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

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19 views

baseboard heat problems it makes loud noises and does not heat 2 zones at the same time

The baseboard heat will heat the main floor and not the upstairs and vice a versa. What could be the problem, it also makes loud noises.
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157 views

Is it normal for this PVC pipe to be dripping from under the eaves?

I have a 2 story house, 14 yrs old. There is a PVC pipe under the eaves over a window on the 2nd story, that has been dripping more than normal the past couple of days. Our AC unit is located in the ...
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20 views

What type of control systems are available for a home with multiple HVAC systems?

Our new (used) home has two HVAC systems, one for upstairs and one for down. There is a thermostat in the dining room, which is directly affected by sun. And one in our bedroom, that clicks all ...
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11 views

old furnace and thermostat upgrade

In a furnace that has no circuit board, can the C wire be connected between the C terminal on the thermostat and to one of the contact leads on the 24V transformer and operate safely?
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1answer
105 views

The hot water is working but the radiators will not heat up!

We have a Utica Boiler model number SFH4150WT and we are receiving hot water but the radiators do not heat up!!. We tried bleeding the radiators, they only heated up a little bit but after about 5 min ...
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1answer
232 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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35 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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42 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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51 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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56 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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67 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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55 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 ...
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1answer
646 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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0answers
80 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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38 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
58 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
716 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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62 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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217 views

possible HVAC Selector Wiring Solution?

I moved into my current home last winter. This house has an old zone controller MasterTrol Mark V model Mabs-V-3. UPDATE: just found that all wires connected to M? end nowhere. So I remove all the ...
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28 views

Electric HVAC unit runs and stops randomly

I just turned on my heating unit for the season and it seems to be running and stopping intermittently. I'm not sure if this something to be concerned. This happened last season as well and I called ...
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0answers
100 views

Central AC is Icing up, but not cooling my house

My central air conditioner isn't cooling like it used to. I noticed that the refrigerant lines entering the evaporator coil in the plenum were icing up. What might the problem be?
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39 views

Why is my A/C's breaker tripping all the others?

I noticed the A/C wasn't coming on - even the outside compressor - so I checked the breaker and the two switches that the A/C is on were tripped. At this point no other breaker was affected. I went to ...
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269 views

Furnace not working properly with digital thermostat

I have been attempting to use several different types of digital thermostats to replace my old mercury thermostat, however none of them are able to control the furnace properly. All of them are able ...
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83 views

Which should I do first? replacing furnace or resurfacing concrete floor?

I'm going to get two things done in my basement soon (by hiring professionals), but I'm wondering what the right order of operations is. One task is to replace the gas furnace that sits near the ...
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2answers
77 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
586 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 ...
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22 views

Need to run a “C” wire to thermostat but control board has no “C” [duplicate]

I am looking to replace a thermostat with one that needs a C wire... which my current thermostat does not. I have some extra wires in the thermostat wiring that are unused... so I went down to the ...
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2answers
180 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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178 views

Thermostat replacement

My old thermostat is a carrier t-stat and has a jumper wire between o/w2* and L I am upgrading to a honeywell wifi t-stat, should I install the same jumper wire on the new thermostat? I have an ...
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2answers
2k 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
804 views

Can I wire a Bathroom Fan to two Switches in Parallel?

I want to control a bathroom exhaust fan with a wall timer, and a 24 vac relay. Basically both switches would be wired in parallel. Is this safe to do?
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2answers
143 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
107 views

What steps are required to convert R-22 Freon to a new R-410A Puron system?

I am house hunting in Houston. Every 2000-2004 house we've seen so far uses old A/C Unit and coils for R-22 Freon and not the newer R-410A Puron. Reference: ...
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1answer
1k 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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168 views

Why is my heat not shutting off at the set temperature?

When I turn the heat on on my central heat and air unit, the heat came on then continued to run getting really hot. It would not shut off unless I turned from auto to on then back. Sometimes I had to ...
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1answer
755 views

Do I need a sleeve for through the wall air conditioner in new construction?

I am about to buy a through the wall A/C unit for a small building, which the builder will frame out for the A/C. Is the framing enough, or do I need to buy a sleeve for A/C?
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0answers
1k views

Why would said gas furnace keep shutting off?

Seems that I have a gas furnace that is having some sort of heat/air sensing issue. Basically it shuts off after running for a minute or two. But if I remove the top plate of the furnace itself it ...
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0answers
222 views

Is it possible to insulate existing ducts without removing drywall?

My second story is always warmer in the summer and cooler in the winter than the ground floor. I've had the ducts cleaned and sealed and I've also adjusted the blower motor speed. It occurs to me that ...
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0answers
244 views

AC won't turn on after replacing thermostat batteries

we replaced the batteries on our thermostat after they began flashing for a few minutes. We'd been using the heater up to that point. After replacing the batteries, the heater does not turn on ...
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2answers
585 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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0answers
34 views

How can I determine if a valve complies to MSS?

How to know if the valve complies to Manufacturers Standardization Society (MSS) or not? I want to approve a valve for an HVAC project, but I don't know how.
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0answers
33 views

Is my heat pump's condenser fan motor bad? [duplicate]

The other day my AC stopped working. I'm thinking the condenser fan motor has gone bad (unit is ~10 years old). Here is what I did to troubleshoot which led me to believe it was the fan motor. ...
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1answer
2k views

How do I add a C/ Common wire to my “Specific” HVAC system? [duplicate]

I just bought a new WiFi thermostat that requires me to add a C-Wire at the furnace. I have read the questions related to my issue but would like a suggestion on my particular (incredibly OLD) ...
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1answer
590 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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1answer
469 views

Why isn't my thermostat working?

I have an old Lennox (gas heat only) thermostat. There are 3 wires coming from the wall. Black, yellow and a light blue color (could be a faded green or an old dirty white). The thermostat wouldn't ...
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251 views

Why isn't water running through our radiators?

We had a plumber in today to bleed our rads. He also changed the batteries on the thermostat and fiddled around with the boiler. Since he left the temperature has dropped dramatically and he's refused ...
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0answers
84 views

I have no furnace, only electric blowing heaters. How do I get ventilation?

I have a 100 years old building with a store on the main floor. Since the building was built over 100 years old there is no ducting whatsoever. There is also no furnace. In the summer we just hook ...
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4answers
6k 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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2answers
402 views

Connection for range hood from 8“ circular to 10”x3.5" rectangular

I am installing a new range hood for our kitchen. The duct exhaust at the top is 8" circular, but our old vent to outside is 10"x3.5" rectangular. I see what we could usually use a register boot but ...
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1answer
80 views

When is a variable-speed compressor HVAC unit worth the cost?

Surprise, its summer and our AC broke down. We were quoted prices for installation of the current standard (SEER 14) AC units (about $6500 unit cost and installation) vs Trane's SEER 18 AC units ...