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

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2
votes
0answers
65 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, ...
4
votes
3answers
2k views

Why does the pilot light go out when the furnace is running?

Every time the furnace fires up, it blows out the pilot light. Sometimes it will run a full cycle and blow out when it shuts down, and sometimes it will blow out about a minute into the cycle. We ...
4
votes
1answer
2k views

What would cause my furnace to only work with the filter removed?

My Carrier furnace works fine without the air filter in place on the return. With the filter in place it works for a while and then stops with a complaint about "limit, or flame rollout is open" ...
3
votes
2answers
2k views

What would cause a furnace to shut off prematurely?

I've got a Carrier Weathermaker 8000 furnace that shuts off about 90 seconds or so after ignition, started doing this recently. I get flashing code "33" which indicates: The code indicates: 33 ...
3
votes
2answers
372 views

What is this name of this vent attachment next to my furnace?

What is the name of this silver vent attachment thing at the bottom of the picture? It is attached to the side of our gas furnace. The black part is an insulated air duct which goes to a vent ...
0
votes
2answers
104 views

Connection for range hood from 8“ circular to 10”x3.5" rectangular

I am installing a new range hood for our kitchen. The duct exhaust at the top is 8" circular, but our old vent to outside is 10"x3.5" rectangular. I see what we could usually use a register boot but ...
2
votes
4answers
7k 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 ...
0
votes
1answer
38 views

air conditioning system stays on even when we turn off our thermostat

Our A/C system stays on even when we turn off our thermostat. What should we do to try to fix it?
0
votes
1answer
87 views

Air Conditioner woes: water pooling in basement, condensation on ducts, frost on outdoor copper pipe

Can someone help diagnose what's wrong with my air conditioner? The symptoms are: the air that it is blowing is not very cold It's colder than the ambient air, but not cold enough to cool the ...
1
vote
2answers
43 views

What are the external airflow requirements for portable and window AC units?

I have a window well in a basement where I'd like to setup a portable AC unit (~10000 BTUs). There is a cover that I need to keep in place to avoid water collecting in the window well, but I could ...
3
votes
2answers
351 views

How can I calculate the Btus needed for a single room A/C unit?

How many Btus is recommended for a room about 35 square meters? I have 2 units with 13,000 Btus each. I'm thinking it should be enough, but the room is just so-so cool. I can never say it's COLD in ...
0
votes
1answer
60 views

AC unit (turned on year round) leaves so much ice in the blower causing no cooling (pic included)

My mother has asthma and tells me she needs the AC on almost year round. The AC unit is outside the condo we own, and it connects to the coils in the heater/ventilation system. We are experiencing ...
0
votes
2answers
65 views

What size A/C unit should I install?

currently using a Goodman 24000 BTU Central air, installed in '96. it is starting to cost too much because of leakage of refrigerant. I did the size calculator thing and it recommends a 30000 BTU ...
0
votes
0answers
41 views

How can I install a floor register in bathroom

I need to install a floor register in my bathroom (which I am currently remodeling). I plan to put one into the floor under the window where it used to be. The old register came up through the floor ...
1
vote
3answers
72 views

Swapping out circuit board on York AC?

I have a York AC unit where the circuit board is shot, so I bought a replacement circuit board (same model). The model number for the board is 031-00251C. Pictures of old circuit board: ...
1
vote
2answers
106 views

What could be causing my A/C not to come on?

I had a thermostat get hot and smell, replaced thermostat. Still not working found fuse on control board blown replaced fuse. Lights on control board indicate no problems. Replaced 18/5 cable from ...
1
vote
1answer
254 views

How should I evaluate my central A/C to see if it's working properly?

I was once told by a service tech that they evaluate how well the system is performing based on temperature difference between the the return and supply sides. On our first really warm day (80F+), I ...
4
votes
7answers
5k 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.
1
vote
2answers
191 views

Is a little ice on the cooling coils ok?

This is our first summer in a new house which has central air. It was a bit hotter today than normal so the AC was running for a long time. After awhile we noticed the airflow stopped because the ...
2
votes
2answers
5k views

Are there any ductless mini split systems that offer standard HVAC wiring controls?

Have been looking for in the US a ductless mini split heat pump system something like the Mitsubishi Electric Mr. Slim that uses a non proprietary wiring scheme for its wall mounted thermostats. ...
3
votes
4answers
6k views

How can I connect two indoor ductless A/C's to one compressor?

I have one Hitachi i-clean split AC 2ton unit installed in my home. I want to connect another indoor ductless unit to the already installed outdoor compressor. I only need to use one indoor unit at a ...
0
votes
3answers
113 views

A/C Runs non-stop and shuts down without reaching desired temp

I have had a repair man out 4 times and he says he can't find anything wrong with the unit. I cannot even feel air coming out of the diffusers unless I climb on a chair and put my hand right next to ...
14
votes
4answers
9k views

Why don't programmable thermostats automatically switch between “Cool” and “Heat”?

While I can set my house to be a particular temperature, I still have to manually switch it between "Heat" and "Cool" mode, and this seems to be true of every thermostat (programmable or not) that ...
1
vote
1answer
75 views

What causes a HVAC control transformer to overheat?

I recently replaced my 24 volt HVAC control transformer. The outside unit started up including the air handler and ran for maybe 10 minutes. After the units shut down I noticed that the transformer ...
8
votes
4answers
699 views

What type of regular maintenance should I be doing on my central air conditioning unit?

I have not done any maintenance on my central air conditioning system since I bought my house five years ago. Everything seems to be running fine but is there some sort of maintenance I should be ...
4
votes
2answers
2k views

What are these two pipes coming out of the house?

I am trying to figure out the purpose of a couple of pipes that are currently coming out of the house. First, a couple of notes: One-story house. HVAC system is in the attic. It is winter here. ...
3
votes
2answers
465 views

Is there a trick to getting round HVAC duct pieces to fit together

I have been doing some basic HVAC duct work as part of a remodeling project and I can never get the pieces to fit together without massive amounts of elbow grease and mangling the ends. Is there some ...
6
votes
1answer
28k 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, ...
0
votes
1answer
85 views

Can I fill this AC line inlet with expanding foam?

I think the PVC inlet for my AC lines is a possible entryway for mice getting into my attic. Is there any reason I shouldn't fill it with expanding foam to seal it off? Or is there a better, less ...
0
votes
3answers
38 views

Will high efficiency furnace plumbing lead to cold air entering the house?

At the outside wall of my house I can see two white PVC round tubes/pipes, I understand one is for sucking air from outside, and one is for furnace blowing warm air to outside - correct? We are ...
1
vote
0answers
53 views

Dust reduction and removal?

I have a room with west facing windows (I dont think the direction bears any importance to this question), but for some reason this room seems to accumulate dust on surfaces a lot faster than other ...
0
votes
2answers
70 views

how do I keep leaves and foreign objects out of the top of my a/c unit?

Is it possible to make a lid that is light enough for the air coming off the fan to raise it attached with hinges so it drops back down when not in use. This would keep debris from getting inside, yet ...
4
votes
5answers
16k 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 ...
0
votes
0answers
17 views

Is my vent cap big enough for my vent hood?

I have installed a 900 CFM island vent hood. It works properly, but it doesn't vent as quickly as I would expect. The ducting is only 18" and straight out (and up) through the roof, so that's not ...
9
votes
9answers
10k views

Do thermostat-controlled, auto-adjust HVAC vents exist?

The residential forced-air HVAC systems I have seen are controlled by a single thermostat in one room. One has to manually adjust the vents in order to adjust the temperature in other rooms. Is ...
0
votes
0answers
88 views

What could be causing our air conditioner circuit breaker to keep tripping?

Our air conditioner circuit breaker marked "AC", is tripping frequently after the AC unit works for a while. Sometimes as long as an hour or more and, sometimes as short as few minutes. We were told ...
0
votes
1answer
154 views

How well does a single A\C unit provide 2 zone cooling?

My 2,900 square foot house currently has two separate AC systems (one upstairs, one downstairs). They're both very old and need to be replaced. One of the four HVAC salesman that provided quotes ...
0
votes
3answers
218 views

Can I wire a Bathroom Fan to two Switches in Parallel?

I want to control a bathroom exhaust fan with a wall timer, and a 24 vac relay. Basically both switches would be wired in parallel. Is this safe to do?
9
votes
5answers
1k views

Why won't HVAC supply stores sell directly to the public?

I am quite shocked that every store in my very large metropolitan area that sells HVAC supplies requires purchasers to have HVAC contractors license. Which makes it very difficult for a very ...
0
votes
2answers
384 views

Can I install whole house humidifier in AC ducting?

Just grabbed 2 Honeywell whole house humidifiers: HE360A1075. It's the best model Lowes has and recommends. I have 3 floors and a basement in an old (1890s) victorian house. We have cast iron ...
1
vote
1answer
860 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, ...
1
vote
1answer
95 views

How to maintain temp for always cold office in finished Basement

I work out of my home in an office in our finished basement. The room is always cold whether it's the middle of winter or the middle of summer. I often run a cheap space heater (especially) in the ...
0
votes
1answer
646 views

Need help running and connecting a 'C' wire to my new thermostat

I have a Laars gas boiler that has 3 heating zones; basement, 1st floor, and 2nd floor. I want to replace the old mercury honeywell tstats on the 1st and 2nd floor with newer honeywell RTH9580 wifi ...
0
votes
1answer
282 views

How should I attach a C wire on my chromalox boiler?

I have a chromalox canada boiler model EDB-2. Recently I purchased a wireless honeywell transponder and thermostat, and am trying to install them. I currently have W and R wires but am missing a ...
0
votes
3answers
41 views

Can forced central air be retrofitted with central humdifier?

Several homes I'm considering have central air conditioners, but radiators or baseboard heaters. Is it possible to use the A/C ductwork to provide humidity to the home? I assume most central ...
1
vote
0answers
20 views

How can I reduce the noise from an HE boiler vent?

I have a HE boiler that is direct vented out the side of my house on the neighbors side, they find the 'roar' of the exhaust to be very annoying. Have anyone tried troubleshooting these to ...
0
votes
2answers
92 views

How to Calibrate a Make-Up-Air Controller?

My home is equipped with a make-up air line intended to bring some outside air to mix it with indoors air prior conditioning by the furnace. I am not sure why this is necessary but my question is ...
4
votes
2answers
75 views

Resources for designing new HVAC [closed]

Our house is a bungalow with full basement and is currently heated via electrical baseboard heaters in every room. I'm converting this to a central air system heated by a gas furnace, and possibly ...
0
votes
1answer
76 views

Should I remove existing drywall before framing a wall around HVAC ducts?

My friend has soft AC ductwork running up an interior wall. He wants to build a wall around it to hide the ductwork. My idea is to pack out the wall by nailing in framing between the ductwork right ...
0
votes
1answer
319 views

Quieting cold air return vent

My gas furnace is in a dedicated "closet" inside the utility room. The closest cold air return is about 5' away (laterally) in the ceiling of the hallway right by the bedrooms. When the furnace ...