(Heating, Ventilating, and Air Conditioning) For questions about installing, repairing, and troubleshooting HVAC systems.
16
votes
1answer
1k views
13
votes
4answers
4k 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 ...
12
votes
6answers
495 views
Is it worthwhile to have ductwork cleaned?
Was rearranging some ductwork in my basement, and noticed that the stuff I took down was pretty filthy inside (especially the return air ducts).
Is it worthwhile to have ductwork cleaned out? What ...
11
votes
3answers
2k views
Ethernet cable instead of Thermostat wire?
I need to pull new wire from my furnace to my thermostat and was wondering if there would be any problems in using an Ethernet cable instead of standard thermostat wiring.
The reason being is I have ...
10
votes
11answers
4k views
How can I increase the heating efficiency of a forced air system?
What are some DIY ways to increase the efficiency of a forced air heating system?
Please answer in Community wiki fashion: 1 tip per answer.
Edit:
As @Jay Bazuzi pointed out, tips can also include ...
10
votes
3answers
3k views
Is running ethernet cable through an air return allowed under US code?
I'm looking to wire up the second floor of my house and the cold air return provides a convenient, straight run from the office to the utility room. Is it safe and within code to run ethernet cable in ...
9
votes
3answers
11k views
What are the pros and cons of a whole house humidifier?
In the winter, my house (~2500 sqft) becomes unbearably dry. Last winter, my wife and I used a tiny humidifier for the master bedroom to keep us from completely drying out, but since then I have been ...
9
votes
5answers
2k views
How can I calculate how large an airconditioner my house needs?
I know there are a lot of possible factors that go into determining the size of the air-conditioning system a house needs. Is there a standard way of calculating what is needed, or do A/C companies ...
9
votes
4answers
6k views
Does lowering the blower speed of a forced-air furnace lower its efficiency?
My gas furnace has two options for the blower speed: MED, and MED-HI. It had been set on the higher speed, but that was too harsh, so I lowered it to the slower speed. Does that have any impact on the ...
8
votes
8answers
4k 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 ...
8
votes
2answers
469 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: ...
8
votes
1answer
439 views
How do you trigger the hvac with wiring only?
I have a HVAC that has the usually wiring C R G W Y
Pinouts
What wires do I need to connect to turn on Heating?
What wired do I need to connect to turn on the A/C?
Is there a risk of damaging any ...
8
votes
1answer
146 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 ...
8
votes
2answers
430 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 ...
7
votes
3answers
1k 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 ...
7
votes
3answers
453 views
How can I reclaim heat from an enclosed furnace room?
Our home has two furnaces (oil fired hot air) and an electric water heater in an enclosed room (approx 6'6" x 9'). Three walls of the room divide it from the remainder of a finished basement, the ...
7
votes
5answers
5k views
Where should my furnace filter go in a Lennox G40UHX series furnace?
I have a Lennox G40UH(X) series furnace, which is installed in our attic (We have a single-story house on a slab). Because the furnace is installed in the attic, it is "laying down" on its side, and ...
7
votes
1answer
1k views
Why are almost all of my house's HVAC floor registers placed near exterior windows?
My current house is a single story built over a crawlspace and all the HVAC registers are in the floor. In all of the larger rooms, at least one (and usually more) register was placed near an exterior ...
7
votes
3answers
794 views
Are new “low noise” whole house fans actually quieter?
I've dealt with a number of older whole house fans (10 years and older) and the one thing they all had in common was a ton of noise.
Are the new "low noise" fans actually that much quieter than the ...
7
votes
2answers
376 views
Is there any legitimate reason to have a direct vent between utility room and attic?
I've been doing some sealing and insulating in my attic, and discovered a purpose built vent directly from the utility room into the attic space. See most of these photos
The house is in a ...
7
votes
1answer
392 views
AC issues / Insulation of vaulted ceiling
Issue: If it's hot outside, ~90F, house temperature can't get below 79F.
Background: 6 year old house, vaulted ceiling with 1 ceiling fan in family room where thermostat is (also 3 large windows, ...
6
votes
7answers
1k views
Should I apply car wax to the outside of my air conditioning unit?
Through different conversations with family members and friends, I have been told that it is good to apply a coat of car wax to the outside of the air conditioning unit frame. I assume that this is to ...
6
votes
4answers
1k views
Why aren't Geothermal heat pumps more common?
Air conditioning and heating are major energy consumers in American buildings - commercial, residential, and industrial. I have been curious for a while as to why it isn't more common to use the ...
6
votes
4answers
731 views
Heating/cooling system recommendations for this small house?
I will soon build my first house and I need to choose what type of heating/cooling system I'll have installed. I know very little about this and I'm seeking recommendations, ideas, suggestions, etc.
...
6
votes
2answers
6k views
What are the pros and cons of two AC systems vs a dual zone system?
I have a Cape Cod with 1000 ft2 on the first floor and an apartment in the attic. In a few years I may get rid of the apartment and build up a second story + attic. Both the first floor and the ...
5
votes
4answers
205 views
How can I keep a bedroom warmer in summer?
The master bedroom in my parent's house tends to be the coolest room in the house, and my father complains it's too cold. The A/C register in the ceiling does have a flow adjustment lever, but it's ...
5
votes
3answers
744 views
How can I determine why my A/C runs all day?
I have a Bryant AC/Furnace unit. My house is 10 years old. A heat wave hit this weekend & temps got up to 95°F outside. I had my thermostat set to 75°, and it ran all day. The ...
5
votes
2answers
420 views
When insulating with closed-cell Spray Foam, what ERV and HVAC resizing considerations should I bear in mind?
I am building a 2800 sqft, two-story brick home in Austin, TX. I have heard many good things about the benefits of insulating with closed-cell Spray Polyurethane Foam (ccSPF)1, and have requested ...
5
votes
2answers
434 views
How to best keep floor vent by shower dry/mold free?
We just moved into a rental home. It turned out after living there for a few weeks that we discovered the vents were innudated with mold. They were so bad the landlord had to replace all the vents in ...
5
votes
2answers
2k views
How do I install a wood stove as an auxiliary heat source?
I have a house with a forced air electric furnace.
We've also got a wood-burning stove adjacent to the furnace. I didn't have it installed, and I want to understand if it's been done properly, and ...
5
votes
2answers
224 views
Is it safe to install a sconce light box inside a return air space?
In my finished basement, the space between one section of studs is being used as a return air duct for my furnace and central air.
Here is a picture, looking up from the vent at the floor level:
...
5
votes
2answers
2k views
HVAC vents - does wall or ceiling mount matter?
I'm going to add some crown moulding to some bedrooms. I've got HVAC vents mounted near the top of the wall and the moulding will cover part of the vent.
I want to move the vents out of the way. I ...
5
votes
2answers
2k views
Is it OK to have heating registers and returns near the ceiling?
I've got a question about a new house - a friend of my mother's is buying a new place and when she did a walkthrough (before the drywall was up), she noticed that all the heating registers and returns ...
5
votes
2answers
376 views
Should I be concerned about fridge/freezer airflow?
We just recently had the following counter/cabinet system put into our basement family room. After everything was done, I started to get concerned about airflow. The enclosure was built in such a ...
5
votes
3answers
103 views
What concerns should I have installing a HVAC unit and ducts in a home that's never had it?
We're looking at a house in southern Alabama that has no central heating and air. I would like to put one in. The house was built in 1950.
What should I be considering about the installation?
5
votes
1answer
2k 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 ...
5
votes
1answer
332 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 ...
5
votes
1answer
111 views
Does lack of zone control delay hurt heat pump?
I had a new HVAC single heat-pump system installed with dual zone controls:
2 thermostats and 2 dampers for separate zones.
The system works, but the zone control board does not have any time ...
5
votes
1answer
437 views
Do I need to increase my HVAC trunk line size?
I'm thinking of finishing my basement. I currently have a main trunk coming off my furnace that measures 20" wide by 6" tall. I'm trying to future proof my home in the event my current furnace can't ...
5
votes
1answer
172 views
Is it possible to recover waste heat from a boiler?
I did a google search and came back with industrial products, but no residential prosucts.
I have a System 2000 boiler and hot water tank. When the furnace is firing, the temp of the exhaust through ...
5
votes
1answer
407 views
Is there a wireless thermostat that will make relocating easier?
I've got a single zone which covers all three upstairs bedrooms in my home and the thermostat is located in the master bedroom. We prefer it to be somewhat cooler at night, but the baby in the ...
4
votes
3answers
283 views
Advice for replacement/repair of an HVAC with a cracked heat exchanger?
My townhouse has a downflow 1994 Rheem 2.5 ton HVAC unit on its roof (combines both A/C and heat). We have had two issues with the unit and have been in the townhouse for a little under two years. In ...
4
votes
2answers
2k views
Can I run heating duct work through the attic?
Problem...
(in Buffalo NY)
We just about finished remodeling our master bedroom. Everything insulated, drywalled and we're living in it.
Now that the winter is upon us, we're already finding this ...
4
votes
2answers
266 views
Do joints in adjustable duct elbows need to be taped?
Do the joints in adjustable duct elbows need to be taped as well once they're adjusted or are they considered air-tight?
4
votes
2answers
429 views
Are there high flow floor heat registers available?
The weather has been pretty warm lately so we've been running our A/C. I noticed that it didn't seem like much air was coming out of the registers, so I checked to make sure the blades/louvers were ...
4
votes
1answer
776 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" ...
4
votes
2answers
101 views
DIYer to skilled tradesperson
What is the process a DIYer has to go through to become a skilled tradesperson? Are the only options apprenticeships, or are there other paths to follow to learn a trade/become licensed?
What type ...
4
votes
3answers
738 views
Is an interior laundry room without an HVAC vent a code violation?
Currently looking at a home which has a nice 2nd floor laundry. Vented dryer, nice rack for hanging clothes, etc.
However, it's in the center of the home and does not contain an HVAC (central air) ...
4
votes
2answers
657 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. ...
4
votes
1answer
638 views
Can I reroute this air duct?
I'm quite new to dealing with HVAC duct-work.
We would like to install a suspended ceiling in this room. Since the finished ceiling will be higher than this duct-work, we're going to build drywall ...
