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

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2
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1answer
246 views

HVAC electric thermostat panel “goes dead” and then live again all the time

I have this digital thermostat controlling my heater (gas). When I turn it on to lets say 66 deg, and the house is at 60, the HVAC will start working of course. Problem: After few minutes, the ...
2
votes
2answers
902 views

How do I repair loose ductwork?

The ductwork in our 30 year old house has started coming loose where it comes up through the floor. It's nailed to the subfloor, but in several places, the nails have come loose, leaving gaps of an ...
2
votes
1answer
106 views

Can I cap the air return in my unfinished basement?

I noticed today that there is a massive air return in my unfinished basement. The opening is about 2 meters from the blower, and as large in diameter as the return duct coming from the upstairs. This ...
2
votes
1answer
142 views

How do I connect a C wire to an Utica PEG112CDE steam boiler?

I want to upgrade my old mercury thermostat that I currently have to a newer programmable thermostat. This little DIY project is for my first late 1920's home that I recently purchased. I currently ...
2
votes
1answer
95 views

Why does my heat pump keep triggering the high-pressure cut-off?

Our Rheem heat-pump is on the fritz. It keeps triggering the high-pressure cut-off on the outdoor unit. We've had problems with this happening before, but only when the outside temperature got to ...
2
votes
1answer
130 views

Is my Heat pump and gas furnace installation incorrect?

I moved into a house about 2.5 years ago, and the previous owners had a heat pump installed, together with a gas furnace. Recently I had my furnace repaired (faulty igniter) and the HVAC technician ...
2
votes
3answers
386 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 ...
2
votes
1answer
143 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 ...
2
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0answers
218 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 ...
2
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0answers
118 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 ...
2
votes
0answers
80 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, ...
2
votes
1answer
4k views

How can I add a “C” common wire to this system? [duplicate]

I would like to add a "C" / Common wire hookup to my hvac system and get a fancy new thermostat. I've read Options for adding "C" wire to thermostat and still have some questions. First of ...
2
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0answers
158 views

Is mold growing in my ductwork? [closed]

I am currently in a battle with my landlord over what I believe to be mold growing on the fiberglass liner of the ductwork in my apartment. He is having a specialist come to test it tomorrow, and I ...
2
votes
0answers
530 views

What are good Relative Humidity and Temperature settings on an MHRV and are the settings related?

I need to configure the threshold Relative Humidity and Temperature settings on an whole house MHRV system. The way the system works is that if the RH threshold is exceeded the system increases the ...
1
vote
2answers
968 views

Is there a filter-reminder thermostat that uses run-time instead of total time?

My HVAC filter is in my crawlspace and is a hassle to change. I don't want to change it more than needed. "Change it every month" is bogus advice because in some months (like May) we don't have to run ...
1
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2answers
204 views

At what temperature does a WiFi thermostat stop sending a signal to the router?

I recently purchased and installed a Honeywell WP6500 WiFi thermostat and thanks to Stack Exchange, got it up and running. I have a house in New Hampshire, which I use occasionally during the winter. ...
1
vote
1answer
1k 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
3answers
490 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 ...
1
vote
1answer
4k views

AC Unit Blow Warm Air Indoor But Colder Air Outdoor

I have two AC Units. One for upstairs and one for downstairs. The upstairs one works just fine but not the downstairs. So, i did a test by turning both units on and went outside to compare the two ...
1
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4answers
1k views

How to fit 4" rigid aluminum duct vent in between walls when there is an angle brace?

I want to do what these people have done here: The problem is I have bracing going diagonally and it is not leaving enough space for the 4" aluminum duct vent. Can I saw the bracing off for the ...
1
vote
3answers
591 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
4answers
746 views

Is there a special low temperature thermostat?

I have a gas ceiling mounted furnace for my garage. I want to set my garage at 35-40° F (1-4° C). Is there a special thermostat to control furnace at that low temp? (I've seen one works as low as ...
1
vote
2answers
5k views

How do I connect a dryer to a dryer vent?

I just moved my dryer (gas) a couple feet to a better location in the basement. It is actually now closer to the existing dryer vent to the outside of the house. The previous owner has it connected ...
1
vote
2answers
179 views

How do I choose a furnace airfilter?

I have a furnace/air-conditioner that can support filters of various thicknesses: 1", 2", or 4". Filters are available in various MERV ratings. How should I decide which filter to use?
1
vote
2answers
279 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 ...
1
vote
3answers
87 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
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2answers
278 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 ...
1
vote
1answer
693 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, ...
1
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2answers
1k 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
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4answers
1k views

Are 5" thick filters for furnace/Central AC still available?

My furnace/AC was installed about three years ago. It uses 16" X 25" X 5" filters. The problem is when I try to find a replacement at my local home center: at Lowe's, Home Depot, (you name it), I ...
1
vote
1answer
57 views

Is this HVAC capacitor dead?

HVAC system stopped blowing cold air today. Last time it did this, we gave it a 2-3 hour break, in case it was over-heated, and it came back. Today, same deal, but no cold air after a few hours. I ...
1
vote
1answer
192 views

Air handler condensation draining problem

For the life of me, I cannot figure this out. My air handler and heat pump were installed in 2006 and work great. For the first summer since I've owned the home, condensation started to not drain ...
1
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2answers
56 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 ...
1
vote
2answers
1k views

What to do about different rooms in the house being a completely different temperature?

I moved into a 30 year old home last December. There is a problem with the HVAC. I have included a very crude drawing of the floor plan The problem is that I can't maintain a comfortable ...
1
vote
1answer
705 views

Which way does the air flow through my furnace?

Below is my furnace and I need to change the filter however I am unsure which way is the airflow direction. Red or Blue?
1
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2answers
3k views

Controlling separate heat and AC devices from a single thermostat

I have hydronic radiator heat powered by a gas furnace situated in one mechanical room of my house and a currently being installed central AC whose air handler is situated in another mechanical room ...
1
vote
4answers
2k views

How can I calculate the power consumption of an A/C unit?

I have an AC unit with the following specs: Cooling Capacity: 1260 kcal/h, 1.47kW, 5000 Btu/h Fan Motor Power: 0.034 kW Current: 0.155 A My question is how much power does this unit actually ...
1
vote
1answer
3k views

Why is my furnace blowing hot air outside through a PVC pipe?

I turned on my furnace and went outside and noticed hot air blowing out a J-shaped PVC pipe. Is it a vent or error that needs to be plugged?
1
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2answers
315 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?
1
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2answers
5k views

How do I replace a condenser fan motor in a central air unit?

The condenser fan motor on my central air unit has seized up (tried like crazy to turn it it, but no go). I'm not sure how old the motor is but I'm guessing it's original, so about 12 years old. I ...
1
vote
4answers
3k views

Are there efficient ways to provide combustion air to heating appliances?

In a previous question we established that there probably should be a vent between my utility room (which opens into the kitchen and living space in general) and the outdoors (in my case the attic, ...
1
vote
1answer
76 views

How do I reinstall round 6" duct pipe in my basement?

The 6" duct pipe was removed in my basement. I am trying to put it back up, but the pieces will not go together. The pipe is no longer round, and even when i try putting pieces together that have the ...
1
vote
3answers
298 views

Electric panel distance from windows and/or gas service entry

I can't find anything specific anywhere else, but what is the minimum distance a main electrical panel can be from a window when the panel is mounted on the outside of the house? Additionally, is ...
1
vote
2answers
61 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 ...
1
vote
1answer
648 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 ...
1
vote
1answer
566 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 ...
1
vote
1answer
230 views

Propane HVAC system - convert to use wood burning stove?

is it possible to remove the propane part of the HVAC and replace it with a wood burning stove? If so what would I have to change - eg the chimney etc etc?
1
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3answers
109 views

can I install a new thermostat by just turning off the power instead of turining off the circuit breaker?

Can I install a new thermostat by just turning the power off at the servicemen's switch, instead of at the breaker?
1
vote
1answer
35 views

Testing AC ductwork

I am about to bring in a contractor to install central AC in my house. I am in the final stage of a rather comprehensive remodeling effort, all of which was done either by me directly (cca. 85%) or ...
1
vote
1answer
837 views

Is it okay to connect a round supply duct directly to an air handler?

I removed all of my existing duct work that was designed as a radial system with a sheet metal rectangular plenum with very long flex runs poorly attached. I am replacing my system with all round ...