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

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0answers
19 views

connecting into 24v on HVAC transformer [duplicate]

I've located available 24v to tap into on my transformer but what's the physical procedure to add my tstat wire for C?
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0answers
70 views

Will a DIY Air Conditioner help my HVAC Central Air system?

So the husband and I just moved to Texas. We went away for the weekend and turned our HVAC central air from 68F and ON to 75F and AUTO. For some reason when we got home the AC wouldn't drop. Now I ...
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2answers
181 views

Gap between 6“ dia wall thimble & 6” hvac pipe

I bought a 6" dia aluminum wall thimble to vent my 6" dia hvac steel exhaust pipe through to the outside. However, the diameter of the 6" thimble is actually 6 3/4". How do I effectively insulate the ...
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1answer
58 views

Where does the C wire connect in a dual transformer system?

When wiring a common ground (C wire) for a dual transformer system, does it matter which transformer you connect the ground too? I'd assume that the ground on either transformer would serve as a ...
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1answer
65 views

Issues after capacitor replaced on AC unite

Had a checkup on my AC/ furnace a couple weeks ago. The technician said the capacitor leaking oil and not pulling enough amps. He recommended me getting a whole new system. (my house built 6 yrs ago) ...
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1answer
31 views

How can I better control temperature differences between floors in my two story home that has two HVAC systems?

We have 2600 sq ft on the main level and 800 on the 2nd floor. To the 2nd floor, there is a staircase and with a door on the bottom floor. We have our master upstairs and don't use the room at all ...
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1answer
50 views

How can I increase the effectiveness of the A/C in a hot 2nd floor converted attic master suite?

Just bought a 1940's masonry construction house. House has a finished basement (cold as a meat locker), first floor (comfortable) and 2nd floor (too hot). The 2nd floor is an attic that has been ...
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1answer
89 views

lennox AC condenser Fan running backwards

I have been trying to figure this out for a little while and about to check into the nutty house!! The Condenser fan went bad in my AC Unit. It was a 3 wire motor. I got a Universal replacment motor ...
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2answers
57 views

How can I add a C wire with this unusual installation?

I recently got a new Honeywell WiFi thermostat, which requires a C-wire. I have 5-wires going to my current thermostat, with only 4 being used. So I thought adding the 5th as my C-wire was going to ...
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2answers
43 views

Why “W” (heat contactor) and “E” Aux Heat connected in Thermostat

I'm trying to update my thermostat to one that has a scheduling feature. My plan is to just copy how it was hooked up in an old 129N Thermostat from Armstrong however, I can't figure out why the "W" ...
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1answer
82 views

Central AC Tripping Circuit Breaker (sometimes)

When my AC first turns on, it will typically trip the circuit breaker shortly after the compressor and fan start up. If I reset the breaker, and turn the AC back on, it will usually run just fine and ...
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1answer
74 views

What is the best place to install an Air-conditioner in a room?

I'm trying to decide where to install my ductless split Air-Conditioner. For the indoor unit, is it ok to install it above a window? will placing the indoor unit at the corner of the wall reduce the ...
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6answers
24k 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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1answer
48 views

What is causing this air-conditioning unit to cool on cold days?

This is a temperature log from a reverse cycle air conditioning system that has run fine for getting on for 30 years. It has suddenly started to blast out cold air on days when it should be heating. ...
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3answers
48k views

Why won't my A/C turn on after I replaced the thermostat batteries?

Our thermostat died yesterday, but after replacing the dead batteries with fresh batteries, and confirming the LCD screen was operable, our AC no longer turns on. I have attempted a factory reset on ...
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1answer
124 views

heat pump/air conditioning wiring to thermostat

We decided to change the thermostat of our heat pump/air conditionnning unit. First 3 images are the old unit. The first 3 wires(1 and 2 picture) yellow red orange were not connected to anything, just ...
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4answers
3k 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 ...
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1answer
233 views

Will splitting a duct to extend HVAC to an addition cause problems?

I'm building a 15 x 26 addition off of current family room to use as a music room. The family room has 2 vents(registers) where the family room meets the new room, and because of convenience they ...
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4answers
150 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?
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2answers
89 views

Why “extra” power disconnect for small HVAC unit?

I am in the throes of learning enough to do a DIY install of a small heat pump package unit. The installation manual calls for (and suggests that NEC requires) a "fused disconnect" inline with the ...
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1answer
248 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
320 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
179 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 ...
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2answers
110 views

Is it economically reasonable to cool the roof by water evaporation

I want to estimate the outcome before going into hassle of installing the sprinklers/mist emitters. I have a place on the last floor, you can call it an attic, directly under a flat roof which is ...
2
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1answer
398 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 ...
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1answer
49 views

Why would my zone controller be displaying error: AC voltage insufficient?

Our AC unit was new with our house and is only 7 years old. We have a split zone system controlled by a Honeywell HZ322. Today we had no AC so I started looking at possible issues. When I got to the ...
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1answer
108 views

Why would only 1/3 of my registers be blowing warm air?

I have a Coleman gas furnace in a wall space in my house which somehow shares the blower on my a/c unit on the roof because it turns on when furnace is called to start, though it does bump up after a ...
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0answers
26 views

Thermostat and thermostat system for small business with several units and tenants

Am the facilities guy in a small church and pre-school. There are 8 heat pump units through out the church/schoool. Each has a stand-alone thermostat and they are all different. I would like to get ...
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1answer
21 views

Just installed central 4 ton fau condenser and evaporator but don't know how to install thermostat from condenser to fau to the thermostat

I installed a furnace evaporator and condenser brand goodman 4 ton unit but need to know how to connect thermostat from condenser to the furnace to the thermostat if any suggestion.
2
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4answers
14k views

How do I wire an old furnace motor so I can use it as a garage exhaust fan?

Since last I posted, I moved WAY south (lil warm down here) and the house I moved into was a foreclosure so a few things needed done, namely the AC and furnace. When the guy did the job he said he ...
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1answer
720 views

Where is my common wire on the unit?

I have 2 systems in my house, my heat is gas hot water radiator heating and A/C is a separate newer system. I'm trying to figure out if I can run a C wire off air handler from the A/C system to run ...
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2answers
190 views

G to C trick not working for cooling. Honeywell RTH9080WF

My electric furnace has no c terminal. Furnace is heat & cool both. (Lennox Electric Fan coil Model CBS18-21-3P). I installed Honeywell RTH9080WF. I switched G to C on my thermostat and got the ...
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1answer
81 views

Is there a wireless way to cut off the HVAC y wire from my generator transfer switch?

I recently had a Generac Synergy generator installed, which went smoothly, however there was no good way to get the Y wire from my thermostat to the transfer switch and back in order to allow the ...
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1answer
40 views

Window AC not cooling

I've GE window AC 0.75 ton it has stopped cooling I cleaned the nylon net properly with old tooth brush,it was totally blocked Then I combed the metallic horizontal fin like structures which were ...
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3answers
106 views

Do I need a neutral wire when connecting a 240V device?

So this is still not very clear to me: I am trying to get 240V to an appliance that does not need a plug (direct wiring), I won't need a neutral wire, is this right? In fact there is nowhere to ...
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0answers
20 views

Should I install a doorway fan or dehumidifier?

I have central air in a rancher (one floor), and the living room is on one end of the house. That room is on a slab, and has always been noticeably hotter in the summer and colder in the winter than ...
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0answers
47 views

how to install a casement window ac unit in a standard horizontal window?

Ok... I have scoured the internet. I was given 2 casement window ac units. Both of my heat pumps were stolen and this is an army wife turned widow make do type situation for while I save to replace ...
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1answer
104 views

What if my Trane 3 ton 13 seer heat pump is unable to generate enough heat to reach the set point on the thermostat?

The unit turns on when thermostat temperature is set higher than room temp. It blows cool air for several minutes and then the emergency heat kicks on and warmer air comes from vent. This lasts for ...
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1answer
73 views

Is installing a packaged HVAC unit (PTAC) a realistic DIY project?

I'm a handy guy and can do pretty much anything around the house that I put my mind to. Assuming I can handle the part of the install that is outside (the concrete pad, the hole in the crawlspace ...
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0answers
18 views

Single Stage or 2 stage furnace

Just bought a house that has a furnace on last legs. House is 1941 masonry (Chicago). 3 floors: finished basement, first floor, 2nd floor (converted attic with vaulted ceilings and way too hot). Total ...
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1answer
72 views

ecobee3 Installation - Thermostat Y Terminal (yellow) Wire Connects to C Terminal Board

enter image description hereI'm attempting to install a new ecobee3 on an older Coleman Evcon gas furnace and AC HVAC system. The system is what I would consider typical residential as far as I can ...
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0answers
37 views

My A/C Unit stopped working after replacing blower motor

Any idea what I may have done wrong here or how to check? I replaced my blower motor (it was 100% compatible and had the proper capactitor), and upon starting it up the blower did nothing and the ...
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2answers
17k views

Why won't my heater turn off when it reaches my desired temperature?

My wife and I purchased our first home this past year and we did a bunch of repairs up-front via a rehab loan, and one of the things we replaced was a very old thermostat with a new digital one. I ...
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1answer
8k 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 wires do I need to connect to turn on the A/C? Is there a risk of damaging any ...
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2answers
167 views

Why does my HVAC begin vibrating and stop cooling at night?

I am calling a HVAC technician since this is probably too complex a problem for me, but wanted to hear some possible diagnosis. The symptoms are as follows: The A/C is working well during the day ...
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3answers
10k 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. ...
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2answers
17k 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?
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2answers
61 views

Why does my furnace run periodically when the thermostat is off?

I just moved into a small apartment that has oil tank / water baseboard heaters. At first the furnace would not come on at all, after hearing the "click" in the thermostat. Maintenence was sent 3 ...
2
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1answer
329 views

AC unit won't turn on: both inside blower fan and outside fan unit won't turn on

AC unit won't turn on: both inside blower fan and outside fan unit won't turn on. It is as if I had gone to the circuit breaker and cut the power to the whole HVAC system, but I didn't. I've been ...
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2answers
7k 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 ...