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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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Is it safe to replace a Furnace pressure switch with one of a different rating? [duplicate]

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 ...
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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 ...
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1answer
51 views

TV, Monitor reset periodically

Recently moved into this house, built in 1994: Computer monitor resets: This happens periodically (possibly when large electrical appliances kick on like the fridge), but it also happens almost every ...
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2k views

Can I install a modern furnace without ductwork?

I removed an old coal furnace from my basement. The furnace did not have any duct work to speak of. There was an exhaust pipe which fed into the chimney and a duct that went into the next room, but ...
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1answer
33 views

Why does my oil furnace cycle quickly?

I have a Rheem ROBF-067LBEA949 oil furnace as part of a forced-air Rheem UPNL-036JAZ heat-pump heating-and-cooling system, controlled by a Honeywell TH5220D1029 thermostat in its 2H1C w/ AUX ...
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1answer
68 views

What is causing intermittent furnace ignition failure? How to Diagnosis?

I have been researching how to diagnose this intermittent lighting issue with my furnace but the common issues do not seem to apply. Blower turns on Ignition coil turns cherry red Sound of gas blower ...
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2answers
1k views

Thermostat set at 65 - Furnace went to 90 - possible causes?

Oil furnace. Honeywell programmable thermostat (not WiFi-battery operated). Heat set as always at 65 degrees F with auto fan. No changes to settings whatsoever. Had been working fine all winter. ...
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1answer
2k views

Why is there a vent on the ductwork coming right from the furnace?

Why is there a vent on the ductwork coming right from the furnace? I have a typical furnace for a 1400sqft house in Michigan. I also have central air which runs through the same duct work. There is a ...
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1answer
387 views

Furnace failing intermittently, is it a faulty furnace pressure switch?

Furnace info Type: York Stellar Plus (HE down-flow condensing) Model number: P2UDD12N09501C Problem My furnace is intermittently failing, i.e. it stops producing heat. When it fails, the induction ...
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3answers
200 views

Wiring for humidifier to Goodman gmpn080-4 furnace

I have a Goodman gmpn080-4 furnace and am installing a Skuttle 190-1 humidifier. Where do I wire the two wires from the humidistat to the furnace? I see a 24v HUM screw on the board, but not sure ...
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2answers
139 views

Coleman furnace flame quits after 20 minutes

Coleman DGAA090BDTA furnace flame quits after 20 minutes, below thermostat temperature. Fails after 3 auto attempts to reignite. I power cycle unit, still does not ignite. Wait 15 minutes, ...
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4answers
208 views

Is this stuff in my furnace toxic?

I am in the process of removing an old coal furnace. after removing the natural gas conversion kit I now see some type of loose filler or insulation which was present around the conversion kit pipe. ...
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1k views

Gas fireplace is connected to the thermostat. Is there a way to disconnect?

New home has a gas fireplace that that we believe is connected to our thermostat. The fire will turn on/off continuously. Is there a way to disconnect it so we can just have the fireplace ON ...
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1answer
356 views

Gas furnace control board issues: main burners never start; sparks never stop w/o flame sensor

I have a gas furnace that uses an intermittent pilot/ignition to light the pilot. The furnace itself is having problems starting the main burners, so I took a look. I found the following: When I turn ...
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1answer
7k views

Pilot won't stay lit after replacing thermocouple

The pilot won't stay lit on my furnace, when I release the button it just goes out. This started occurring after I did some gas plumbing and had to relight the pilot. I suspected the thermocouple ...
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1answer
70 views

Can a hot tub be installed in a utility room?

We just bought a house with a large, unfinished utility room in the basement, about 15 ft x 20 ft. The previous owner just used it for storage. It has washer/dryer hookups and contains the furnace and ...
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1answer
55 views

1999 Goodman furnace modeld GSMS060-3

Furnace goes through the normal start up process but after 5 minutes the flames go out and I hear a click in the induction motor not the main fan. What could I check. I have taken out the flame ...
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2answers
190 views

Do cold air return vents also supply combustion air?

I’m wondering if the cold air return vents located inside certain rooms of the house are also the intakes for furnace combustion air. In other words, are those the vents that feed fresh air into the ...
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1k views

What should the plenum temperature be on a modern furnace

I had a tech out to review my furnace that's not keeping up - a Trane XV80. They poked around, and saw that the plenum temperature is 95F. They then told me that it should be around 140F, which is ...
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1answer
454 views

Flame sensor in Trane XV90

I have Trane XV90 that was blowing cold air while it was on heat. I have recently changed the ignitor (which seems to work just fine) and the flame sensor (which seems to be failing already). I just ...
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3answers
8k 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 ...
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1answer
459 views

Not able to find Lennox ML193UH furnace filter

I have a Lennox Merit series gas furnace ML193UH in my attic. The furnace turns on, but no air blows out of it. So i figured the filter needs to be changed. But I'm not able to find it. The pictures ...
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36 views

What can cause a furnace to work worse

I have a 10 y/o trane xv80. It’s -3F in Chicago, and the furnace is struggling to keep 64F in the house, while set for 72. I don’t remember it being this bad in years past. I had the furnace taken ...
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1answer
59 views

Fuel oil burner running intermittently

Fuel oil (Beckett oil burner) here. It's -20°F outside right now and the house is at 61°F even though I have the thermostat cranked up to 75°F (we have a thermometer in the house as well, ...
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802 views

Need Help on Adding a Common Wire for Nest

I recently purchased a Nest thermostat. After couple weeks of usage, the Nest is constantly shut down due to low battery. I search online that adding a common wire is the go solution for this. However,...
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403 views

Hot surface ignitor does not glow occasionally

Can one of you experts please help with this unusual issue? The hot surface ignitor does not go on occasionally. So far, I had this issue 3 time in the past week. My furnace: York gas furnace with ...
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555 views

Goodman furnace starts after turning on / off 7 times

I have a Goodman furnace from 2000 has been running great until recently it does not seem to cinc with thermostat. when you shut unit down and turn back on it will go through all motions of starting ...
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2answers
271 views

Why would furnace not come on immediately?

I had a brief scare just now. It is 7-degrees right now and getting colder so I definitely don't want a furnace failure. I came home and house was at 62 with thermostat at 64 (my standard not-at-home ...
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1answer
192 views

Ecobee3 Setup and furnace only has W G R

My existing thermostat has 4 wires (missing C) so I'm attempting to use the Power Extender Kit (PEK) at the furnace control board. Only problem is, I only have 3 wires that are obviously labelled at ...
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1answer
66 views

Does anything look wrong with this Furnace burner start up?

Here is the back story: Starting to finish basement, needed to exhaust my furnace outside instead of drawing in air for combustion inside the house. Hired HVAC person to do this in the fall. Winter ...
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3answers
687 views

Why is the furnace heating the house far past the thermostat setting

Problem: Furnace came on as usual in the morning but failed to shut off after the set temp on the thermostat was reached. The house temp (as measured on the thermostat) reached about 10 degrees higher ...
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2answers
762 views

Furnace entering lockout mode - air flow problem?

I have a Nordyne KG7SA, about 2009 vintage, which has begun acting strangely. We started noticing that the thermostat would drop several degrees below the set temperature before engaging. More ...
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2answers
2k views

Can I add four new ducts to my HVAC trunk line?

I am finishing my basement and need some insight from someone who understand HVAC design. I would like to know if my main trunk line (the 34' one in the diagram) can handle another four 6" ducts off ...
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2answers
1k views

Can I use the Y wire in place of the C wire for my new thermostat?

I'm looking to wire a Honeywell Lyric T5 to my furnace (I do not have an air conditioner, I do have a humidistat). My current wiring at the thermostat is G,W,Y,R. At the furnace it's G,R,C, and 2 at W,...
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1answer
63 views

Rapid on/off cycling of furnace

My 50-year old wall furnace keeps cycling on and off as it gets near the set temperature. Can I fix this by changing to a new thermostat? It's a 2-conductor cable (no blower).
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1answer
310 views

Resonance in pipes, heating system

I have resonance in the heating system pipes. Touching the pipes near the boiler (natural gas) pump I can feel ever so slight vibration, most detectable by touching the pump motor. Background: About ...
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1answer
363 views

Armstrong S-25 Pump Motor Lubrication?

Recently replaced a leaking bearing assembly on my Armstrong S-25 pump. The previous one required oiling, the new one is the permanently lubricated MF/BF model. I look forward to not having to ...
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1answer
2k views

Thermostat won't always start heater on its own

I have a gas furnace that seems to work fine; it keeps the house warm when things are running as expected. Sometimes, however, we'll notice the house is getting cold. The temperature on the ...
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1answer
5k views

HELP!! Why is my stove turning my lights and furnace back on when they go out?

For the last few days whenever I have more than one or three lights on they go out(includes the furnace) and the only thing that turns them back on is my stove. What is this?!?!
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Furnace motor not kicking on

I have a goodman furnace who's fan motor will keep running. it's like it is trying to kick on, but it can't will run fast then slow down then fast again. the only way it will kick on is to turn ...
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3answers
1k views

Need info on AFCI requirements

Are AFCI breakers required on 30 amp dryer circuits and 50 amp furnace and stove circuits or just the 20 and 15's? I haven't done residential in a long time. Thanks fellas.
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0answers
44 views

furnace wont kick in

My furnace seems to work intermittently. overnight its seems to stop... i have checked the thermostat and it shows says it is heating. fan is on auto, but nothing coming out. when i turn heat to off, ...
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1answer
1k views

Blower motor turns on before furnace heats up all the way

I have a Honeywell furnace and when it starts the exhaust fan kicks on then the flame starts (it's a propane furnace) it warms up between 30 seconds to a minute then the main blower kicks on but it ...
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0answers
2k views

Goodman gas furnace won't light

I am trying to resurrect a Goodman gas furnace that hasn't run in a few years. I have gas to the unit, but no ignition. Vent blower starts up initially, but soon goes to intermittent operation, I ...
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1answer
203 views

Where to connect c wire

I’m installing a new WiFi thermostat that needs the c wire. I ended up running new thermostat wires that contained the common wire but now I’m stuck on where to connect it to the furnace. Can ...
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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 ...
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1answer
476 views

C Wire for Thermostat

I am upgrading my thermostat (Have AC & Heat) and found that it doesn't have the "C" wire that I need to power my new thermostat. The furnace does have a terminal for C, but only condensation pump ...
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1answer
826 views

Aprilaire 56 Humidistat not getting power

I have an Aprialaire 56 humidistat that is connected to an Aprialaire 560 humidifier. Currently the humidifier is not turning on and after testing the wiring with a multimeter, the wires going in to ...
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1answer
1k views

Separate furnace & a/c units on same breaker

Long story short: with both units on one breaker, each one is kicking on one after the other to try to reach one temperature. I have turned the a/c disconnect at the outside box, and the a/c is still ...
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1answer
3k views

Blower fan works w/ a/c “auto”, not with heat “auto”

I know there are similar questions out there but are there any new ideas? When I turn on my heater, the gas fires up but the fan doesn't turn on. I know the fan is still working because it will turn ...