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

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1answer
150 views

Replacing Oil Furnace with Heat Pump

My wife and I would like to remove the older oil heat from our home and replace it with a heat pump. We currently have an Amana central air conditioning unit (3 ton), and an oil furnace in the ...
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1answer
77 views

Why is my AC blowing from this pipe and freezing up periodically?

I looked under my mobile home and found a hose coming from the flooring. It is blowing cold air out, and it also looks like water has been dripping out. I think that this is normal, but why is all ...
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1answer
407 views

Why did an HVAC installer add this PVC pipe?

We recently had a VERY old central heating furnace replaced and I noticed that the HVAC installer added the following PVC pipe shortly before the inspector arrived: The metal vents were already ...
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3answers
83 views

How to find areas where heat/coolness are lost?

I live in a 2-story rental townhome (basically an apartment with 2 stories). Our central air/heat system isn't really the best at keeping the upstairs and downstairs the same temperature whether in ...
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0answers
32 views

Is my heat pump's condenser fan motor bad? [duplicate]

The other day my AC stopped working. I'm thinking the condenser fan motor has gone bad (unit is ~10 years old). Here is what I did to troubleshoot which led me to believe it was the fan motor. ...
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2answers
444 views

Can I use an unused wire as a “C” wire?

I just bought a new thermostat that is Wi-Fi enabled and it requires connection to a "C" wire. The old thermostat does not have one running to it, but there are other unused wires. The thermostat ...
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2answers
84 views

Why is my AC suddenly *heating* my house?

I have a 13 SEER heat pump about one year old. Everything's been working fine, but the AC suddenly started heating my house spontaneously (no changes to thermostat, etc). The outside ambient ...
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1answer
38k views

What's the most common cause of AC coolant lines freezing?

I noticed my house wasn't getting under 75°F this weekend when I had the thermostat set for 70°F. Since I'd done a lot of drywall sanding inside recently, my first idea was to replace the filthy air ...
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2answers
1k views

Which terminal should I connect it to for a “C” wire when none are labeled “C”? [duplicate]

I am looking to replace my old battery operated thermostat with a new wifi model. There is no "C" common wire connected to my old thermostat. There is a blue wire that is at the thermostat but cut ...
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1answer
1k views

How to connect Nest in Europe

I found a question regarding the Nest thermostat here. But that is only a question "Will it work?". Thanks to that I know it WILL, the problem is...HOW. I know the wire naming conventions are ...
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0answers
49 views

How can I add a common “C” wire to my thermostat? [duplicate]

Possible Duplicate: Options for adding “C” wire to thermostat I recently bought the Honeywell THM5320R Wireless thermostat. After going to hook it up I found what many others have, it ...
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2answers
2k views

How can I use a separate transformer to provide a C wire to my thermostat?

I Purchased the Honeywell WiFi Prog Thermostat to replace my Round Digital Honeywell Thermostat. I have separate Heating and Cooling (Heating is a Weil McLain Boiler for Hot water baseboard and Hot ...
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0answers
266 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
92 views

sealing off sunroom to a/c in summer

what's the best way to seal off our sunroom so we don't pay to cool it? It's really humid AND hot in MS this time of year (avg 90+ F). We have a very "open" house, with a large dining room connected ...
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0answers
36 views

Refrigerant evaporator PVC condensate line is touching the hot air duct

My PVC condensate line coming out of the Refrigerant evaporator is touching the hot air duct coming out of the top of the heater. Is this a problem? A home inspector (for a buyer) saw it and said that ...
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1answer
223 views

A/C Condensation from duct getting into drywall

My A/C unit has ducts that run to the second floor, into the attic, to feed some ceiling vents. Today, after several days of brutal humidity, I noticed paint blistering, and in one spot bursting, ...
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2answers
161 views

How can I prevent my clothes dryer door from fogging up?

When I turn the air conditioning on in my house, the inside of the window in the clothes dryer door fogs up. Also, if clothes are left in the dryer, they become slightly damp again. How can I prevent ...
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1answer
1k views

Does a compressor with a short to ground really require a complete system replacement?

My 24 year old home A\C went out some time Sunday morning. I had a tech come out and look at it, and was told that the compressor is shorted to ground, and that this means I have to replace the entire ...
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1answer
379 views

Should I install a damper above my return air duct for better upstairs cooling?

I have a finished basement, ground floor, and upstairs. The ground floor and basement cool nicely with the AC. The upstairs doesn't cool very well. The returns are really just holes in the drywall- ...
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2answers
3k views

What could be causing an A/C blower motor to turn off randomly?

The Blower motor on my AC unit turns off at random times while the outside unit continues to run which is causing the coil to freeze up. The blower won't come on for 30-45 minutes after the AC has ...
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0answers
77 views

How do I troubleshoot my central A/C?

It's 79 outside right now. It's been running for hours and it's remaining 79 inside. I'm in a brand new 2 story home in Monroe, OH. It has rained a lot recently but I just feel like it should be ...
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0answers
151 views

How can I insulate and elevate an A/C line set on a flat rubber roof?

The Scenario An apartment building with a flat black rubber roof. The A/C condenser is on a platform on the roof with an air handler inside the unit. The line set runs across the roof for about 20 ...
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6answers
4k views

Would putting a sprinkler on my roof help cool my home?

Anyone ever put a sprinkler on your roof to help out your A/C on unusually hot days? Just wondering if it helps.
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2answers
851 views

Why does my window air conditioner cool but not dehumidify?

I have a brand-new 5000 BTU Frigidaire window air conditioner, and it seems to work fine except that it doesn't reduce the humidity in the room. I turned it on last night, and the temperature was 81 ...
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1answer
148 views

Why do they put an A/C vent in the utility room?

A related question is here about a year ago: Is there any reason to not tape this vent over? My question is, why do they put the vent there in the first place. Like the previous poster, I just bought ...
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1answer
64 views

Is it ok to stand atop my central A/C unit to install a missing soffit vent?

Unless I go on top of the roof, it's the only to get to it without a step ladder. I don't know if the covers on these things are meant to stand the weight of a 250lb guy. Aside from falling and ...
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2answers
420 views

What is going on with my central air?

I have a re-occurring issue with my central air. I have changed filters, cleaned all three intake vents and even had a serviceman out on three different occasions (two separate companies). My problem ...
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1answer
412 views

How well do whole house humidifiers work?

We are moving to an area where it gets cold and snows in the winter. We come from a desert area where it is never very cold except for the dead of winter, and where we use the heater very seldom. We ...
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1answer
145 views

What type of dryer best handles long exhaust vents?

I have a very long exhaust line (about 5 meters) from the dryer and have issues with moisture staying in it when I do laundry. Since the old dryer broke down, I am now shopping around for a new dryer ...
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2answers
1k views

What could be causing this leaky evaporator problem?

My apologizes if I do not know the correct terminology for some of the parts. I will try my best though. We have a Trane A/C system that is causing us a headache. It is causing water damage in our ...
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1answer
5k views

Humidity Levels

What is a healthy and safe humidity level that I should try to keep my house at?
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2answers
429 views

How do I improve heating in back room of house?

The back room of my house is quite warm in the summer. The room is on the north side of the house (Alabama, USA), so the outside walls don't get direct sun exposure. The attic insulation is a little ...
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1answer
112 views

Why does my blower fan sound like a yeti?

My A/C inside my house is making some kind of strange grinding noise. The fan wants to start, it blows cold air, and attempts to come on but only until whatever is making it drag stops the wheel fan ...
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3answers
460 views

How can I repair an air conditioner drain line that is broken flush with the wall?

As you can see below, I broke the drain line off flush with the wall. There appears to be either a union or an elbow embedded in the wall with a broken off piece of pipe in the fitting. The joint ...
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2answers
504 views

What type of air conditioner can bring in outside air?

Car air conditioners usually have the option to choose circulate on/off. What about house air conditioners? For instance, does a window air conditioner exchange air inside and outside the house?
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1answer
1k views

How do we replace an old 3-wire thermostat with a 4-wire one?

How do we replace an old 3 wire thermostat with a 4 wire one? We have an AC/heating unit, but the wiring for the thermostat does not have a yellow wire. What can we do?
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1answer
12k views

Why is my air conditioner tripping the circuit breaker?

Our air conditioner recently stopped blowing out cold air. When I went to check on it, I noticed that the outside unit wasn't coming on. We had had problems with ants in the contacter in the past, ...
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0answers
71 views

Why doesn't my A/C get power when using the alternate C-wire thermostat hook-up method?

I changed my old Honeywell thermostat for a new Honeywell WiFi thermostat. I installed it just as the directions stated. I used the alternate C-wire method as the old unit did not have one. ...
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1answer
411 views

Why won't the fan run independently of the air conditioner?

I have central air and heat, with a Nest thermostat. My system has Y, G, R, C and W wires coming out of it: which are wired into my Nest like so: In between, there is a splice where the C wire is ...
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2answers
235 views

Should we use A\C in the unused second story of our home?

We don't use the second story of our home. Is it better to shut off the air conditioning completely upstairs to save money, or keep it set but at a higher temperature, such as 78-80 °F?
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1answer
174 views

What is a quieter alternative to gas forced air heating?

My small 1BR apartment has an old gas furnace that works great, but costs my landlord too much to insure. He plans to install gas forced air, an in-unit upright furnace. I'd love to suggest a ...
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3answers
275 views

Would a normal ethernet cable survive the conditions in an air conditioning vent? [duplicate]

I am currently renting a flat, which prevents me from making modification to the walls. However, I still would like to run ethernet cables between rooms. Between all the rooms, there are AC vents ...
3
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1answer
240 views

Does outside air conditioning compressor fan run all the time?

Had some electrical issues with an air conditioner and after I rewired it, I noticed that the fan was stopping every 30 seconds or so. Is this fan supposed to shut off when unit is running?
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1answer
296 views

How can I get my thermostat C wire connected? [duplicate]

I have an older furnace, on the switch block I have Y,C.W,R and an unlabeled screw that connects to the shut off it looks like. I need to hook up a thermostat that needs the C wire. I have a spare ...
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1answer
115 views

What to look for in a new furnace

I've recently been told that my furnace, which is about 20 years old, is on it's last stretch and that I should consider replacing it now rather than waiting for it to fail - potentially at a very ...
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3answers
503 views

How can I repair these rusty electrical connections?

When I turn on my air conditioner at the thermostat the vents kick on but nothing outside. Also the last time that it worked it took a few minutes to get going and was pretty loud. I checked the ...
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4answers
523 views

What could be wrong with my air conditioner?

My outside fan (compressor?) will not turn on. I have a week or two before the weather gets warm so thought I would try fixing it before I hire someone. Symptoms - I turn on the air. The blower ...
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2answers
624 views

What could be wrong with my A/C unit?

I just installed a new compressor fan on my outdoor A/C unit. Before the fan went bad, it was working fine and had just had its annual service check (the service guy said the freon was fine, ...
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1answer
161 views

Exhaust venting into air return?

In the condo (2 story semi-detached townhouse built in 2004) I rent, the main bathroom has an interesting vent system. When turned on, 2 fans are activated. One is a booster of some type and ...
8
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1answer
241 views

Should I relocate the HVAC unit in my attic?

I have had a couple of estimates to replace our HVAC system and one contractor says he would relocate the system to a more central location in the attic. One says there is no need to relocate. There ...