Questions tagged [hvac]

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

Filter by
Sorted by
Tagged with
91
votes
7answers
503k views

How can I add a “C” wire to my thermostat?

So, the spiffy new wi-fi thermostats want power on the C wire from thermostat, but the old thermostat doesn't have a C wire at it. What's the easiest way to add the C wire/24 volt to the thermostat ...
10
votes
2answers
92k views

How do I identify the C terminal on my HVAC?

How do I identify the C terminal on an HVAC, furnace, or boiler? If the terminals don't have a screw labeled C what should I look for on the wiring diagram? What steps should I take if a wiring ...
20
votes
4answers
377k 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 ...
3
votes
2answers
15k 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
7k views

Why are the white and orange wires both connected to my thermostat's W terminal?

I wanted to get a programmable thermostat, but when I look at the wiring of the existing thermostat I’m not sure why the white and orange wires are both going to the W terminal. Other thermostat ...
5
votes
7answers
8k views

How to Lower the Ouptut of Oversized Furnace

Questions I would like to lower the output capacity of my furnace if possible. How can I do this? Is it worth doing, or should I just live with it? Is there an easy way? Some ideas: replace burner ...
3
votes
6answers
22k views

Air Conditioner Can't Keep up

We just rented a condo and our A/C cannot keep up so it will run almost constantly. It can't even keep the temperature constant, it will creep up into the 80s even while running. I measured the ...
2
votes
2answers
7k 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 ...
18
votes
10answers
29k 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 ...
11
votes
1answer
114k 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, ...
8
votes
6answers
105k views

How often should I run a bleach and water solution through condensate lines?

How often do you need to run a bleach and water solution through the condensate drain lines (of a heat pump) to keep the bacteria away? What are the recommended parts (e.g. 1 part bleach, 10 part ...
7
votes
2answers
6k views

Can an HRV replace the air exhausted by a range hood?

I'm in the process of buying a 1950s ranch house. It doesn't have the greatest insulation, so I'm planning to do some improvements over the first few years to tighten things up. I'll certainly do the ...
7
votes
2answers
9k views

How do I install a jump duct?

Our master bedroom is considerably warmer than the living/dining/kitchen area of our house, and we've been setting the thermostat quite lower than we'd like in order for the bedroom to get cool enough ...
4
votes
14answers
42k 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.
4
votes
1answer
9k views

Convert line voltage heating system to use low voltage thermostats

I currently have two line voltage ceiling radiant heating systems in my condo each with their own DPST thermostat. I'd like to use low voltage thermostats such as the nest. I found this transformer/...
3
votes
8answers
57k views

How can I use a separate transformer to provide a C wire to my thermostat?

Update 02/02/2019 I appreciate all the responses and help but unfortunately i must have not seen the emails stating there were responses! I am now looking into a NEST thermostat and was curious if ...
9
votes
5answers
106k 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 ...
4
votes
4answers
929 views

Air conditioning on a shoestring budget

Without purchasing expensive air-con units, or solar panels - and the associated moutings and electrical paraphernalia, is it possible to create a temperature difference of 10-20 °C using materials ...
1
vote
0answers
25 views

U.s. boiler / Burnham boiler alterations

i have a 203ncl-tei2 boiler installed in danvers Massachusetts. Regular elevation. This boiler also has a failed tejurland (universal control) powerventer motor on it that is only humming, not ...
5
votes
2answers
2k views

Will pipe insulation stop condensation on an HVAC drain line?

ISSUE A sweaty condensation drain line is dripping and causing mold in a ceiling panel: The condensation drain pipe is lengthy and spans two rooms: QUESTION Is insulating the pipe an effective ...
4
votes
1answer
15k views

How should I wire this White-Rodgers fan and limit control? What about the thermostat?

I have a wood-burning stove, that is used as an auxiliary heat source in the house. There's a regular electric furnace, and adjacent to it is the stove. The warm air duct (out) from the stove ...
3
votes
2answers
177k views

Why do the evaporator and suction lines freeze when there is low refrigerant?

In an AC, why does a low refrigerant condition cause the evaporator, and/or suction line, to freeze up?
2
votes
1answer
4k views

Should I install a damper above my return air duct for better upstairs cooling?

I have a finished basement, ground floor, and upstairs. The ground floor and basement cool nicely with the AC. The upstairs doesn't cool very well. The returns are really just holes in the drywall- ...
1
vote
0answers
747 views

Putting a window air conditioner into an awning window

I bought a window air conditioner thinking that I could alter my awning window to accommodate it. I have since discovered that I can't remove the part of the window that swings out or alter it so that ...
1
vote
1answer
486 views

Heat vent found under dishwasher

So we purchased a brand new home in June 2016 and found the builder put a heat vent under the dishwasher. He explained it's pretty normal but after asking HVAC pro's, it isn't. My question is, ...
0
votes
3answers
763 views

One portable air conditioner - want to use it in two rooms

I have a Kenmore portable air conditioner model - 408.72012. this particular model can be housed on the outside of the building and the A/C air is vented into the inside space (normally through a ...
0
votes
0answers
72 views

Portable air conditioner question

I've picked a portable HVAC unit. It's a 2.6 KW 10,000 BTU model. The only way I will be able to vent it is by cutting a hole in one of the glass windows and and using the special fitting. I wanted to ...
24
votes
1answer
33k views

Humidity Levels

What is a healthy and safe humidity level that I should try to keep my house at?
19
votes
3answers
23k 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 ...
8
votes
3answers
102k 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 ...
26
votes
2answers
3k views

What is an air conditioner compressor hard start kit and how does it work?

My air conditioner compressor wasn't functioning properly recently. The compressor wouldn't start when the start relay energized. A HVAC technician diagnosed the problem nebulously as "It needs a hard ...
12
votes
6answers
46k views

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

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 ...
7
votes
3answers
3k 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 townhome/...
6
votes
7answers
154k 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 ...
6
votes
7answers
5k 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) ...
5
votes
2answers
4k 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
11k 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 ...
4
votes
5answers
58k views

Why would my Goodman gas furnace start but not stay on for more than 2-3 minutes?

I've got a problem with my 15 year old Goodman furnace. It starts w/o problem, inductor begins working, hot surface ignitor lights up and ignites the gas. Then the main blower starts working and the ...
4
votes
1answer
92k views

On a thermostat, are “R” and “Rh” terminals the same thing?

I have an older thermostat controlling an old ass Trane furnace with A/C. It has an "R" terminal and an "Rc" terminal (they are jumpered - see photo). I see references to an "Rh" terminal online. Are ...
3
votes
3answers
24k views

Why is my furnace blowing cold air?

My HEIL 7000 natural gas furnace has stopped working what are the most likely causes, and how to verify faulty parts? Normal operation routine Thermostat sends "need heat" signal. Exhaust blower ...
3
votes
1answer
332 views

How to use the 2015 IRC Chapter 24, G2407.6.2 to determine combustion air?

The 2015 International Residential Code (IRC), Chapter 24 ("Fuel Gas"), Section G2407.6.2 allows for one permanent opening to be used to supply outdoor combustion air into a mechanical room for gas ...
3
votes
2answers
225 views

Even heating in home with partial basement

How can I evenly heat a house with a partial basement, as shown in the diagram below? The rooms over the slab are consistently several degrees cooler than the rooms over the basement, particularly ...
2
votes
1answer
1k views

Condensation on HVAC Ducts in Basement

In general the AC in our house works reasonably well (though I haven't done performance tests on it yet). It's a single stage 3.5 ton heat pump/AC original to the house, which was built in 2002. ...
2
votes
0answers
56 views

How do I stop the ticking noise coming from my furnace duct? [duplicate]

I've had some HVAC people here to look at the ticking noise coming from our furnace duct. One of them installed a brace on the piece in question. This seemed to make the ticking less frequent, ...
1
vote
1answer
79 views

Air handler blower, motor, or something else?

My blower just stopped working. I have 240 volts to the motor but it won't spin. It will turn an inch or so but that's it and it tries repeatedly. Could it be something besides the blower or the motor?...
0
votes
2answers
2k views

Indoor blower fan turns on and off intermittently in 10-15 min increments when system is off

Bit of background: The furnace blower originally did not not turn off at all (or if it did, very rarely did so), even when set temps were reached or when the system was off (fan setting is set to auto,...
0
votes
1answer
2k views

How can I use a second transformer to power my zone controller?

My system uses an EWC Controls model NCM 300 zone controller, that is currently powered using the transformer in the air handler unit. I'm installing two new smart thermostats, and the power ...
21
votes
7answers
24k 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 ...
6
votes
5answers
31k views

Can a homeowner without a Section 608 EPA license legally connect his own gauges to his own air conditioner if the unit uses 410a refrigerant?

It has been suggested by at least one moderator on this site that EPA Section 608, which restricts who can purchase and handle refrigerant, including who can connect a set of manifold gauges to a unit,...
6
votes
3answers
18k 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 ...