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

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1answer
301 views

How do I connect my whole house humidifier to my furnace?

Connecting Desert spring Humidifier to the furnace: Do I eliminate the 24V transformer that came with it? The furnace Keeprite has the the electronic board says Humidifier W1 and C. where can I ...
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1answer
49 views

Adding a “C” wire for a wireless theromstat [duplicate]

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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1answer
75 views

How can I remove ductwork that is butted against a foundation wall?

I need to remove the existing ductwork in my basement to install insulation behind it. I'd like to do it without destroying the ductwork. The vertical duct is right against the foundation, so I can't ...
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0answers
131 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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0answers
19 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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1answer
47 views

Why won't my electric furnace kick on unless the thermostat is set to 73?

I have an older, ill insulated mobile home. My house is obviously not 73 degrees, and my heater will not kick on. I set it to 73 and it finally came on, but then the furnace would not shut off. It ...
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1answer
260 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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2answers
2k views

How do I disable a thermostat to prevent it from turning on the AC?

I need to disable my thermostat from turning on the AC. Yes, covertly. I think one of my housemates is missing his native Antarctica. So, the thermostat still must be active & setable, but I want ...
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1answer
28 views

What would cauase a limit go bad in a furnace?

On Christmas day my furnace pilot would not kick on and the blower just kept running on and on blowing out cold air. A furnace tech came out and looked at it. He said the Limit was bad and he replaced ...
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5answers
10k 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
244 views

Carrier 60,000 BTU 92% Furnace vs Carrier 40,000 BTU 95% AFCU Furnace

I have about 900 finished square feet in my house, and I'll eventually be adding another 200 or so finished sq/ft in my basement. I'm looking to get my furnace replaced and have been quoted two ...
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1answer
93 views

When to Replace UV Bulb in AC System?

We had a new AC system put in last summer. The contractor included a UV bulb between the cooling area and the supply fan. It's supposed to kill bacteria and other nasties in the air. (The bulb is ...
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2answers
940 views

HVAC air handler with a built-in humidifier

I am in the process of choosing an air handler to use only for AC. I plan to keep radiant heat. However, in the winter, I would like to use the AC system to blow humidified air to compensate for the ...
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0answers
42 views

Should I look into getting an active or passive whole-house humidifier?

My wife and I moved into our place a few months ago. Now that is is winter, the humidity levels dropped down to 20% throughout the house. We want to install a whole-house humidifier to raise it up ...
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3answers
358 views

How to measure air flow coming out of registers?

As my contractors finish installing ductwork and the air handler for my central AC system, I would like to have a measure of how many CFMs come out of each register, as a function of how the system is ...
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0answers
44 views

How to clean carbon build-up on Honeywell whole house air purifier made of aluminum?

Bought a house recently that has a Honeywell F300 whole electric house air purifier/cleaner. The cell's aluminum fins have a black baked-on dust that I expect is preventing the unit from working as ...
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2answers
5k views

How do I connect the common wire in a Carrier air handler?

I am trying to install a new wifi thermostat in my home and need to locate the common terminal for my air handler. I have a Carrier model FB4CNF030. It's a new construction home and I have the blue ...
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0answers
10 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
104 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
372 views

What could cause a condensing units fan to stop working?

My AC unit fan stopped working suddenly. I tested the 3 pole condenser (capacitor) and the it looks OK ( 45 uf , 5 uf is what is mentioned in the spec of capacitor). I tested the resistance in the the ...
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2answers
69 views

How do I find air vents that are covered over with popcorn ceiling?

My house has several areas where we are have no heat vents and these areas are quite cold. Others areas have vents even in the closet spaces. I found one covered vent after walking through my ...
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3answers
7k views

Ethernet cable instead of Thermostat wire?

I need to pull new wire from my furnace to my thermostat and was wondering if there would be any problems in using an Ethernet cable instead of standard thermostat wiring. The reason being is I have ...
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3answers
5k views

Does a whole house humidifier go on the intake or outlet of the furnace?

On what side of the furnace do I install the tank of the humidifier (the warm side or the return air side)?
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0answers
45 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 ...
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1answer
45 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
172 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. ...
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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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0answers
41 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
32 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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5answers
105k 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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0answers
44 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
476 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, ...
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1answer
53 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
23k 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 ...
3
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1answer
352 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
49 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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0answers
74 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
104 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
66 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
53 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 ...
3
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1answer
5k 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 ...
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1answer
92 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 ...
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2answers
18k 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
142 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
108 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
239 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
523 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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1answer
170 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
23 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
348 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 ...