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

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0
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1answer
181 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
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1answer
160 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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0answers
35 views

Testing the exhaust of a natural gas furnace?

I recently had maintenance performed on my natural gas forced-air furnace. During this maintenance, the technician went outside and used an electronic handheld device with a wire-attached probe to ...
2
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1answer
156 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
56 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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1answer
36 views

Could an unlevel furnace be causing noise from the blower fan?

The blower fan on my gas furnace sounds like it is hitting other metal when it turns on or off. I had it serviced and he replaced the blower run cap but it has started again after about a week. ...
3
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2answers
115 views

Should I patch this hole in my slab?

I'm in the process of tearing out carpet and installing laminate in my guest bedroom. After I got the carpet out, I discovered a hole several inches across underneath the wall that borders the garage. ...
0
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1answer
392 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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4answers
5k views

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

I Purchased the Honeywell WiFi Prog Thermostat to replace my Round Digital Honeywell Thermostat. I have separate Heating and Cooling (Heating is a Weil McLain Boiler for Hot water baseboard and Hot ...
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0answers
27 views

What size exhaust fan do I need for a pool house?

What size exhaust fan ( how many CFM ) do I need for my pool house . The pool is 36 feet x 18 feet x 8 ft deep, and is kept at 32 C. The building is 42 x 28 feet, 10 feet high ceiling, all insulated, ...
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0answers
21 views

How do I measure the size of a duct that runs through a finished wall (the register end is accessible)?

I am trying to redo a Manual D for my house (heating mainly). I can pretty much determine the length of each run but I can't figure out the exact size of the ducts that are already installed The ...
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3answers
16k views

How can I prevent my HVAC condensate drain line from freezing?

Last night, my heat (forced air) suddenly stopped. Today, a plumber figured out that my heater is 90% efficient, produces lots of condensate, and the drain line had frozen. We went outside and saw ...
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1answer
200 views

What does the low limit do, and where should it be set on an oil fired hot water furnace?

What does the low limit do, and where should it be set? My furnace has a honeywell triple aquastat relay and has a difference dial. Water temp is about 190 deg F. Also, water psi gauge is only ...
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5answers
88k 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 ...
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1answer
2k views

How to diagnose a broken Aprilaire humidifier (Model 600)?

I have an Aprilaire Humidifier Model 600 (or maybe 600M) mounted on my furnace. The humidifier is not turning on (i.e. letting water flow over the filter) when the furnace is on. The below images ...
3
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2answers
131 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 ...
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0answers
26 views

What could be the reason why all my registers at foundation slab level have weak air flow?

In the picture below all the ducts that have a long leg going toward foundation have weak air flow. Read the details on the picture Could anybody tell me what is the problem with these guys? The ...
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2answers
60 views

How do I calculate CFM for a structure?

This is for calculating the CFM (cubic feet per minute) of air that the blower needs to move in order to compensate the total heat loss (ventilation,infiltration,heat loss through walls, windows, ...
2
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1answer
39 views

How can i add a common “C” Wire to this old system?

I have an oil HVAC that was put in back in 1996. I sadly do not know the model of the furnace and cannot dig out any paperwork on it. Anyways, i want to go with some of the bells and whistles for a ...
3
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2answers
17k views

How can I prevent my house from smelling of smoke after having a fire in my fireplace?

We have a wood-burning fireplace in our family room. Fifteen feet from the fireplace is a large cold air return. When the fireplace is stoked, nice and cozy, everything is fantastic. When I shut it ...
2
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1answer
257 views

Can I connect an additional wire to HVAC system where all the terminals are full?

I'm installing a new thermostat (ecobee Smart Si) and it requires "C" wire. I checked before I bought, and saw an unused blue wire behind my current thermostat. However after connecting everything the ...
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0answers
24 views

How can I adjust a whole-house ventilation bathroom exhaust timer?

We have a home built in 2008 in west-central Minnesota. As a cost-saving (I perceive it as such, and may be mistaken) measure to fulfill air quality and venting code, the builder set up an upstairs ...
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3answers
7k 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
1k 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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0answers
46 views

Can ultrasonic humidifiers be used in a bypass setup for a whole house humidifier?

My home is about 3000sqft, with lots of high ceilings. I'm having trouble keeping the relative humidity up in the winter. When it gets down to 10F outside, the RH drops down as low as 25%. This is ...
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1answer
53 views

Adding an on/off switch for my furnace fan

Here is my situation, I want to be able to run the blower on my furnace during the summer so that the cool basement air can be circulated thought the house. I live in an old house and the thermostat ...
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0answers
37 views

Whole house humidifier - can you use a steam/mist with a heat pump?

Just moved into my new house and first time with an electric furnace and forced air with a heat pump (rheem) - and immediately we noticed that our skin is super dry and cracking. I was looking into ...
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0answers
33 views

HVAC ducts ready for finished basement?

I'm starting to finish my basement. Before I do so, I want to be sure the ductwork is sufficient to keep it warm during Colorado winters. The basement was finished when we moved in, but gross, so we ...
8
votes
1answer
36k 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, ...
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0answers
52 views

What is the smell coming through my HVAC system?

If I leave the furnace fan always running for an extended period of time (to circulate and filter the air), when the central AC turns on there is a not-so-fresh smell that is emitted through the ...
3
votes
1answer
4k 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 ...
0
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1answer
50 views

What could be causing my gas fireplace to shut off?

I have a gas fireplace that is 4 years old, that shuts off after a couple of minutes. The pilot lights ok, then the burners turn on and work fine for about 3 minutes. After that the entire fireplace ...
4
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2answers
12k 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 ...
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2answers
120 views

Can we capture the hot, humid air from a gas-powered clothes dryer during winter?

During winter we run a gas-powered heater and evaporative humidifier to maintain indoor air quality. Meanwhile, every day (big family!) we run a gas-powered clothes dryer which dumps hot, humid air ...
0
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1answer
53 views

Gable venting a bathroom fan and kitchen range hood

I am planning on venting my bathroom fan and the range hood in my kitchen out the gable end of my house in separate runs. The gable end is above a gable roof, so I am hoping for some recommendations ...
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2answers
88 views

Can I move second-floor duct-work from the floor to the attic

I have a two story home that sits on a slab. There is some duct work that runs through the slab. I have some duct work that runs through the ceilings of the first-floor and points towards the floor of ...
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2answers
396 views

Is a PTHP an HVAC option for a super or well insulated structure?

Is a Packaged Terminal Heat Pump a good HVAC system for a structure that is super insulated or passively insulated assuming the unit is sized and fitted to meet the needs of the structure. There is ...
1
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1answer
133 views

Zoned oil furnace and AC thermostat question

I recently moved into a new home and wanted to replace the old thermostats with digital Honeywell ones. From what I understand the home has a Rheem 10 Seer (1996) compressor and a Williams oil furnace ...
1
vote
1answer
21 views

will using a ventilation system with an heat exchanger give me the same quality air indoors as outdoors?

will using a ventilation system with an heat exchanger give me the same quality air indoors as outdoors? is using a proper ventilation system equivalent to having all your windows open without any ...
0
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1answer
272 views

I just had a heat pump installed. I had central air already so the duct work was there already for a/c. Should my vents in the ceiling be changed?

One person told me I need to change my Registers on the first floor that are in the ceiling because the house was set up for air not heat. They say the Registers I have keep the cold air going a ...
0
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1answer
225 views

Air Conditioner woes: water pooling in basement, condensation on ducts, frost on outdoor copper pipe

Can someone help diagnose what's wrong with my air conditioner? The symptoms are: the air that it is blowing is not very cold It's colder than the ambient air, but not cold enough to cool the ...
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0answers
56 views

Can changing the fan speed on a forced air heating system reduce the sound heard in each room?

We recently converted to gas heat. Now, when the heat turns on, there is very loud blowing in almost every room. My Carrier Infinity fan speed is set to "Auto." I was told there is nothing to do ...
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0answers
30 views

Why did my central heat shut down?

I did maintenance and turned on the electric heater switch on thermostat to Central Unit. It came on just fine and warmed up the house and shut off automatically. But it never came on again. The a/c ...
3
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3answers
17k 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 ...
0
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0answers
16 views

Should my Trane dual zone XB14 be short cycling?

I have a 2 yr old Trane zone dual system and it is short cycling whenever I run the ac side, I called the HVAC installer and he said that is noraml due to the fact that the temperatur is 72 degrees ...
1
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1answer
156 views

Can I install a humidifier on a horizontal duct?

I have a Honeywell whole-house humidifier (HE360A1075). Can this be installed on the horizontal ducting here on the left? It feels like it's an aluminum box under the tape. This is both gas heat and ...
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3answers
90k 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 ...
6
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3answers
756 views

Why is my power flickering across multiple circuits?

I woke up this morning and went downstairs to find that none of the lights would come on (lights were working fine upstairs). My first instinct was thinking that a breaker had tripped, so I went to ...
2
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5answers
10k 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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0answers
24 views

Why is my hydro kinetics system blowing out cold air?

I have a hydro kinetics system that is blowing out cool air when set to heat. Thermostat was replaced when I bought the house a year ago so I don't think that's the issue. Toggle switch is set to ...