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

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4
votes
2answers
1k 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 ...
1
vote
1answer
171 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 ...
11
votes
2answers
12k views

Why is my Nest thermostat not working with A/C?

I installed Nest thermostat a few weeks ago, replacing an old Lux programmable thermostat (there was nothing wrong with it). I connected 4 wires (R,W,Y and G) to the Nest. But as soon as I'd ...
2
votes
3answers
1k 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 ...
2
votes
2answers
2k 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?
0
votes
2answers
4k views

How do I connect the common wire in a Carrier air handler?

I am trying to install a new wifi thermostat in my home and need to locate the common terminal for my air handler. I have a Carrier model FB4CNF030. It's a new construction home and I have the blue ...
1
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0answers
88 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. ...
1
vote
1answer
745 views

Can I convert a window A/C unit in to a pool-water cooled system?

I have an 18,000 BTU A/C unit that blew a compressor last year. Perfect for a small project. I however could not find a professional to help me out, so maybe it's DIYable. I know just about enough ...
2
votes
2answers
991 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 ...
8
votes
1answer
39k 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, ...
5
votes
3answers
89 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 ...
1
vote
2answers
338 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?
2
votes
1answer
325 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 ...
1
vote
3answers
741 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 ...
4
votes
5answers
24k views

Should I insulate air conditioner coolant pipes?

I recently replaced some rotted insulation on the coolant pipe that runs out of my AC unit and into the evaporator in my house. When cleaning inside the actual AC unit itself I noticed that the ...
3
votes
1answer
424 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?
2
votes
1answer
2k 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?
4
votes
3answers
3k views

How effective is a heat pump for AC and a heat pump/furnace for heating in New England?

We currently have a central AC unit and oil furnace. The AC is broken and the furnace is old, so we are thinking of replacing both sometime in the next year. We are considering replacing the AC with ...
2
votes
3answers
1k 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 ...
4
votes
1answer
859 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 ...
0
votes
1answer
257 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 ...
1
vote
4answers
1k 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 ...
1
vote
3answers
684 views

I need a multiple-switch light switch which can't all be turned off at once

I have a 4 switch (I think it's called "4-gang"?) light switch on the wall. It's not connecting to lights though, but to AC vent doors. Now, these AC vents must never all be closed at once. Meaning, ...
1
vote
1answer
98 views

Plug HRV (Constructo 2.0 ES) into power bar?

Would there be any issues if I plugged this HRV into a power bar? I have this unit (says 200 watts of power) which is in the closet of the master bedroom and plugged directly into a wall socket. I ...
1
vote
3answers
2k views

How can I add ventilation to my basement office?

I have a finished basement with an office, guest bedroom and bathroom. All about 700 sq ft. I work 12+ hours in the office and really need to get some fresh air circulating by extracting stale air. ...
0
votes
1answer
119 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 ...
0
votes
1answer
152 views

How can I add a relay to the manual control for my HVAC unit?

I have a self standing HVAC unit that has a control panel with manual buttons. There is no thermostat. Eventually my goal is to create a relay that can be controlled via IR/RF so I can install a Nest ...
3
votes
1answer
178 views

How do I install a bathroom exhaust system?

We are set to close on our house in about three weeks and one of the problems that the inspector noted was that the vent in the guest bath vents into the attic (never going outside) and the master ...
1
vote
0answers
1k views

How do I size a wall sleeve for a through-the-wall air conditioner?

We are shopping for a through-the-wall air conditioner. We do not currently have a hole in the wall with a sleeve in it. We are trying to figure out what sleeve to buy. The air conditioner we like ...
3
votes
1answer
106 views

Does code require the gas line to be replaced when replacing a furnace?

I replaced my 45 year old (still working) original furnace with an American Standard furnace about 5 1/2 years ago. Now I have a gas leak; the Nicor technician sealed a connection in the gas pipe ...
0
votes
1answer
441 views

Why isn't my thermostat working?

I have an old Lennox (gas heat only) thermostat. There are 3 wires coming from the wall. Black, yellow and a light blue color (could be a faded green or an old dirty white). The thermostat wouldn't ...
2
votes
2answers
781 views

Why does the pilot light on my Vermont Castings stove keep blowing out?

I bought a house with a sunroom heated by a Vermont Castings gas stove with a problem the HVAC/stove repair person hasn't solved by replacing the thermocouple, valve($$$) and taking apart and ...
3
votes
1answer
92 views

How do I provide proper fire protection in this situation?

HVAC guys are running a vertical duct (supply and return) from my basement to my 2nd floor attic. It will run adjacent to an exterior wall and will eventually be enclosed in a drywalled-in vertical ...
4
votes
2answers
958 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 ...
0
votes
1answer
394 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 ...
1
vote
2answers
196 views

Is it safe to install a heating duct register in the ceiling directly above a home entertainment center?

We're in the process of getting bids for central heating and one of the conundrums is where to position the registers. Due to the layout of our living room (and style preferences of my significant ...
2
votes
0answers
123 views

Does each zone in a two-zone heating system have its own pilot light? [closed]

I have two zone heating, in the basement and upstairs where we really live. The pilot light is lit downstairs, but the heat isn't working upstairs (the air is not getting hot). Is there also a pilot ...
4
votes
1answer
1k views

Where should carbon monoxide detector be located?

How many carbon monoxide detector is need in house and where it's more strategic to place it? Is it better to place it low close to the ground or high close to the ceiling?
1
vote
2answers
2k views

Can you terminate more than one common on the furnace C terminal?

TL;DR: Can you terminate more than one common on the furnace C terminal? Background: I've linked a diagram of how my non-programmable thermostat is currently hooked up. I want to replace it with a ...
10
votes
2answers
15k views

What does a Summer/Winter switch on furnace air ducts do?

On some of our furnace ducts, there is a switch/valve for Summer/Winter or S/W. What does changing this switch/lever accomplish? Can bad things happen if I forget to switch it? Bonus question: ...
0
votes
4answers
5k 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 ...
2
votes
0answers
88 views

Should I install the jumper on my new limit control?

I needed to replace fan and limit control (White-Rodgers, model 5D51-35), because the fan switch was broken (fan would constantly run) and heat would not stay on. I took a picture of the control, ...
0
votes
0answers
242 views

Why isn't water running through our radiators?

We had a plumber in today to bleed our rads. He also changed the batteries on the thermostat and fiddled around with the boiler. Since he left the temperature has dropped dramatically and he's refused ...
1
vote
2answers
2k views

Why is my furnace blower coming on so early in the ignition process?

Alright, I installed a new furnace a few months ago and have begun to notice an issue with the blowers. When the furnace first starts up, the exhaust blower should turn on to expel gas, then the ...
1
vote
2answers
4k views

Why does the air flow heavily from my downstairs vents, but very weak from my upstairs vents?

I live in a two-story townhouse where the first floor is ground-level on a slab. On the first floor, all air vents are either on the ceiling or at the very tops of the walls. Upstairs, the vents are ...
5
votes
7answers
23k views

How can I prevent my HVAC condensate drain line from freezing?

Last night, my heat (forced air) suddenly stopped. Today, a plumber figured out that my heater is 90% efficient, produces lots of condensate, and the drain line had frozen. We went outside and saw ...
1
vote
2answers
2k 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 ...
1
vote
1answer
221 views

What does the low limit do, and where should it be set on an oil fired hot water furnace?

What does the low limit do, and where should it be set? My furnace has a honeywell triple aquastat relay and has a difference dial. Water temp is about 190 deg F. Also, water psi gauge is only ...
1
vote
1answer
297 views

Why won't my propane boiler's pilot stay lit after replacing the thermocouple?

The pilot on my propane boiler won't stay lit for more than 30 minutes even after replacing the thermocouple and outside gas valves. The inside gas valve was replaced two years ago. Service people ...
1
vote
0answers
1k views

What's causing my draft inducer to stay on?

I have a new, 3-year old, high-efficiency, gas furnace in my home. I recently realized that my draft inducer, which normally kicks on before the burners and before the main blower, is not stopping. ...