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

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1answer
30 views

How can I move hot air from a cathedral ceiling to colder bedrooms?

My main living room has a 25 foot cathedral ceiling with a ceiling fan including a staircase going to the second story bedrooms. The thermostat is situated in this space. There is space to install a ...
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1answer
24 views

Adding a “C” wire for a wireless theromstat

I have a heat only system with two wires leading to the thermostat - red and white - and am wanting to add a wireless thermostat. The new thermostat however requires a "C" wire. Can I add a C wire?
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2answers
90 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 ...
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1answer
26 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
535 views

Installing Honeywell WiFi Thermostat

I am trying to upgrade to a programmable thermostat. I bought the Honeywell RTH9580 with WiFi. I can get power to the new thermostat and get the fan running. However, it will not work when the fan ...
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2answers
26 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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1answer
338 views

No electricity going to thermostat

Our old thermostat is working but I want to change to a new one (nest thermostat). I have two exact HVAC unit at home. I change one it works but when I change the second one it doesn't work because ...
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2answers
348 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 ...
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3answers
6k 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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3answers
351 views

Does my crawl space need venting

I have a crawl space under my main entrance of the house. It's about 3' tall. I added a heat duct because the floor at the entrance was always cold. So my question is do I need to vent the crawl space ...
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1answer
382 views

How can I add a C-wire to a Venstar T5800 thermostat?

I am trying to replace my existing thermostat. My old thermostat has: Rh, W (coming from the heating unit). Rc, Y, G (coming from the AC unit). On the Venstar T5800, I can map as follows: Rh+Rc ...
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2answers
263 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 ...
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1answer
314 views

why does my heat pump wiring diagram show 7 wires going to the thermostat but the thermostat only says it needs 5?

Here is a link to the wiring diagram for my heat pump. The thermostat that I am planning on buying has the following terminals C, G, Y, O/B, RC, R, Aux, E, and L. The instructions say to jump the RC ...
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1answer
99 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 ...
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1answer
114 views

How do I connect a C wire to an Utica PEG112CDE steam boiler?

I want to upgrade my old mercury thermostat that I currently have to a newer programmable thermostat. This little DIY project is for my first late 1920's home that I recently purchased. I currently ...
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1answer
41 views

How can I determine what grade air filter is appropriate?

I'm trying to figure out what kind of air filter is appropriate for my house. My local home warehouse store stocks over a dozen options. The primary difference between them seems to be Microparticle ...
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1answer
29 views

What could be causing my Lennox furnace to blow cool air?

My Lennox outside furnace is blowing cool air, not hot even when the burner is lit. It takes 3 times longer to heat the house than it should. I just had the draft motor replace about a month ago and ...
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1answer
13 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 ...
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1answer
74 views

Can I cap the air return in my unfinished basement?

I noticed today that there is a massive air return in my unfinished basement. The opening is about 2 meters from the blower, and as large in diameter as the return duct coming from the upstairs. This ...
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2answers
83 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
224 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 ...
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0answers
53 views

Does anyone have experience with small heat-recovery air exchangers?

I know there are units made which are supposed to be sized for use in a residential kitchen, as a more efficient replacement for the usual vent hood (bring air in to replace air blown out, but ...
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3answers
4k views

What kind of wall switch is needed for a natural gas fireplace to ignite consistently?

When we moved in, our natural gas fireplace worked well: Flick the switch & it would ignite. Years later, it started acting erratically: Sometimes, the switch worked, other times, no luck. We'd ...
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1answer
189 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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3answers
11k 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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0answers
26 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
19 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 ...
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0answers
26 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 ...
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3answers
16k 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 ...
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1answer
23 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 ...
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0answers
7 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 ...
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1answer
152 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
46 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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1answer
117 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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3answers
87k 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 ...
2
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1answer
79 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
20 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. ...
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2answers
181 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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3answers
668 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 ...
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2answers
298 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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1answer
165 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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1answer
49 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 ...
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1answer
129 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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5answers
9k 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
15 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 ...
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2answers
119 views

At what temperature should an unoccupied house be kept at in winter?

We are moving to a new house and unfortunately we don't have our house sold yet. I was wanting a recommendation as to what temperature to keep the furnace going @. I found a good recommendation to ...
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2answers
96 views

What are the possible reasons I am not getting cold air from my air conditioner?

my heat pump outside is working but my central air conditioning/heating unit in the garage makes a hissing sound or faint sound of water running. There is air coming from the vents. The very last time ...
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0answers
34 views

What could cause the heat side of our split pack heating/air unit to stop working?

Our heat side of our split pack unit (runs on propane) come on and will runs little bit but then won't come on again. We can turn it off for a while and then it will run again. What could be the ...
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1answer
230 views

Can I have a separate thermostat for a wood boiler?

I want to wire a separate thermostat for my outdoor wood boiler so that just the furnace fan will come on without the propane kicking on. This is a Coleman furnace. Is this possible and if so, how ...
0
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1answer
67 views

Which is better indirect or tankless hotwater heater

I am in the process of getting my boiler and hot water heater replaced. One company gave me a quote for a Weil McLain boiler and indirect hot water heater. Another company gave me a quote for a bosh ...