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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Furnace/HVAC issues in new build

Just had a couple of questions. I have been in new build townhouse for a month and noticed a couple of things but have been away several weeks so just dealing with it now. Some of this I am sure I am ...
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Furnace relay - old one says 18 LRA, replacement says 48 LRA - Does it matter?

forgive me if this is a newbie question. I am replacing a relay inside an electrical furnace/air handler. It is a relay model 90-293Q. The original one I have specifies it as "8 FLA, 18 LRA" but the ...
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Only getting 15-16 volts from Furnace R and C

I recently purchased a smart thermostat. Because it needed a common wire and I only had a 3 wire setup, I ran a new thermostat wire to my furnace. However, I now get only 15 volts (inconsistently, ...
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Water around furnace: culprit?

Problem: After heavy rain, water pools around our basement furnace. After climbing onto the roof, I found a mysterious (plumbing?) vent. This post seemed relevant, but 0.5 gallons comes in after a ...
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Add common wire to furnace

Trying to add common wire to furnace for smart thermostat. Looking at wiring diagram, it looks like common wire off transformer is blue, switches wire color to white (via wire cap), then back to blue (...
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My blower fan won't turn on unless AC is running

So first of all, I've changed nothing: same thermostat and same everything. I typically run my blower fan 24/7, but a few days ago it stopped working unless the AC is on. Which tells me that the ...
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Wiring AC condenser to Furnace

Hello So this is what I was left with I am trying to tie in fan on/off and a AC condenser I have 2 wires for my limit switch, 2 wires from my 24ac transformer, 2 wires from my AC condenser and 2 from ...
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Ecobee installation with two Rh wires, occupied G wire and HRV

I just moved to North America from Europe (hence why furnaces, HRV systems etc are totally alien to me) and I'm having trouble understanding how to wire up an ecobee3 lite to replace my Honeywell ...
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Could my furnace be leaking due to condensation neutralizer?

I posted this and the main suspect was condensation pump but after troubleshooting, the pump is working fine (tested standalone). Now I wonder if the leak could be due to the condensation neutralizer; ...
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Chronic Flame Sensor Failure - Furnace and Water Heater

My house is 9 years old. About 5 years ago the Lennox gas furnace began to go into lockout. The problem was diagnosed as a dirty flame sensor. Shortly after, the same problem occurred with the Rheem ...
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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 ...
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Possible to have more than one wire connected to “G” terminal in furnace?

I have a 25 year old gas furnace without A/C. I had a 2 wire basic thermostat that I have replaced the wiring with 5 wires and also a new Nest 3rd generation thermostat. On the wall beside the ...
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Thermostat wire does not go to Furnace

My thermostat wires go to a control panel heat pump system which go to the furnance , i need to wire a c wire but not sure how to go about this with the york control panel
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Furnace blower cutting in and out during A/C use

Backstory: I fired up my air condition for the first time this season (single family house) and felt lukewarm air coming out of my ducts. When i went outside i saw that the condenser was not turning ...
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Fuel gas CSST line allowed in plenum in Texas?

I recently visited a house. The host pointed out something interesting. The furnace AC combo is in an indoor closet and is vertical upflow and sits on top of a filter base that sits on top of the ...
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Goodman furnace - C Wire connection

I'm trying to connect the C wire in my Goodman furnace in order to install a new thermostat. I've read all the posts on this forum about this specific issue so my question is whether i'm in the right ...
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Furnace's contacts getting dirty

The two copper wires inside our furnace, that are supposed to ignite the gas, get too dirty to do the job about twice a year... We then have to go there -- always at inopportune times -- remove two ...
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Can the wire from the y terminal on thermostat be connected to the c terminal on heater board as pictures show?

My nest was installed with no c wire and it lost power. At this point the tech looked at the wiring diagram in a/c unit outside but I do not know what he did. A/c worked but later nest had no power. I ...
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Frozen drain line into septic from furnace

Last winter the condensation from our high efficiency furnace caused our line to freeze from the floor drain where the water was running into, all the way to the septic. No one was there to flush ...
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Lennox Furnace Blower not working on AC In On or Auto

Please Help! I have a Lennox Furnace Model G60uhv(X) after years of working fine I switched the thermostat to AC and it failed to start the cooling cycle. I suspect some sort of problem with the ...
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53 views

Line to AC dripping at the furnace

My line from my exterior AC unit is dripping at the furnace. The dripping over time has caused rusting and we've had to replace the control board under it. It appears the root cause of the problem ...
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Furnace Connect G Wire

I have a dual energy electric/oil furnace that is wired to a thermostat with 2 wires R and W. I don't have any AC. Inside the furnace there is a switch relay to control the fan but it is not connected ...
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I have an unused C wire hooked up to thermostat and have no idea where to connect it to the furnace for power

I know this question gets asked all the time but I've spent hours staring at forums as well as my furnace and at this point I'm desperate. I just bought a nest thermostat that needs a C wire ...
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HVAC blower fan won't stop

FINAL UPDATE: I have found the culprit - the Nest thermostat itself. First, I disconnected the t'stat at the control panel and found out that the fan would no longer start upon powering the system. ...
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Need to identify wires coming from external AC Unit

idiot DIY'er here :P. I recently installed a smart thermostat and long story short; I removed the two wires from my furnace's board for the external air conditioning unit in the process. I was going ...
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Exhaust Fan Runs With No Power at All!

How can my furnace exhaust fan run with the power off, the thermostat off, and the breaker off?!
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Furnace with no “C” connection

I have a mobile home furnace. This furnace only has a 4 wire connection terminal, G,W,R,Y. I also have a condensing unit outside with the 24 volt 2 wires coming to the furnace. I know I connect one to ...
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Furnace Pilot Flame ON constant but Main Burner never kicks in

I own an older furnace (Armstrong EG6F80DC12-6 -- natural gas, forced air, single stage, Honeywell S8600C Continuous Re-Try Module, VR8204A Gas Valve w/ Pilot Burner / Igniter-Sensor). It has been ...
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Lennox Furnace Troubleshoot Assist

I have a Lennox Elite G50UH-24A-070-15. It quit entirely and threw the error "Pressure Switch open or blocked" according to the diagnostics panel on the front. Recent renos so thought it was clogged/...
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Why is there a minimum distance to a corner from a direct vent exhaust?

According to the instructions for my direct vent furnace, (item #4) the minimum distance from the center of the vent to the nearest corner is 16 inches. Why is that important? I understand the ...
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Furnace Pressure Switch Testing

I have a ComfortMaker combination furnace/AC for the back part of my house. The furnace kicks in, but never heats up. No errors are reported. Started troubleshooting and took a peek at the pressure ...
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positive pressure in a furnace room

I am planning to install an insulated exterior grade door on a finished furnace room in my basement. The room will have a hot air supply register but i read that I cannot put in a return because i ...
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What is the right way to extend a furnace intake pipe under a brick patio?

Our gas furnace intake (one of them, there are other intakes inside the house) currently comes out the side of the house but under a brick patio. It seems that the previous owner of the house extended ...
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Furnace heat satisfied but inducer starts and ingnition tries over and over

I have a Heil furnace 90 plus mfg 1989, Heat cycle is satisfied and thermostat is not calling for heat. Induced draft motor starts, spark igniter starts, blower starts and runs like this for 3-4 ...
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Trane XV80 furnace, two wire setup, wanting continuous fan when no heat is needed

I found the "Why doesn't the “fan on” mode work after I installed a new thermostat?" thread on this site and am wondering if the manual rewire steps would also work for a two wire system. The setup: ...
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No C terminal on furnace to connect a wifi thermostat

I have an new Emerson thermostat and would like to connect a c wire so it always has power. I have an extra wire that's not being used, but I don't have a C wire terminal on my furnace. I'm wondering ...
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Pilot light keeps going out

I have a Coleman mobile home furnace and my pilot light keeps going out. I have replaced the thermocouple twice, cleaned the orfice, replace the gas regulator with a brand new one, and even crawled ...
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I have a bryant air handler where the power to thermostat is lost

I have replaced thermostat with a new one, changed the circuit board out twice due to wasn't getting power to thermostat. when I power up after wiring in connections. fan comes on for a moment along ...
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Adding split AC to a Dayton oil fired forced hot air furnace

I'm trying to add split central air to my Dayton oil fired forced hot air furnace, mod # 3E268A. The manual clearly says it can accept this but the terminal block in the unit only has (4) lugs. TT and ...
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How to troubleshoot gas supply not making it to some appliances

I recently purchased a home and once utilities were turned on I've been having issues with certain gas appliances. Some appliances required a normal amount of time to get the gas flowing after being ...
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Using existing exhaust stack for new furnace

I'm about to replace the furnace in our house. The existing furnace uses a 6" stack through the roof. I know most new furnace installations just use PVC and poke out of the wall at about ground level. ...
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Unable to locate filter on Gas Furnace

Can not find where the filter for this furnace is. It is a gas Rheem Criterion II. Have watched YouTube videos but none look like mine. Thermostat keeps saying filter needs replacement.
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What's the right size pipe to buy for gas supply for this furnace?

I'm trying to figure out the right pipe to buy for a direct vent wall furnace. The instructions show 3/8 inch npt, and also say that the gas inlet is 1/2 inch. When I measure the gas inlet it appears ...
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Does anyone know what this type of furnace/heater is called?

I have this old style of heating but I cannot find any information on it. Can anyone help? It's gas and just sorta gets hot heating the house. No blower, no ducts, just the exhaust. The brand on the ...
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Furnace blower comes on full time when the thermostat is set to Auto

I have a Maytag furnace and the blower motor comes on right away when the thermostat is placed in auto and stays on when reaching the temperature set point and the heat goes off. I have replaced the ...
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Rheem 45,000 BTU gas furnace wiring- 1991 year

What are Rheem 45,000 BTU gas furnace wiring connections for the older hot surface control board? 1991 year model: rgde-04nhacr
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Trane Furnace Fan Works, But Heater Won't Run

As stated, my heat isn't coming on. When this started: Everything has been all fine and dandy all winter. The other day I ran the fan only for a few hours without the heat. After this, my heat ...
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Furnace control board wiring - swapped on adaptor?

I am trying to replace my Goodman control panel (see this question), and have a wiring question. The new control panel (50M56U-843) that I acquired came with a large variety of wire adaptors. I ...
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Dropped item in furnace duct

While trying to stop the ticking noise coning from my furnace ducts, I accidentally dropped a small piece of fire retardant foam (as you can see in the below photos) in one of the vertical furnace ...