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

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3
votes
2answers
3k views

How can I calculate the Btus needed for a single room A/C unit?

How many Btus is recommended for a room about 35 square meters? I have 2 units with 13,000 Btus each. I'm thinking it should be enough, but the room is just so-so cool. I can never say it's COLD in ...
0
votes
1answer
105 views

AC unit (turned on year round) leaves so much ice in the blower causing no cooling (pic included)

My mother has asthma and tells me she needs the AC on almost year round. The AC unit is outside the condo we own, and it connects to the coils in the heater/ventilation system. We are experiencing ...
0
votes
2answers
336 views

What size A/C unit should I install?

currently using a Goodman 24000 BTU Central air, installed in '96. it is starting to cost too much because of leakage of refrigerant. I did the size calculator thing and it recommends a 30000 BTU ...
1
vote
3answers
328 views

Swapping out circuit board on York AC?

I have a York AC unit where the circuit board is shot, so I bought a replacement circuit board (same model). The model number for the board is 031-00251C. Pictures of old circuit board: ...
1
vote
2answers
3k views

What could be causing my A/C not to come on?

I had a thermostat get hot and smell, replaced thermostat. Still not working found fuse on control board blown replaced fuse. Lights on control board indicate no problems. Replaced 18/5 cable from ...
2
votes
2answers
2k views

Is a little ice on the cooling coils ok?

This is our first summer in a new house which has central air. It was a bit hotter today than normal so the AC was running for a long time. After awhile we noticed the airflow stopped because the ...
0
votes
3answers
1k views

A/C Runs non-stop and shuts down without reaching desired temp

I have had a repair man out 4 times and he says he can't find anything wrong with the unit. I cannot even feel air coming out of the diffusers unless I climb on a chair and put my hand right next to ...
15
votes
4answers
28k views

Why don't programmable thermostats automatically switch between “Cool” and “Heat”?

While I can set my house to be a particular temperature, I still have to manually switch it between "Heat" and "Cool" mode, and this seems to be true of every thermostat (programmable or not) that ...
1
vote
1answer
7k views

What causes a HVAC control transformer to overheat?

I recently replaced my 24 volt HVAC control transformer. The outside unit started up including the air handler and ran for maybe 10 minutes. After the units shut down I noticed that the transformer ...
4
votes
2answers
4k views

What are these two pipes coming out of the house?

I am trying to figure out the purpose of a couple of pipes that are currently coming out of the house. First, a couple of notes: One-story house. HVAC system is in the attic. It is winter here. ...
0
votes
1answer
567 views

Can I fill this AC line inlet with expanding foam?

I think the PVC inlet for my AC lines is a possible entryway for mice getting into my attic. Is there any reason I shouldn't fill it with expanding foam to seal it off? Or is there a better, less ...
0
votes
3answers
149 views

Will high efficiency furnace plumbing lead to cold air entering the house?

At the outside wall of my house I can see two white PVC round tubes/pipes, I understand one is for sucking air from outside, and one is for furnace blowing warm air to outside - correct? We are ...
0
votes
2answers
278 views

how do I keep leaves and foreign objects out of the top of my a/c unit?

Is it possible to make a lid that is light enough for the air coming off the fan to raise it attached with hinges so it drops back down when not in use. This would keep debris from getting inside, yet ...
0
votes
1answer
1k views

How well does a single A\C unit provide 2 zone cooling?

My 2,900 square foot house currently has two separate AC systems (one upstairs, one downstairs). They're both very old and need to be replaced. One of the four HVAC salesman that provided quotes ...
0
votes
2answers
1k 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?
9
votes
5answers
15k views

Why won't HVAC supply stores sell directly to the public?

I am quite shocked that every store in my very large metropolitan area that sells HVAC supplies requires purchasers to have HVAC contractors license. Which makes it very difficult for a very ...
0
votes
2answers
1k views

Can I install whole house humidifier in AC ducting?

Just grabbed 2 Honeywell whole house humidifiers: HE360A1075. It's the best model Lowes has and recommends. I have 3 floors and a basement in an old (1890s) victorian house. We have cast iron ...
1
vote
1answer
360 views

How to maintain temp for always cold office in finished Basement

I work out of my home in an office in our finished basement. The room is always cold whether it's the middle of winter or the middle of summer. I often run a cheap space heater (especially) in the ...
0
votes
1answer
2k views

Need help running and connecting a 'C' wire to my new thermostat [duplicate]

I have a Laars gas boiler that has 3 heating zones; basement, 1st floor, and 2nd floor. I want to replace the old mercury honeywell tstats on the 1st and 2nd floor with newer honeywell RTH9580 wifi ...
0
votes
1answer
639 views

How should I attach a C wire on my chromalox boiler?

I have a chromalox canada boiler model EDB-2. Recently I purchased a wireless honeywell transponder and thermostat, and am trying to install them. I currently have W and R wires but am missing a ...
0
votes
3answers
58 views

Can forced central air be retrofitted with central humdifier?

Several homes I'm considering have central air conditioners, but radiators or baseboard heaters. Is it possible to use the A/C ductwork to provide humidity to the home? I assume most central ...
1
vote
0answers
36 views

How can I reduce the noise from an HE boiler vent?

I have a HE boiler that is direct vented out the side of my house on the neighbors side, they find the 'roar' of the exhaust to be very annoying. Have anyone tried troubleshooting these to ...
0
votes
2answers
899 views

How to Calibrate a Make-Up-Air Controller?

My home is equipped with a make-up air line intended to bring some outside air to mix it with indoors air prior conditioning by the furnace. I am not sure why this is necessary but my question is ...
4
votes
2answers
92 views

Resources for designing new HVAC [closed]

Our house is a bungalow with full basement and is currently heated via electrical baseboard heaters in every room. I'm converting this to a central air system heated by a gas furnace, and possibly ...
0
votes
1answer
249 views

Should I remove existing drywall before framing a wall around HVAC ducts?

My friend has soft AC ductwork running up an interior wall. He wants to build a wall around it to hide the ductwork. My idea is to pack out the wall by nailing in framing between the ductwork right ...
0
votes
1answer
5k views

Quieting cold air return vent

My gas furnace is in a dedicated "closet" inside the utility room. The closest cold air return is about 5' away (laterally) in the ceiling of the hallway right by the bedrooms. When the furnace ...
0
votes
1answer
10k views

Wireless Thermostat C-Wire Substitute

I've read How can I add a "C" wire to my thermostat? and checked out the Venstar Add-A-Wire Accessory. I've watched Honeywell's YouTube video on "DIY Wi-Fi Thermostat Substitute G-Wire for C-Wire," ...
1
vote
1answer
1k views

How to wire a new Honeywell RTF6580WF thermostat to replace a Chronotherm IV?

I have an old Honeywell Chronotherm IV thermostat that I am trying to replace with a Honeywell RTF6580WF wifi thermostat. I have a gas furnace and an air conditioner. Wiring for Chronotherm IV ...
0
votes
0answers
124 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: ...
1
vote
0answers
207 views

How can I install a furnace register in a kitchen-cabinet toe kick?

I'm planning to install new kitchen cabinets. I'll be covering up the kitchen's existing sidewall diffuser with new cabinets, so I'd like to relocate it to a new register in the toe kick of the sink ...
2
votes
2answers
798 views

Is Flex Duct Safe To Use In A Crawl Space?

The home I purchased has a crawlspace below an addition that was put on to the original structure. The HVAC contractor that did the work ran 2 long runs of flex-duct to the 2 registers in the room of ...
0
votes
1answer
2k views

I have just reset furnace due to a trouble code, what should I monitor or re-do over the next few days?

My furnace was throwing a trouble code. The code was 31 and for my manufacturer (Bryant) and others thats is a pressure switch code. I was able to resolve this code and get my heat back on simply by ...
7
votes
2answers
11k views

Why are almost all of my house's HVAC floor registers placed near exterior windows?

My current house is a single story built over a crawlspace and all the HVAC registers are in the floor. In all of the larger rooms, at least one (and usually more) register was placed near an exterior ...
0
votes
1answer
258 views

How can I prevent my furnace exhaust pipe from freezing?

My furnace keeps on turning off because my air intake freezes. The reason it freezes up is because my neighbors exhaust vent blows directly on it. What can I do to prevent this?
2
votes
1answer
12k views

Which way does the air flow through my furnace?

Below is my furnace and I need to change the filter however I am unsure which way is the airflow direction. Red or Blue?
0
votes
1answer
185 views

Does HVAC lineset need to be grounded?

My HVAC contractor says the installation of the line set between the air handler and the condenser outside is complete but he has not grounded the lines. Do HVAC copper pipes need to be grounded?
2
votes
1answer
279 views

Is my Heat pump and gas furnace installation incorrect?

I moved into a house about 2.5 years ago, and the previous owners had a heat pump installed, together with a gas furnace. Recently I had my furnace repaired (faulty igniter) and the HVAC technician ...
0
votes
0answers
252 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 ...
3
votes
2answers
2k views

Can 2 - 6“ flex ducts be combined into a single 8” rigid duct

I'm trying to clean up some sloppy HVAC work in my home prior to finishing my basement. I have 2 VERY long 6" flex duct runs coming off the supply master that feeds the great room in my house. Both ...
2
votes
1answer
788 views

Is the furnace undersized?

I have a 2700 sq ft rambler home with cathedral ceilings over a large portion of it - over the hallway, 2 living rooms and kitchen. We replaced the furnace that was installed when the home was built ...
4
votes
4answers
2k views

Can I reduce static pressure in one room by adding a vent to an adjoining room?

Our return vent for our hvac is right outside the master bedroom. The master bedroom gets very little airflow with the door shut. It was recommended that we add secondary return duct in the master ...
0
votes
1answer
1k 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?
1
vote
4answers
1k views

Is there a special low temperature thermostat?

I have a gas ceiling mounted furnace for my garage. I want to set my garage at 35-40° F (1-4° C). Is there a special thermostat to control furnace at that low temp? (I've seen one works as low as ...
1
vote
1answer
275 views

Bathroom, dryer and central vac - Can any of the exhausts be combined, and can any use the same penetration?

I have these three units within 5 feet of eachother. The place where the bathroom vents to is the only place within reach to have a penetration to outside. My options are to stack these three ...
0
votes
1answer
392 views

Thermostat C-wire replacement using a wall socket?

I have a Filtrete 3M WiFi thermostat. As expected, it takes a C wire, which my apartment doesn't have and the apartment maintenance folks wont' let met wire either. However, there's a wall socket ...
2
votes
1answer
479 views

Breaker box or heat pump problem?

We ran our forced air heat pump today. 15 min. in we noticed it just stopped running. Looking in the breaker panel I could see that the breaker for the heating unit had tripped. When I tried to ...
1
vote
3answers
733 views

Should I leave the fan switch on my thermostat set to fan rather than auto?

I purchased a new Amanda Furnace in Oct'2013. I am told in order to maximize a warm, consistent room temperature I should set the thermostat to the Fan position rather than the Auto position. Does ...
4
votes
2answers
4k views

Is voltage too high in C wire going to thermostat?

I've managed to add a C wire to my thermostat. I then decided to check the voltage between the R and C wires, and find that it read as 27.8 volts, not the 24 volts it was supposed to be. Could this ...
0
votes
1answer
7k views

When should HVAC returns be opened and closed?

My Pennsylvania house was built in the early 90s, has central heat (natural gas) and central A/C, and most rooms have pairs of closable air returns on the wall near the floor and ceiling. I've been ...
0
votes
1answer
46 views

Why isn't my aircon blowing cold air?

I have 2 x 9000Btu split aircon installed in my house three days ago. In fan mode it works properly but when I switch to cooling mode the upper pipe from the outside unit freezes immediately, not cold ...