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

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23 views

How to install small damper in a duct?

I need to install a Honeywell 10x10 damper into a 11x11 duct. Options that I came up with: build an adapter to reduce duct to 10x10 (alternatively I can use 12x12 damper and build adapter to ...
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1answer
131 views

Why isn't my Lennox G26Q3/4-100-6 furnace firing up?

I replaced the batteries, does not click when it calls for heat in the thermostat. fan blows but no heat. I took off inspection door, held the safety switch in, a blue light is blinking constantly, ...
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1answer
35 views

Wintertime and AC line frosted & dripping water in basement?

One line IS insulated in the exposed basement ceiling, so I am supposing this frosted & dripping line is the smaller return line? Have a dehumidifier running but the problem remains. What can I do ...
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0answers
49 views

Is there any problem with installing underfloor heating and wood flooring?

I have planned to renovate my home.I want to install underfloor heating system of Airdex for my home.I am planning to go with wooden flooring as well so will I face any kind of problems in future ...
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1answer
200 views

Fan coil wiring problem with new thermostat

I'm trying to upgrade to a new line voltage thermostat. The new thermostat has many more connections, including three fan speeds. My current system has a manual fan switch on the wall so all I need ...
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2answers
72 views

HVAC System Just Installed Yesterday and AC condenser outside is blowing cold ir

HI my just installed ac condenser is blowing cold air out side . when I put my hand over it and move it around most of the air is hot but a portion of it is cold. Is this right ?
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31 views

What could be causing my goodman furnance to not work?

My furnace starts, than the blower motor runs constantly, but trips out on roll out limit switch. The air inlet and outlet lines appear to be unobstructed, but when it shuts down there seems to be ...
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1answer
267 views

Why won't my thermostat control the HVAC anymore after trying to switch thermostats?

I bought a new Nest thermostat which is supposed to be compatible but needs a professional installation (advice that should have been heeded by non-professional electrician me). This is to replace an ...
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1answer
829 views

Connected C-Wire to new Smart Thermostat and Furnace board and still no power

I need help. I've been surfing the internet and have had no luck finding answers to my situation so am hoping for some guidance. I've seen other questions here answered but none that suit my ...
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2answers
307 views

Smart Thermostat - No C-Wire - No Controller Board

This one seems to be a little different from previous questions on the subject. Here is the dilemma, I don't see a transformer. I have included a few pics. There are Three wire bundles. For ease ...
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1answer
39 views

Aprilaire 700 humidifier not working properly

The fan does not seem to be running. How can I determine what the problem is? I'm not sure if it's the fan, solenoid or the computer board.
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1answer
190 views

AC not cooling using heat pump

I just bought a house and this is my first experience with using a heat pump. I have put in several hours of research and understand how it works but I need someone that has experience to give me some ...
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1answer
85 views

Trane furnace pilot wont stay lit

I have a 1983 Trane gas furnace, Model BLU108E936B1, the pilot light went out, I could get it to relight but wont stay on> Changed the thermocouple, same results, Pilot light doesn't look right as I ...
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0answers
24 views

Liquid line freeze up

Why would the liquid line on residential air conditioner freeze up during winter months, even though compressor isn't running? Have shut breaker off to assure outdoor unit isn't coming on.
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1answer
985 views

Can I have a separate thermostat for a wood boiler?

I want to wire a separate thermostat for my outdoor wood boiler so that just the furnace fan will come on without the propane kicking on. This is a Coleman furnace. Is this possible and if so, how ...
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2answers
101 views

What could cause my Carrier furnace fan to sometimes stop running?

I have a Carrier system: FURNACE 58UVB080; AC 24APA530, CONTROLLER SYSTXCCUIDO1-B, approximately 7 years old. New filter, impeccable condition. I was initially told by the licensed installers that ...
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1answer
80 views

Hvac fan runs and shuts off in a cycle when in heat mode

I have a Heil hvac model. N44336336GKE100, The system works ok when in cool mode but when in heat mode the outside fan runs for 30 sec then shuts off for 20 sec and continually repeats the cycle. I ...
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2answers
31 views

Gas Pilots going out

I have a unique problem with the gas pilots in my house. They all seem to be going out. One day I found both pilots in my fireplaces out. Didn't think much of it. I then found the pilot on my hot ...
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2answers
67 views

How does fresh air get inside a house with central heating other than through cracks of door or window on a cold winter day

I'm not sure how fresh air, or oxygen, gets inside my house other than through cracks of window or door on a cold winter day when the central heating system is on. I have a pipe that is coming from ...
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2answers
64 views

The house is not cooling

What would cause the outside ac motor to run than stop than start up again and continue this random stop and start cycle constantly. The house stopped cooling
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2answers
89 views

One portable air conditioner - want to use it in two rooms

I have a Kenmore portable air conditioner model - 408.72012. this particular model can be housed on the outside of the building and the A/C air is vented into the inside space (normally through a ...
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2answers
79 views

What is wrong with my air conditioner

I have been using my air conditioner on and off all summer. The weather hasn't been really that bad this year. But now that the weather is reaching high 80s, my air conditioner decides to die on me. ...
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1answer
78 views

How to Change Chinese HVAC Thermostat

I am looking to put Nest thermostats in the house, I have now found out my entire house (one in each room, 6 of them) has been wired with HVAC Chinese U12A UNIVERSAL A/C CONTROL SYSTEM urrgh – they ...
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3answers
372 views

Transfer Grille Baffle

I just finished building a new home and as part of the Energy Star rating transfer grilles were installed above each of the bedroom doors to allow air exchange when the doors are closed. The problem ...
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2answers
332 views

How to fill / seal in-slab hvac ductwork?

My house is built on a slab. Within the slab are "channels" which act as ducts for the HVAC system. I assume it is partially lined with metal but based on photos from an HVAC-cleaner, it's hard to ...
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2answers
88 views

Connecting condensate pump to sewer

My AC condensate pump currently pumps through a vinyl tube directly outside my house. However, I just replaced my broken home humidifier and realized that the previous one never had its drain properly ...
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1answer
28 views

Replacement part for coal stove blower rheostat

I have an Alaskan coal stove and my blower rheostat broke this morning. I opened it up hoping to be able to fix the part instead of buying a whole new fan controller. Any motor controllers that I ...
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1answer
49 views

Best Way to Heat a Tri Level Home

I have a tri-level home, which is approximately 1600 sq.ft. Presently I have electric baseboard heat, with a pellet stove on the main level. I am looking to upgrade to a better, more centralized ...
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1answer
24 views

Aprilaire 560 repair

My Aprilaire 560 humidifier will do a bang click many times before it turns the blower on. I replaced the solenoid valve with a new factory part and it still does the same thing. What next?
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2answers
3k views

Installing Honeywell WiFi Thermostat

I am trying to upgrade to a programmable thermostat. I bought the Honeywell RTH9580 with WiFi. I can get power to the new thermostat and get the fan running. However, it will not work when the fan ...
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1answer
49 views

Home Air Conditioner Problem

Hi I was wondering if you could help me. I have an air conditioning unit that was here when I bought the house. It was in the 70's here today, but I have an old house and windows don't open so the ...
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2answers
36 views

Why is my booster fan pulling cold air from outside?

This is my first winter in a house with an oil-heated, forced air system. I noticed my wall vents were pushing out warm air, but the floor cold air return vents were pushing out cool air. I followed ...
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1answer
24 views

Is ice on ERV door normal?

My ERV is forming ice and condensation on the top of the door and on top of the unit (presumably because the fresh air intake is on that side). The outside tempersture hit about 1 degree F today. ...
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3answers
7k views

What could cause a flame sensor to stop working so frequently?

Over a year ago after a month in our new house, we came back one evening to a cold home and after some googling, I found out that the flame sensor was dirty and the furnace was starting the flame and ...
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1answer
32 views

water coming down pcp from ceiling to furnance

water comes down the pcp pipe and overflows at the elbow. water seems to come even when the furnance is turned off. had a furnance man come out. he said there is a leak at the roof, as it had been ...
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1answer
41 views

what is the cause whereby compressor working gets hot and stops, after cooled down picks up

My challenge was that, I have this refrigerator I'm working on and after awhile it is working and then the condenser become hot as the compressor discharges excess heat, which as time goes on ...
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3answers
8k views

Does a whole house humidifier go on the intake or outlet of the furnace?

On what side of the furnace do I install the tank of the humidifier (the warm side or the return air side)?
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0answers
35 views

How to remove ice buildup from window air conditioner

My fan froze on my AC unit in my bedroom window. I was able to move the inside one when it froze, but this one is on the outside. Should I spray hot water on it to get it to move? I was going to use a ...
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1answer
704 views

How can I add a C-wire to a Venstar T5800 thermostat?

I am trying to replace my existing thermostat. My old thermostat has: Rh, W (coming from the heating unit). Rc, Y, G (coming from the AC unit). On the Venstar T5800, I can map as follows: Rh+Rc ...
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1answer
2k views

why does my heat pump wiring diagram show 7 wires going to the thermostat but the thermostat only says it needs 5?

Here is a link to the wiring diagram for my heat pump. The thermostat that I am planning on buying has the following terminals C, G, Y, O/B, RC, R, Aux, E, and L. The instructions say to jump the RC ...
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1answer
33 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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5answers
16k views

Why would my Goodman gas furnace start but not stay on for more than 2-3 minutes?

I've got a problem with my 15 year old Goodman furnace. It starts w/o problem, inductor begins working, hot surface ignitor lights up and ignites the gas. Then the main blower starts working and the ...
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1answer
35 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
59 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
57 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
3k views

Why would said gas furnace keep shutting off?

Seems that I have a gas furnace that is having some sort of heat/air sensing issue. Basically it shuts off after running for a minute or two. But if I remove the top plate of the furnace itself it ...
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1answer
45 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
5k 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
76 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 ...