel feeding my detached garage 100amp sub panel. Can i run a electric furnace with a 90 amp breaker in the subpanel. Or is this setup all wrong
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60 views

Furnace fan works properly intermittently

My furnace fan sometimes stays on and runs continuously. I can stop it by flipping the breaker for the furnace on and off. It then stays off. When heat is called for, the fan comes on again and ...
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75 views

My furnace has a C - common wire but air conditioner uses it - how to hook up smart thermostat?

I bought an ecobee3 smart thermostat which requires the C wire. At my furnace there is no circuit board but there was a diagram and I was able to locate the C - common wire, but it seems to be used ...
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1answer
88 views

hooking up a humidifier on a carrier infinity furnace

Hello I would like to hook up my desert spring rotary disc humidifier to my new carrier infinity model #59MN7 furnace. I see the control board in the furnace has a HUM (humidifier) terminal and a ...
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48 views

new furnace hurts eardrums

I just got a new furnace in my 800 sq. ft apartment. Single stage 80% efficiency 40K BTU Coleman. It seems much louder than my old one. The burners and the blower. And when I walk past the (single) ...
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1answer
82 views

Furnace: are flames in between the tubes bad?

In a Carrier Weathermaker 8000 gas furnace, is it normal for some of the flames to be coming out of the spacers in between the tubes? It seems like they shouldn't be there, since they aren't going ...
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1answer
49 views

Actual efficiency of an old oil furnace?

We purchased a house with what appeared to be a relatively well-maintained oil furnace, about 30 years old (installed in 1984). We don't have any records of annual oil usage, or any way to find that ...
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37 views

question about a gas furnace having to light repeatedly

I am new to this forum, but I will do my best to answer any questions I can (I am a general contractor with a background in engineering and residential construction and machine design) so, here is my ...
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41 views

Furnace on the Fritz - Any help greatly appreciated

I have a Tran XL90 - Model #: TUX100R948W6 It does not turn on in the "Auto" position on the thermostat. The fan does come on in the "On" position. However, it doesn't blow hot air. It has 3 ...
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miller mobile home furnace

When I press the reset button my furnace turns on and goes what seems to be a complete cycle. At this time the heat comes from the register nice and strong. When it comes on the second time it shuts ...
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5answers
206 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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1answer
33 views

0v at DC thermostat terminal in furnace

I have an old (mid 80s) Rheem gas furnace I hope will last me through at least one more California winter. It's been known to go down into the upper fifties, so it has its work cut out for it. In any ...
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1answer
53 views

Furnace Fuse Blows Immediately

This afternoon, our Ruud furnace suddenly stopped working. After poking around a bit, I realized that the 3A fuse on the control board had blown. I ran to the hardware store and replaced it, but no ...
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Can I use any C terminal on a furnace to supply power to a thermostat? [duplicate]

I have a dual heat system with a gas and electric plenum. trying to install a wifi thermostat and found that the C wire on the furnace is connected but once it goes up and through the electric plenum ...
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187 views

No C wire terminal on my electric plenum but there is on my furnace. How do I solve?

I had a brand new furnace installed recently but also now picked up a wifi thermostat. The problem I now encountered while installing the thermostat is that my system also has an electric plenum as ...
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44 views

wiring for rheem 2 stage furnace

I am trying to wire a Honeywell 2 stage thermostat to a Rheem classic 90 gas furnace. At the furnace there is a white wire with a red strand connected to the R post, a blue to the C, green to G, ...
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2answers
72 views

Rain water leaking around attic furnace

I bought a house a few months ago and when I bought it I noticed what appeared to be a water spot on the ceiling of the top floor. Of course I didn't do anything about it until heavy rains over the ...
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1answer
89 views

How does old wood furnace work?

My mother in law has an old wood furnace in her workshop. It obviously is different than the typical wood stove you see. Does anyone have one of these? Or can anyone explain the theory behind its ...
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1answer
107 views

Correct Wiring for Furnace Blower Motor

After getting my furnace blower motor replaced, it now runs only in the following scenarios: 1. Mode "Cool" Fan "Auto" 2. Mode "Cool" Fan "On" 3. Mode "Heat" Fan "On" In other words it will not run ...
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48 views

Need help with a Trane XR90 gas furnace not heating

Diagnostic blinking light is 3. Tried calling Trane with no returned call and its getting really cold tonight. 30 degrees. Help plese
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2answers
516 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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59 views

Replace or wash this furnace filter?

My mom's furnace has ductwork until right next to the furnace, where the return air instead goes into an obsolete electronic air cleaner that is basically as big as the furnace itself. The issue is ...
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1answer
71 views

Cant I just use a 24v wall instead of a tranformer?

I can just use a 24v wall transformer that I have plugged into my sprinkler system and use that in place of the transformer on my electric Central coleman furnace right? I would connect the hot line ...
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1answer
171 views

What is the optimal duty cycle for a furnace?

A heat load calculation of my home says it requires ~36K BTU/hr of heat at a normal winter temperature (40°F), and ~52K BTU/hr at the design temperature (24°F). An HVAC contractor has proposed ...
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1answer
45 views

How do I switch the furnace to heat mode?

I have an older good Sears furnace. It was on cool mode this summer and the fan could come on. I can't find how to switch it back to heat mode! Thanks. Linda
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1answer
527 views

What does this device on my new furnace do?

Can someone please tell me what this is? I had a 35-year old oil furnace replaced recently and the new furnace is obviously more complex and has many safety features the old one didn't. I've looked it ...
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1answer
56 views

How do I compare furnace models?

I need a new furnace, and I have quotes from two companies, for three different brands of furnace, Carrier, Trane, and Lennox. Both companies have provided the model numbers of the units they would ...