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

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33 views

Why is ERV (return-return) installation not recommened?

I just had an ERV installed I was expecting the install to be return-return (ie indoor air from return duct pushed outside, and outside air pushed back into return further down the return). The ...
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3answers
66 views

Ac unit set on 74

My central air is set at 74. Yesterday and today, the house was up to 80. It has been very hot outside(90). Would this affect my ac unit?
2
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2answers
32 views

Can I use a secondary thermostat as a timer for my air conditioning system?

I want to install a timer on a split air conditioning unit to accommodate my energy plan hours. Too many people change the thermostat. Could another thermostat be used at the pump, controlling one ...
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2answers
62 views

Blower motor lost RPMs after reversal of fan direction

My air handler requires a clock wise rotation of the fan motor. After installing a new motor I found it was set in the counter clockwise position. I changed the wires (switched inline connection on ...
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0answers
50 views

noisy Air-conditioner compressor

I bought a new split AC that worked great for a week or so, but now I can hear some annoying noise coming from the outdoor unit. The outdoor unit in installed on a flat roof so I can hear this noise ...
3
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4answers
26k views

How much less power does a three-phase A\C unit use as apposed to a 220v unit?

I'm planning to install a 5 ton central AC. I'm deciding between a condensing unit that runs on 220V and a costlier unit that runs on 207Y three-phase. My understanding is that three-phase motors use ...
2
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3answers
10k 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 ...
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0answers
22 views

How to connect honeywell wifi thermostat to trane A/C unit

My current system has 4 wires to the thermostat. I need to add the C wire for the new honeywell wifi thermostat. On the wiring board of the a/c I found 26vac on one terminal. The red wire to the ...
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7answers
43k 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 ...
4
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1answer
122 views

Is it possible to install a whole house humidifier away from the furnace?

My building is essentially a single extremely large room. It's a 25'W x 45'L x 20' H concrete box, with an open mezzanine over the back 1/3 of the box. The HVAC system is gas-fired forced air, ...
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2answers
91 views

How can I wire my WIFI thermostat to control my millivolt fireplace?

I have a gas fireplace that has an millivolt on/off switch on my wall (and a remote that includes flame on/off, a countdown timer and a thermostatic flame control). I want to be able to program ...
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0answers
31 views

Moved thermostat now ac wont turn on

So i was moving my thermostat to another room. I cut the wire to splice a new wire in. I got zapped first then spliced the wire. Now my thermostat is good to go but when it calls for the ac to kick on ...
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4answers
11k views

Can I using a 3-phase connection to power 1-phase AC unit?

I have preparation for an AC connection with 3-phase 220V 3X16A breaker. I want to install a 220V 1-phase unit, which also needs a 16A breaker. The physical connection has screw-on terminals, so there ...
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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
77 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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1answer
56 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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2answers
63 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
60 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
104 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 ...
2
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1answer
113 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 ...
2
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6answers
29k 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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3answers
53k 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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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?
3
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2answers
117 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
192 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
120 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
votes
1answer
420 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 ...
1
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1answer
65 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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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 ...
0
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3answers
116 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 ...
1
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0answers
27 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
63 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
111 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
99 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 ...
1
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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
154 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
57 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 ...
1
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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 ...
8
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1answer
9k 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
187 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 ...
2
votes
3answers
11k 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
22k 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
92 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 ...
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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 ...
3
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4answers
11k 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 ...
3
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2answers
2k views

Can I attach a HEPA filter to the HVAC outlet?

I am currently living in China and want to improve the indoor air-quality. We have a Hitachi R410A HVAC. All the room in the house are controlled separately. Just to make it clear up front, I am not a ...
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2answers
268 views

WIFI thermostat no C wire

I hooked up a Honeywell WiFi thermostat last fall. There is no C wire in the furnace & the Honeywell rep suggested I wire up a small separate transformer with new wires going to the C and RC ...
2
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1answer
6k 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 ...
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0answers
25 views

Residential HVAC: one main thermostat, what do the other thermostats in the rooms do?

Are the other thermostats only meant for non-force air heat only? Does it mean only one thermostat in the house needs to have both heating and cooling, and auto or fan-only switches? It sure make ...
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0answers
89 views

replacing single pole York A/C contactor

I am trying to replace a single pole contactor with burned contacts on York package unit Model D3YS030N064069. The old contactor has four 24 volt lugs on one side. The new contactor has 2 on each ...