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

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5
votes
7answers
36k views

How much less power does a three-phase air conditioning unit use than a one phase 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
votes
0answers
28 views

Smart Thermostat C-Wire wrong voltage

I'm looking to upgrade the thermostats in my apartment to ones which I can control programmatically over WiFi. I opened up one of the old thermostats and discovered I have the classic "C-wire" ...
0
votes
1answer
43 views

electric heater keeps needing to be reset by turning fan on and off atleast every 1-2 days

My electric furnace is about 23 years old, it quits working but does not trip a breaker. It feels warm to hot at furnace and just kind of clicks occasionaly when I turn thermostat up to 90 to try and ...
0
votes
1answer
23 views

I have an electric furnace that sometimes blows cold air

I have an electric furnace that blow cold air sometimes. I replaced the thermostat and that did not fix it. The fan blows fine. If I shut if off for a few minutes and then try again, about half the ...
0
votes
1answer
165 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 ...
1
vote
0answers
13 views

Furnace added to second Floor

I am ripping my entire house apart and will be making almost an entire wall out of windows and doors,(glass). I will be changing all of the floor plans, (walls), so at the moment I am adding HVAC to ...
3
votes
2answers
171 views

Can't get my AC to turn on at all

Recently our AC stopped working. The thermostat is working properly, but the unit just started blowing hot air. I've never worked on a AC before, but I was trying to save some money. Anyway: I ...
0
votes
1answer
39 views

Oil furnace fan won't shut off when “heat” plug is connected to control board

I was changing my thermostat and I attempted to make the swap live without turning power off. When I connected new thermostat, the fan kept running. Ruled out bad thermostat and wire short by ...
1
vote
1answer
99 views

New Thermostat installed but compressor comes on immediately

I have a new Insteon Thermostat that I'm using to replace my prior Honeywell t-stat. This is installed to a relatively new HVAC system (both AC and Heat) that DOES have a "c" wire. I've attached the ...
0
votes
0answers
11 views

ac unit and thermostat

I replaced the fan motor and the capicators and the thermostat but the fan still don't shut off and continues to run after the thermostat has stopped and the fan gets very hot and l have to shut it ...
1
vote
2answers
100 views

Furnace fan works properly intermittently

My furnace fan sometimes stays on and runs continuously. I can stop it by flipping the breaker for the furnace on and off. It then stays off. When heat is called for, the fan comes on again and ...
0
votes
2answers
25 views

What would make my ac unit hiss

I live in a mobile home and my central ac unit starting hissing pretty loud 3 days ago and tday it is blowing only warm air. There is no water or ice inside or out. The outside unit is running but it ...
0
votes
1answer
1k 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 ...
0
votes
2answers
176 views

Issues after capacitor replaced on AC unit

Had a checkup on my AC/ furnace a couple weeks ago. The technician said the capacitor leaking oil and not pulling enough amps. He recommended me getting a whole new system. (My house was built 6 yrs ...
4
votes
1answer
57 views

What inspections/maintenance should be done before first air conditioning of summer?

I'm a typically handy guy who knows his limits. I recently moved into a new house so am unfamiliar with the history of the equipment. Before I switch the thermostat to A/C for the first time this ...
0
votes
0answers
16 views

Reducing AC vent/diffuser

I want to add some smart vents to my home control system. The thing is, the largest size that they come is 12x6, and my current ceiling vent/diffuser is 12x12. I would prefer not to have to go into ...
0
votes
1answer
72 views

Less than 24 volts on the thermostat C wire

We have a brand new air handler at work, but the thermostat is mounted on a wall next to a server/computer room which is always warmer than the rest of the office. I want to install a thermostat that ...
0
votes
0answers
25 views

Random Outages on only 5 of my breakers. Open/ Bad Neutral?

Every morning when dawn comes around (5:30 - 6:30 am) the power on 5 breakers in my house seem to kick on and off with power. The breakers are my water heater (electrical/ no gas), my a/c, my kitchen ...
7
votes
5answers
47k views

How much cooling can I expect from a central air conditioner?

Yesterday's high was 106.0F, low of 79.2F, full sun all day. AC set at 78F, indoor temperature reached about 85F. Today's high was 105.4F, low of 81.1F, full sun all day, now about 102 at 7pm. AC ...
0
votes
1answer
20 views

How long should a heat pump last before needing repairs?

We have a Goodman heatpump Model: SSZ140601 Model Desc.: 14 SEER HP, 5 TON Mfg Date: 6/3/2010 First of all, we did not register the unit so that cut our warranty in half. Two weeks ago, our ...
2
votes
7answers
88k views

Why won't my A/C turn on after I replaced the thermostat batteries?

Our thermostat died yesterday, but after replacing the dead batteries with fresh batteries, and confirming the LCD screen was operable, our AC no longer turns on. I have attempted a factory reset on ...
2
votes
1answer
84 views

What components need to be changed when upgrading from R22 to R410a?

What equipment will change when I convert from R-22 to R-410A? I don't want to get rid of my current heater as it's a hydro-thermal unit that uses free heated/recycled hot water. Can I get away with ...
1
vote
2answers
286 views

Trane xv80 3 blinks

Trying to be as thorough and concise as I can, zero experience with hvac. I have a year 2002 Trane xv80 that is giving me the three blink code, which indicates a pressure switch issue. I ...
1
vote
1answer
42 views

Limit switch doesn't function on oil furnace

my limit switch on my oil furnace does not shut off the burner when it hits the limit.I replaced the limit twice maybe I had a bad one still no luck . While furnace was running I took the thermostat ...
4
votes
6answers
5k views

Do I need to level the outdoor AC cooling unit?

I've read somewhere that the outdoor AC unit needs to be leveled. My outdoor unit is a bit slanted due to the floor not being completely flat (pic below). However, I don't see any obvious structural ...
1
vote
1answer
33 views

Why might a thermostat refuse to switch from Heat mode to Cool mode?

I have this Honeywell RTHL2410C programmable thermostat and typical Florida electric AC system. Starting this Spring, it has started behaving strangely when switching from Heat to Cool mode. The ...
1
vote
3answers
66 views

Duct sizing impact on flow

We have a ranch with a wood fireplace in the living room. It's fantastic at heating the main living area, but the bedrooms down the hall get left in the cold. I'm going to install insulated flexible ...
1
vote
1answer
482 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 ...
0
votes
2answers
36 views

A/C unit cycles on and off

My outside compressor / condenser is cycling on and off, even though the thermostat is calling for A/C. The blower in the house still runs, and the thermostat is working properly. ( I opened up the ...
0
votes
3answers
165 views

One portable air conditioner - want to use it in two rooms

I have a Kenmore portable air conditioner model - 408.72012. this particular model can be housed on the outside of the building and the A/C air is vented into the inside space (normally through a ...
0
votes
1answer
26 views

Need to find control valve for damper

There is no control valve attached to this damper: so I can't turn it to open/close the duct. It's currently closed :-(. It's smooth so I haven't found anything that can even grasp onto it tightly ...
0
votes
1answer
27 views

Does a central A/C with copper lines that are too small cause compressor and diaphragm failure?

I have a 3 ton R410A A/C unit that is 8 years old and is using copper lines that are too small. Does this cause leaks, diaphragm failure, and compressor failure? The air was not blowing cold, so I ...
1
vote
3answers
69 views

What's the most cost effective way of ventilation automation given no prior knowledge in the field

I have 3 fans for air inflow, and 3 fans for extract, all in one big hall. Currently I set the power of their motors with dimmers myself, looking at CO2 and temperature readings. I want to replace ...
1
vote
1answer
290 views

Anyway to hack a portable AC unit to cool 2 rooms [duplicate]

I am looking to take a portable AC unit and hopefully run a tube through a wall in another room while still cooling the room the unit is located. I have searched to attachments that could help but ...
1
vote
1answer
216 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 ...
0
votes
1answer
45 views

Could a leaking boiler be fixed?

I'm having a leaking hole in the cast iron boiler tube so does it mean that its time for a new boiler or is there any way it could be permanently fixed?
0
votes
0answers
32 views

Should I have a ceiling fan whose blades extend to the register?

Currently, the ceiling fan fixture and the 10x6 register are spaced by about 32" (~2 stud lengths). The room is about 350 sqft. Should we purchase a 70" ceiling fan so the blades extend out past the ...
0
votes
3answers
99 views

In what circumstances would an AC produce no condensate but still cool the air?

In what circumstances would an AC produce no condensate but still cool the air?
1
vote
1answer
126 views

How to connect thermostat to newly-installed condenser/evaporator unit

I installed a furnace evaporator and condenser brand goodman 4 ton unit but need to know how to connect thermostat from condenser to the furnace to the thermostat if any suggestion.
0
votes
3answers
43 views

Cooling radiators in summer?

How efficient would it be to use radiators circulating with cold water, to cool house in summer? Wondering if anyone has tried this, and how well it works? I was thinking about H/AC in general, and ...
1
vote
1answer
126 views

How to Change Chinese HVAC Thermostat

I am looking to put Nest thermostats in the house, I have now found out my entire house (one in each room, 6 of them) has been wired with HVAC Chinese U12A UNIVERSAL A/C CONTROL SYSTEM urrgh – they ...
0
votes
1answer
16 views

My home air conditioner that's inside the house, seems to be sputtering when coming on. What could this be?

My home air conditioner inside the house; when it's going thru its normal cycle of off and on, it seems to be sputtering and/or hesitating to come on. It's like or similar to a car that having a hard ...
0
votes
1answer
259 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?
0
votes
1answer
31 views

help with improving HVAC performance on the second floor of an old house

I'm hoping some of you can offer some advice on how best to add a second AC in our home -- or on whether we should look for a different solution. I should say upfront that I've done a lot of reading ...
1
vote
1answer
39 views

Replace insulation in a Trane HVAC? (TWE030C140B0)

I found a little mold on the foil covering the insulation in my TWE030C140B0 air handler/ AC/Heater. I am 95% sure I have the moisture problem resolved and now I need to replace the insulation. Does ...
0
votes
0answers
20 views

Cleaning of TempStar air conditioning parts

It's been 6 years since I bought the Tempstar 4 ton a/c. So far, it is running okay. But when the need arises, I want to be BOLO and do the repairs myself. So, how do I clean a TempStar a/c ...
0
votes
1answer
41 views

How long should it take to a 1.5 tons AC to cool down a 2000sqf house from 80F to 77F?

I know that it might depend on a lot of things like: -how air tight is the house -how old it is (insulation, windows etc) -what windows are installed -BTW I have casement window -outdoor temp (...
1
vote
1answer
26 views

Does the air temperature outside at the time of spring inspection matter when the tech comes to inspect and clean the inside and outside units?

I have semi annual inspections done on my A/C units both inside and outside. Will the temperature outside effect the tech's ability to properly clean and evaluate the operation of the units? The ...
0
votes
1answer
24 views

Are HVAC Transformers Interchangable (if their power ratings match)

I'm troubleshooting the blower not starting in a friend's HVAC system. We think the issue is either a) a blown transformer, or b) the relay that controls the blower has blown. The next step is to ...