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

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0
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3answers
34 views

Why does the outside fan stop but the blower fan continues to run?

We can have the thermostat set on 76 but wont stay 76 in house. Will come on when temperature is 79 in the house.
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1answer
119 views

Can I connect two wires to a single screw terminal in my HVAC system?

I am installing a new honeywell WiFi thermostat but the old battery operated thermostat had batteries and no "C" wire. I look at both the thermostat and the air handler and found an extra un-used blue ...
0
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0answers
5 views

No “C” terminal on Trane air handler [duplicate]

I am installing a new honeywell WiFi thermostat but the old battery operated thermostat had batteries and no "C" wire. I look at both the thermostat and the air handler and found an extra un-used blue ...
1
vote
2answers
38k 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 ...
1
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0answers
29 views

Can I remove HVAC pipes after exposing the ceiling?

I recently removed the drywall ceiling from my basement and have two related questions about removing the HVAC ducts/pipes. Pictures attached here: http://imgur.com/a/qep4w 1. Is it OK to remove the ...
2
votes
2answers
1k views

What can cause an A/C to freeze up

Our A/C evaporator coil freeze up last year, so I called out a technician. He said that it was charged with the proper amount of Freon, and my problem [paraphrased] "something had narrowed the inside ...
3
votes
4answers
9k 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 ...
0
votes
1answer
146 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 ...
1
vote
1answer
219 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 ...
1
vote
1answer
256 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 ...
0
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0answers
53 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 ...
2
votes
1answer
301 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
vote
1answer
92 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 ...
1
vote
2answers
77 views

HVAC contactor sparks when AC kicks?

The HVAC and control board is a McQuay Mark IV. I'm not sure if I would like to try and fix this myself yet. Just trying to figure out the issue before deciding where to go. Here's the scenario: ...
0
votes
0answers
48 views

Why would my AC turn on and off randomly?

My AC unit turns on and off randomly regardless of whether the thermostat is set on or off. I've even tried removing the batteries. Does anyone know why this might happen?
0
votes
1answer
597 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 ...
0
votes
1answer
41 views

Allergies and an economizer

I had an economizer added to my HVAC system last fall, which is fantastic for cooling my second floor down in the evenings during the shoulder seasons where the weather is cool in the late afternoon ...
1
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0answers
52 views

How can I use a portable A/C unit to cool my clean room?

So, I have built a room inside my shop, a clean room for finish and airbrushing. I want to cool this room as I spend more time in it than the rest of my shop (garage) So, I get a portable unit. ...
3
votes
1answer
61 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 ...
1
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0answers
21 views

How to Change Chinese HVAC Thermostat

I am looking to put Nest thermostats in the house, I have now found out my entire house (one in each room, 6 of them) has been wired with HVAC Chinese U12A UNIVERSAL A/C CONTROL SYSTEM urrgh – they ...
2
votes
2answers
118 views

Should I convert from a rooftop to a split HVAC system?

We have a packaged HVAC on the roof and the AC needs to be replaced. It's 23 years old and dying/dead. We were considering buying just an AC and keeping the package unit running for heat. We feel ...
1
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2answers
38 views

Is having a branch off the end of main heating HVAC duct bad and if so, why?

Question: Is having a branch off the end of main heating HVAC duct bad and if so, why? Background: A heating and cooling contractor sales representative came to my home today. He saw the situation ...
0
votes
2answers
74 views

What could cause the blower in my furnace to come on?

Ok my blower just turned on, my propane furnace and it's not in operation due it being summer. My thermostat is set at 65 and the room temp is 78. The heater never actually fired it was only the ...
0
votes
2answers
66 views

Why do I have to start my furnace manually every morning?

The oil furnace works fine all day and evening, then overnight I have the programmable thermostat lower the temperature at 11pm. But every morning at 5am when the thermostat tries to turn the ...
1
vote
1answer
27 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 ...
1
vote
1answer
790 views

Why is my furnace blower running at low speed?

My Payne gas furnace (PG8UAA 42091) automatically shuts down after it lights and burns for two minutes. It then gives a 33 fault code. I've done some research and some testing and have narrowed the ...
0
votes
4answers
3k views

How can I modify a 4 wire thermostat to a new thermostat requiring c wire?

I attempted to replace my thermostat with a fancy new Trane z-wave enabled model. To my dismay my home was only wired with a 4 wire setup with no 5 hidden in the bundle. I followed Insx on the web ...
1
vote
3answers
71 views

How to hide AC lines up against brick siding

I had this AC system installed, and didn't realize when asked about what location i'd prefer the compressor that it would look so ugly having it off the corner of the building instead of in the middle ...
1
vote
1answer
63 views

HVAC replacement

we just recently purchased an older home- 1978 - 2200 sqft, 2 stories, 2 14x20 returns - one downstairs, one upstairs, 5 ton 10 seer system, 10yr old goodman air handler but the condensor is unkown ...
14
votes
10answers
17k 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 ...
1
vote
2answers
255 views

Furnace blower motor won't turn off

I've replaced both limit switches on my Comfortmaker furnace plus the control board. Blower continues to run and the unit will still heat my home. Component changeouts did not make a difference in ...
3
votes
2answers
3k views

$400 electric bill traced to heater - what could be wrong with it?

Back in December/January, we got a real shocker; a $400+ electric bill. I thought there must be a billing error, so I went out to the meter, and found that not only was the number probably right, we'd ...
1
vote
1answer
47 views

Appropriate register for duct size?

So I asked a long-winded version of this question in another thread, but haven't really received any good responses yet. I'm going to condense and try again... There is an 8" duct feeding a 6x12 ...
6
votes
3answers
1k 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 ...
3
votes
1answer
35 views

Can I replace my draft inducer blower with a model of a slightly different speed?

My furnaces draft inducer blower sounds like a snow blower running, so I set out to replace it. Finding a replacement part proved difficult, but I found a site advertising a compatible part and ...
2
votes
4answers
2k views

How “freely” should a central A/C condenser fan spin

Last year my home's central air condenser fan motor stopped working. When I noticed the house wasn't cooling down I went outside to investigate and found there was a humming sound coming from the ...
1
vote
1answer
101 views

Did I wire this thermostat properly?

Just want to make sure I have this correct: Have M1MB 070a BW heat/ac unit w/ a 710152B control board and a Coleman outside condensing unit. -Have a four wire thermostat. R,Y,G,W -Have 2 wires coming ...
0
votes
0answers
68 views

Would increasing the size of the A/C duct for my kitchen improve cooling?

As part of an ongoing kitchen project, I'd like to relocate the existing a/c register in the ceiling (which is located next to an interior wall) to the center of the room and upsize the duct (and ...
0
votes
2answers
7k 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?
1
vote
2answers
119 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
1answer
50 views

Why would my boiler expel steam when it's set at 180F

So, I have recently had some issues with my boiler (hot water - not steam) system. After hiring some guys to stop by and take a look at it, they told me that the boiler pressure reducing valve, ...
2
votes
2answers
65 views

Are there optimal positions for A/C and heat register grills to be facing?

I noticed a while ago that some of my A/C and heat register grills are facing the walls and not the room (the insides of the curves on the grills face the walls) in some rooms but not in others. My ...
3
votes
2answers
618 views

What could cause a flame sensor to stop working so frequently?

Over a year ago after a month in our new house, we came back one evening to a cold home and after some googling, I found out that the flame sensor was dirty and the furnace was starting the flame and ...
1
vote
1answer
50 views

Why is it taking so long for my A/C to start?

When I turn my AC thermostat to cool, I can hear it click but the outside unit does not start and no air blows inside. Several hours later everything turns on and it works fine. If it turns off, ...
1
vote
2answers
5k 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
63 views

Is my HVAC system unbalanced?

I bought a home back in August and the previous owner had a new 3-ton HVAC system installed. Basically right now the HVAC is located in the upstairs hallway, and the way the duct is set up is there ...
1
vote
1answer
235 views

Adding a C/Common wire to HVAC system

So I'm looking for some help in identifying where I can attach a C/Common Wire to my HVAC system, but unfortunately my system doesn't have a control board that I can easily attach a powerkit to. For ...
2
votes
1answer
5k views

Does a compressor with a short to ground really require a complete system replacement?

My 24 year old home A\C went out some time Sunday morning. I had a tech come out and look at it, and was told that the compressor is shorted to ground, and that this means I have to replace the entire ...
3
votes
5answers
204 views

How can I vent a portable air conditioner when there's no window?

My shop does not have central air and does not have operable windows. There is a steel door in the back and cinderblock walls. My landlord is against me cutting a venting hole in either the steel ...
3
votes
3answers
341 views

What material is allowed for a furnace room ceiling material?

What types of material, other than drywall, are acceptable by Ohio HVAC Code for the ceiling of a small furnace room which will: Have return air ducts (only) passing through it to attic space. Butt ...