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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21 views

Goodman furnace - intermittantly works (80% of time works, then one blink (ignition failure)

Goodman furnace - works most of the time. Then, it will give the one-blink indicator of ignition failure. We either wait for it to cycle (which can take 30m-1hr) or turn off the power to the furnace ...
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2answers
49 views

Can 2 stage furnace be forced to stay in low?

Can 2 stage furnace be forced to stay in low? My airflow noise (and duct pops) is loud enough to wake me up, so I want to test if low reduces this problem enough before I rip into the finished spaces ...
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1answer
55 views

Sticky black liquid coming from Furnace / AC Unit

I have this sticky black liquid slowly leaking from my gas furnace / ac unit. I called an HVAC repairman and he wasn’t sure what it was. He said he thinks it’s an old drip pan made of tar (not sure ...
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30 views

No C terminal on furnace. Workarounds? Possible the AC?

I'm Trying to connect my C wire to install a new thermostat but the furnace doesn't have a C terminal. In my readings on this I found that because I have an AC,I can connect my C to one of the wires ...
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1answer
23 views

Furnace Fan (Heat Pump) having issues when starting sometimes with a buzzing noise

We have a Central Electric Furnace model # EB12B. It is paired with a heat pump. We noticed the issue when we were running the A/C this year and is has continued while running the heater. When the ...
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14 views

Heating, and furnace making noise

Why does my Goodman gas furnace sound like a jet plane when the burner kicks on.My fan kicks on first,then the heat comes on,but sounds like a jet firing up.
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19 views

Gas furnace ignites but then makes large knocking sound

My gas furnace will ignite, but after the pilot goes on for a moment it creates a large periodic knocking sound over and over again instead of the fan starting. I have my suspicions, but I wanted to ...
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3answers
92 views

(SOLVED) What is a whining, high pitch sound coming from my furnace when heat kicks in

EDIT: SOLVED. IT WAS THE FLEX CONNECTOR. THANKS EVERYONE. My gas furnace makes a high-pitched whining sound when the burners turn on (when I can see fire). A repair man came and told me it may be that ...
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4answers
147 views

Considerations for installing a high efficiency furnace in my attic?

I live in Upstate NY and in the winter it gets below 0° F. I currently have baseboard water heating throughout my home. Prior to this I believe there was a gravity furnace which supplied the house ...
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1answer
26 views

Tempstar 2 stage furnace restarting every 7 minutes - not going into high

I have a tempstar 9MPT model based furnace. Also sold under a number of other brands - comfort air, etc. It is a two stage heating with a PSC motor high efficiency furnace. After about 7 minutes of ...
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28 views

Thermostats with or without variable temperature differential (swing)

I am looking at replacing my thermostat, and don't really need or want one with geosync. I am thinking of the honeywell RTH9585wf. Currently I have a lux that is not wifi but programmable. It ...
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30 views

Water Dripping From HVAC Furnace PVC

I have 2 PVC pipes coming out of my TRANE gas furnace. Today I noticed that one is dripping water from the top. Picture attached. Its a slow drip. What could this be?
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2answers
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Tempstar (ICP) furnace short cycle (runs 10 -15 minutes) then repeats

I have a tempstar (ICP) furnace put in when the house builder built the house. Model is N9MPD075F12A2. Installed late 2009. This problem only happens with the furnace not the AC. When calling for ...
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1answer
20 views

How do I purge the air from a hot water furnace with zones

I want to try and bleed the air from my hydronic ( baseboard ) heating system. It's a natural gas system, I think I understand the basic functionality but my system seems to be a bit unusual and I'm ...
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2answers
36 views

Oil burner runs for at least one cycle then safety locks out

I have an older Slant Fin Liberty oil furnace that safeties out sometime around 4 hours. It seems to be intermittent because I have seen it do more than one cycle. The recent history on it is about a ...
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1answer
82 views

Neighbor's furnace exhaust

My neighbor's house sits 20ft from mine. Their furnace exhausts out the side of their house about 3 ft above the ground. The exhaust is blowing onto the side of my house and into the attic vent. ...
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26 views

Furnace not staying on

When my heater starts up it will light and run for approximately 5 minutes and then it trips a limit switch, will not relight until I reset switch. What's causing switch to trip?
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17 views

Furnace/thermostat require constant power reset/“reboot”

I have an AprilaireProgrammable thermostat attached to York furnace?Ac unit. The set point is usually around 22 degrees, and the room temperature is reading around 20 degrees. The furnace is not ...
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1answer
175 views

No C Wire Nest Thermostat

I just installed a nest thermostat. The previous thermostat did not have a C wire attached. It G, RC, (RH Jumper), Y and W. When I hooked up the nest thermostat it was short cycling the blower fan ...
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1answer
14 views

What is the proper replacement igniter for my York furnace?

I replaced one of these before on another unit but the part number was printed on the igniter. This one is not so, being ignorant to HVAC I just want to make sure I get the appropriate part. York ...
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2answers
46 views

How to figure out how to wire a 2 wire furnace to 3 wire thermostat

I have a 2 wire furnace and want to wire a 3 wire thermostat. My red wire is connected to the c in the transformer and the white is connected to the load. It works fine 2 wire but I dont want to mess ...
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2answers
59 views

Water is dripping from the furnace exaust flue

I replaced my hvac and noticed that my flue is dripping water. Wondering what might cause it? I assume some sort of condensation, but I don’t know what should I do to fix it.
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1answer
56 views

Wired “like” a dual transformer

I'm trying to update to a smart thermostat and my current one is wired like a dual transformer but I only have a single hvac system in the basement. Any idea why? My plan is to move the blackwire ...
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1answer
23 views

Furnace shutoff switch outlet only hot when furnace is running

I have an old Aprilaire 700 powered by the 110v outlet on the side of my furnace. I recently replaced the old humidistat with a newer Aprilaire 60 Digital. This humidistat comes with the blower ...
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1answer
45 views

Use a 2-wire line voltage thermostat on a 24v / low voltage 2-wire furnace

This is an ancient furnace at my aging mother's. Basic 24v thermostat, two wires only, the original from my childhood used a mercury switch. There are some commercial, line voltage, 2-wire thermostats ...
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1answer
42 views

Where to connect C wire on older furnace

Upgrading to a wifi thermostat and already have extra unused wire from furnace to wall, just not sure where to connect it at the furnace. I do have central air installed, and assume the blue wire ...
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2answers
45 views

Fan blower motor of Bryant furnace keeps running after flame is off

Fan blower motor keeps running in winder after the room temperature reaches the setting. Occasionally, especially in the case that the outside temperature is very low, the motor stops as expected. But ...
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1answer
56 views

Can I place a cap on my furnace exhaust to keep rainwater out?

I have a Lennox high efficiency furnace the vents out the roof with plastic piping, both fresh air and exhaust. The fresh air pipe terminates above the roof with a U-shaped pipe at the end of it, I ...
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1answer
25 views

Furnace Inducer Whirrs on and off before igniting, works when I tap circuit board

My furnace gets the signal from the thermostat, then about half of the time, the inducer motor whirrs on and off over and over. Sometimes it runs continuously without ever lighting. When I open it up,...
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1answer
39 views

Small part of filler in furnace is stuck. Can I still insert a new filter?

Bottom of furnace filter stuck can I still put new one in
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1answer
31 views

motor wire pinout

i have an older furnace and i need to change out the blower motor soon the original motor is getting bad. bushing bad. anyway i got another motor the same frame size but it came with 4 wires. white ...
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3answers
99 views

Furnace not turning on, and can anyone identify these sensors?

My home has a gas furnace with electronic ignition (intermittent pilot). Sometimes it doesn't want to start up, even with the thermostat turned up, and it indicating heat should be on. The fan-only ...
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2answers
52 views

How should I know if my humidifier work?

I have a Aprilaire 600 Humidifier installed in my basement, as per the manual it should automatically kick off when the lack of humidity is detected. It didn't seem happening. After I adjusted the ...
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1answer
37 views

Furnace Troubleshooting- Inconsistent Error Codes

My American Standard furnace ("Standard" Model, year 2003, 12 or 13 SEER) gave an Error Code 2 when first turned on- "External lockout, retries or recycles exceeded." (4 fail to ignite cycles ...
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1answer
135 views

Furnace Blower Motor fan hums but wont start

Furnace Blower Motor fan hums but wont start until I turn it by hand, then it runs fine. What should I check?
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36 views

Trane XL1200 furnace not heating

I have an older Trane XL1200 gas pack furnace/AC. I just tried to turn on the furnace and nothing happened. Looking at the control board the led code told me it was a pressure switch problem. The ...
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0answers
29 views

AC being turned on when calling for humidity

My newly installed Skuttle HSP2000 steam humidifier, controlled by a Generalaire GFX3 humidistat and wired to a Lennox G40UH-48B-090-14 is turning on the AC when being called for humidity. I've ...
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1answer
60 views

is the 24v transformer output ~27v normal?

i found my carrier 58pha090-016 furnace had no flame with the igniter on, and exhaust fan running, etc. it kept trying 3 times then stop. i reset the power switch of the whole system, the same cycle ...
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2answers
55 views

Ruud furnace keeps blowing 24 VAC 2 Amp fuse within 12 hours

Help! 20 year old Ruud 90 Plus condensing gas furnace with JCI G961DAJ-2401 controller keeps blowing its 24V AC 2 Amp fuse. I tightened the wires, nothing looks wrong. I measured the current for each ...
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61 views

intertherm nordyne furnace pilot light keep blowing off

I have a thermordyne standard gas valve furnace model number M1GB 090A AW. I had this problem for almost 4 years, the pilot light will get blown out after one or two runs, and I have to relight it. ...
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2answers
91 views

After blowing heat the fan won't stop, continue blowing cold air for prolonged period of time (30+ min)

Not always, but often the furnace continue blowing cold air after blowing heat. It may blow cold air for more than 30 minutes. Under this conditions I also see the error code (8 red flashed) "Ignition ...
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1answer
36 views

Furnace heat duct for basement

I'm trying to install a heat exhaust vent on the side of the drywall in the basement, see pic. The issue is that the the register is too small for the boot. This is normal if the exhaust is in the ...
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1answer
50 views

I need a signal when my furnace fan turns on

I want to install a motorized fresh air damper that opens when my furnace fan comes on. Is there a place where I can pull this signal off of the furnace board? Thanks!
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47 views

How to newly wire furnace condensate pump that contains a safety switch?

I would like to replace my current Little Giant furnace condensate pump that has no safety switch with the Little Giant VCMA-15ULS, 65 GPH Automatic Condensate Removal Pump w/ Safety Switch - SKU ...
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1answer
1k views

How to electrically ground a gas furnace connected with an armoured cable

My gas furnace will not turn on. I verified 120V where the armoured cable enters the furance, so I was going to continue testing for voltage before and after the transformer (with the door safety ...
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1answer
77 views

Position of dryer vent relative to gas meter and furnace intake

As part of renovations to our house (built in the early 70s) we are reconfiguring the laundry room and moving appliances to the opposite wall. The laundry appliances will now be to the left of the ...
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1answer
76 views

Adding a C wire and fixing White vs Red on my Furnace

TLDR: I think I need to flip R and W wires, and to splice the blue (C) wire to the brown wire coming of the transformer. Is this correct? Long version: Like many others on here, I'm trying to add a ...
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1answer
56 views

April Aire 600 powers off while furnace is firing

After having a new furnace and AC installed in the summer of 2018, replacing my 20-year old equipment, the existing AprilAire 600 whole-house humidifier behaves differently than before. During the ...
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1answer
46 views

Secondary C Terminal on Furnace Circuit Board?

I was trying to install an Ecobee thermostat, and there was no C wire installed. When I went to install the power extender kit, I saw the standard C wire terminal was broken out of the black plastic ...
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23 views

Lennox G51MP shutting down with Primary/secondary switch fault

I have Lennox G51MP-48c-090-06 ~14yrs old, starting up for first time this season. It is throwing error code: Primary or secondary limit switch open. Unit shows normal operation when powered up and ...

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