(Heating, Ventilating, and Air Conditioning) For questions about installing, repairing, and troubleshooting HVAC systems.

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1answer
37 views

Do all HVAC units have a drain line?

I have a rental unit and I can not find a condensation drain line on the home heating unit. The unit is old and my question is do all heating units have a condensation drain? Thank you
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3answers
6k views

How to diagnose a broken Aprilaire humidifier (Model 600)?

I have an Aprilaire Humidifier Model 600 (or maybe 600M) mounted on my furnace. The humidifier is not turning on (i.e. letting water flow over the filter) when the furnace is on. The below images ...
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3answers
228 views

What is the correct way to seal/flash coolant lines through T1-11 siding?

Our contractor installed an AC compressor and did a poor job of it. He ran the AC coolant lines through the middle of the wall and then just squirted some expanding foam into the hole, like so: ...
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0answers
77 views

Why would my heat pump AUX be kicking on with 1 degree change?

So this is weird, and I literally just noticed it today. I have a Honeywell 5-1-1 Day Programmable Thermostat – RTH6450D. That works fine, I have a heat pump system (Carrier 2-ton). Today for some ...
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1answer
66 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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3answers
6k views

Is it possible to use my window A/C unit without actually installing it in the wall?

So, here's the dilemma. I want to install a window unit in my garage. I know how to do this, but my wife isn't supportive of the idea because we are trying to sell the house currently. Anyways, ...
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3answers
85 views

Bedroom not getting enough heat

I have a dedicated HVAC unit for the rooms on the second floor of my house. A bedroom at the opposite side to where the HVAC unit sits doesn't get enough AC or heat. Right now, in winter, that room ...
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2answers
35k 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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4answers
25k views

What to do about different rooms in the house being a completely different temperature?

I moved into a 30 year old home last December. There is a problem with the HVAC. I have included a very crude drawing of the floor plan The problem is that I can't maintain a comfortable ...
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2answers
533 views

Temporary fix for bad contactor?

After doing some replacement for the ac, the contactor stopped working. It won't close when I turn the ac on. when I pushed it in, the compressor was able to start. I can't go out to find a new one ...
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0answers
59 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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1answer
88 views

It sounds like water dripping when heat runs [closed]

We have a humidifier and I have shut that off but still hear the sound when the heat runs...anybody know any other possible solutions It's is a carrier weather maker 8000vs energy efficient gas ...
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1answer
283 views

Add a c-wire to 25+ year old Rheem furnace

I've looked at just about every post on adding a C-wire to power a WiFi thermostat but remain uncertain on how to proceed. The current installation on a Rheem RGAC-080A is two wire as here: XFMR - ...
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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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1answer
76 views

Insulating ducts in unfinished basement?

Hi I am looking to insulate circular metal air ducts in my basement because the air reaching some of the farther rooms (from furnace) on the second floor of my home is comparatively much cooler. I ...
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1answer
44 views

Repairing a rip in my hvac vent

A small section of canvas fabric connects the duct coming out of my furnace to the rest of the house. I noticed that there's quite a large rip in this fabric. Would it be best to use standard foil ...
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0answers
49 views

Could my New Hot Water Tank be improving my Furnace

I've gone thru 2 blower motors in my furnace in 3 yrs. Techs don't know why. I purchased a New Water Tank recently and it seems strange but my furnace is working better. Usually I could hear noises ...
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3answers
314 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 ...
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0answers
32 views

time delay adjustment on Rheem elect furnace

Upon a call for heat the blower motor starts too soon resulting in cool to cold air coming out of the ceiling registers until heat strips start heating up.Wires coming from thermostat connect to ...
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2answers
838 views

No electricity going to thermostat

Our old thermostat is working but I want to change to a new one (nest thermostat). I have two exact HVAC unit at home. I change one it works but when I change the second one it doesn't work because ...
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0answers
25 views

Where can I find a user manual for the Honeywell 32207455 thermostat?

How can I obtain a manual for the subject thermostat? There seems to be no manual on the internet. We are trying to adjust the system and run into several questions.
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2answers
320 views

AC won't turn on after replacing thermostat batteries

we replaced the batteries on our thermostat after they began flashing for a few minutes. We'd been using the heater up to that point. After replacing the batteries, the heater does not turn on ...
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0answers
36 views

goodman furnance just keeps runing no heat why

recently i have had problem with my goodman furnance all it seems to do is blow air on very low speed and does not seem to stop furnance just keeps running i replaced limit switch work fine but after ...
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1answer
54 views

How to wire programmable thermostat that doesn't have an E termimal

I am trying to replace a manual with programmable thermostat that is missing emergency heat (E) terminal. There are bits and pieces of information I have gathered but am still not clear. Can I leave ...
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2answers
60 views

How to HVAC service 3 floors without ducts in roof?

This is a little simplified, but not too much. I have architects and plans for a a two story house plus a basement. The house is about 80 feet by 20 feet with all stories extending the whole ...
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1answer
204 views

New Thermostat Ecobee3 to Old Galaxy GG-75 boiler - Needs common wire

I would like to replace my old thermostat with a new Ecobee3 thermostat. HVAC system is a Slantfin Galaxy GG75 boiler - single zone. (No air conditioner.) Current set-up has only a red and white ...
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0answers
53 views

HVAC - hot air flowing on both zones when only 1 zone should be on

I have 2-zone forced air heating, with separate thermostats for each zone. Normally, if the thermostat in zone 1 triggers the system to go on, the heat will only blow through the vents in zone 1. ...
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2answers
13k views

Furnace blower motor won't turn off

I've replaced both limit switches on my Comfortmaker furnace plus the control board. Blower continues to run and the unit will still heat my home. Component changeouts did not make a difference in ...
4
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3answers
1k views

Connection for C wire on Mastertrol Mark V zone control panel

I have spent hours searching the web for information on this 20+ year old zone control panel, which supports 3 zones of Heat and A/C. The thermostat I'm replacing (on Zone 3) connects to T4/T5/T6 as ...
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2answers
197 views

How can I use a portable A/C unit to cool my clean room?

So, I have built a room inside my shop, a clean room for finish and airbrushing. I want to cool this room as I spend more time in it than the rest of my shop (garage) So, I get a portable unit. ...
4
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2answers
268 views

How to repair buckled duct work inside wall?

Update I think the duct is actually fine. The duct connects to a register that is shared by two rooms. When heating, one room is gets hot, while the other is cool (not too cold). I think the problem ...
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2answers
140 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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0answers
17 views

Can I use the unused brown wiring for my old thermostat for Nest Thermostat’s advantage? [duplicate]

Here are the images I figured out all the other connections as W/W1, Y/Y2, G, R & C but the brown wire is not connected to anything. What could that be for? Edit: From this answer I figured it ...
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5answers
16k views

Can I modify the vent from my high efficiency furnace to prevent possible damage to the exterior of my home?

is my high efficiency furnace vent installed properly? I'm based in Toronto, Canada. In some recent cold winter weather, the exhaust is causing a lot of ice buildup on the surrounding brick. To my ...
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1answer
42 views

wi-fi thermostat wiring for Carrier FE4 elec. furnace w/heat pump

what is the correct wiring diagram for a honeywell wi-fi thermostat on a carrier FE4 elec. furnace w/heat pump
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2answers
136 views

How to seal HVAC ducts running through old window to addition?

My house has a small addition that was added by the previous owners. They ran the HVAC ducts through an old window and some of the block: The rectangular section in the window should be easy ...
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2answers
411 views

G to C trick not working for cooling. Honeywell RTH9080WF

My electric furnace has no c terminal. Furnace is heat & cool both. (Lennox Electric Fan coil Model CBS18-21-3P). I installed Honeywell RTH9080WF. I switched G to C on my thermostat and got the ...
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1answer
159 views

Is there a wireless way to cut off the HVAC y wire from my generator transfer switch?

I recently had a Generac Synergy generator installed, which went smoothly, however there was no good way to get the Y wire from my thermostat to the transfer switch and back in order to allow the ...
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6answers
29k views

Does lowering the blower speed of a forced-air furnace lower its efficiency?

My gas furnace has two options for the blower speed: MED, and MED-HI. It had been set on the higher speed, but that was too harsh, so I lowered it to the slower speed. Does that have any impact on the ...
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1answer
141 views

Chattering contactor, what should voltage be when AC is on/off?

I have a Nest thermostat that I believe is the culprit of this issue. I've already replaced the contactor once and now the new one is chattering and not kicking the AC on. When the AC is turned off, ...
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1answer
6k views

Why is my furnace blower running at low speed?

My Payne gas furnace (PG8UAA 42091) automatically shuts down after it lights and burns for two minutes. It then gives a 33 fault code. I've done some research and some testing and have narrowed the ...
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5answers
23k views

How do I wire an old furnace motor so I can use it as a garage exhaust fan?

Since last I posted, I moved WAY south (lil warm down here) and the house I moved into was a foreclosure so a few things needed done, namely the AC and furnace. When the guy did the job he said he ...
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1answer
162 views

What should I do after a low-voltage wire was cut putting the furnace door back on?

I have the basic Honeywell thermostat that a lot of people have. All the thermostat wires go to the blower in the attic (for the central air). They are spliced with wires that then go to the furnace. ...
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4answers
1k views

HVAC supply vent noise: how to eliminate the whistling wind tunnel?

Every time the heat turns on (rented house), we are getting choked with too much dry hot air in our small room. When I try to close the supply vent it produces a really loud whistling noise. I either ...
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1answer
58 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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3answers
91 views

My Goodman a/c motor fails due to high voltage

I have got a brand new goodman unit. The motor kept stopping after few hours an the tech replaced the motor. It still had same issues.. I was told that the voltage coming into the unit is too high.. ...
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0answers
24 views

coleman furnace model dgaa furnace heats up and shuts down berfore blower starts and flashes code 4

york DGAA will work fine until it gets close to hot enough for the blower to turn on. I said close to turning on because I think it should get hotter but I'm not sure just guessing. The upper limit ...
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3answers
174 views

Is an HVAC license required for DIY home owner AC installation in the State of Georgia?

Does anybody know for certain if in the State of Georgia, an HVAC ("conditioned air") license is required in order for a homeowner to install their own HVAC system?
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2answers
2k views

How can I wire my WIFI thermostat to control my millivolt fireplace?

I have a gas fireplace that has an millivolt on/off switch on my wall (and a remote that includes flame on/off, a countdown timer and a thermostatic flame control). I want to be able to program ...
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1answer
134 views

Air Conditioning Drain Pump

I am going to purchase Multi-Split air conditioning unit for my apartment that I am fully renovating at the moment. So it is the right time to make wholes in the walls etc. The supplier is giving an ...