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

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1answer
22 views

Zoned oil furnace and AC thermostat question

I recently moved into a new home and wanted to replace the old thermostats with digital Honeywell ones. From what I understand the home has a Rheem 10 Seer (1996) compressor and a Williams oil furnace ...
0
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2answers
89 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 ...
3
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1answer
197 views

What material is allowed for a furnace room ceiling material?

What types of material, other than drywall, are acceptable by Ohio HVAC Code for the ceiling of a small furnace room which will: Have return air ducts (only) passing through it to attic space. Butt ...
2
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4answers
6k 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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5answers
8k views

How much cooling can I expect from a central air conditioner?

Yesterday's high was 106.0F, low of 79.2F, full sun all day. AC set at 78F, indoor temperature reached about 85F. Today's high was 105.4F, low of 81.1F, full sun all day, now about 102 at 7pm. AC ...
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1answer
25 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?
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1answer
14 views

Should I add an escape register for added ventilation in A/C duct to reduce condensation?

I have a condensation and drippage problem where my 8" exposed circular AC duct comes out of the ceiling. Above the ceiling is the attic, meaning it gets pretty hot. The pipe comes out of the ceiling ...
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1answer
100 views

Why does the blower in the attic vibrate during heating when it is really cold?

We have a Carrier heat pump system in our home, and the blower is located in the attic. When it is especially cold, the blower runs on high (there are three levels: high, medium, low). During this ...
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1answer
52 views

Can I remove my vent covers without disconnecting the duct?

I have an old house with flexible duct work in the ceiling. There is mold in at least one. Can I remove the vent covers to clean or will that disconnect the duct work in the attic from the vent ...
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1answer
21 views

What could cause a heat pumps line sets to be the same temperature when running?

The symptom I'm dealing with is that the heat pump system isn't cooling as much as it should. Tested it today, was about 79°F inside and outside; system was blowing air at about 73°F. ...
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1answer
32 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 ...
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1answer
84 views

Can a problem with heater stack liner cause outside chimney mortar to crack and fall out

I had "high-efficiency" furnace installed in 2009. In 2011 chimney required full grind-out and repoint job, and chimney saver solution was applied to prevent water damage. Service lasted only 18 ...
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1answer
27 views

Can I remove the insulation from flex duct

I am trying to fit a 7" flex duct between some floor joists and it would fit better without the insulation. Can I remove the insuluation and just use the plastic part?
0
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1answer
46 views

Foil tape failure in HVAC unit

On a recent trip up into my attic, I found out that the air conditioner was blowing cold air into the attic. In several places at the AC unit, the foil tape had become unsealed. In the interest of not ...
1
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1answer
132 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 ...
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2answers
42 views

What can I do to avoid tripping over HVAC drain line?

The drain tubes for the Furnace and AC run about 10 feet across the laundry room to the drain in the middle of the floor. Unfortunately this is a fairly high-traffic zone (seven people living in the ...
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2answers
34 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
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2answers
253 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 ...
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2answers
54 views

Running air handler condensate drain into sump?

The condensate drain from our air handler now runs across the wall and into the laundry sink. This is stopping us from attaching shelving to the wall. I noticed that the sump pump pit is right next to ...
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2answers
76 views

What are the possible reasons I am not getting cold air from my air conditioner?

my heat pump outside is working but my central air conditioning/heating unit in the garage makes a hissing sound or faint sound of water running. There is air coming from the vents. The very last time ...
8
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2answers
66k views

What's the most common cause of A/C refrigerant 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 ...
0
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1answer
53 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 ...
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2answers
52 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 ...
1
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1answer
47 views

Undersized AC - Options?

Background: Our two-story house is about 3,000 square feet. When we bought it last year, it had two separate AC units, a 2.5 ton and a 4 ton. They were both old and died last month. We had them ...
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0answers
25 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
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1answer
514 views

Wifi Thermostat wiring

Replacing 2 Hunter thermostats with a Honeywell RTH9580 Wifi. Neither unit has a C wire - I'm comfortable with the upstairs high efficiency unit, but the downstairs older unit has thrown me for a ...
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3answers
65 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: ...
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2answers
82 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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2answers
54 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 ...
0
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1answer
276 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 ...
1
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3answers
155 views

Does my crawl space need venting

I have a crawl space under my main entrance of the house. It's about 3' tall. I added a heat duct because the floor at the entrance was always cold. So my question is do I need to vent the crawl space ...
1
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1answer
135 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
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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.
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2answers
147 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
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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
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4answers
5k 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 ...
5
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2answers
976 views

How do outdoor mist-cooling A\C units fare in real-world usage?

I live in Phoenix where summer outdoor temperatures regularly exceed 110°F and humidity around 15% or lower is not uncommon. In this environment a mist system can easily pull the temperature down ...
0
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3answers
81 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
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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
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1answer
50 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
666 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
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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
440 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
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1answer
24k 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
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1answer
61 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
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3answers
33 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 ...
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0answers
41 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
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2answers
64 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
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5answers
13k 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
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0answers
16 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 ...