Questions tagged [hvac]

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

373 questions with no upvoted or accepted answers
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5
votes
1answer
192 views

Adding a C wire to older 3 wire

How do I use the green wire as a C wire as suggested in most installation instructions for the newer wi-fi thermostats? They all reference terminal strips at the furnace, all I have is the 3 wire ...
4
votes
1answer
107 views

Is this HVAC condensing unit platform acceptable/stable enough?

Our contractor just installed a new A/C system and he built this platform outside our house for the new condensing unit. It looks like it is a 4" concrete slab sitting on top of brick "legs". Looks ...
3
votes
1answer
50 views

Furnace Connect G Wire

I have a dual energy electric/oil furnace that is wired to a thermostat with 2 wires R and W. I don't have any AC. Inside the furnace there is a switch relay to control the fan but it is not connected ...
3
votes
0answers
39 views

Why isn't my furnace igniting?

I noticed cold air from my Carrier 58SS furnace. The main burners were not lighting. The pilot flame was strong, but yellow. When I tapped on the gas valve, the pilot shut off. I removed the pilot ...
3
votes
2answers
76 views

Thermostat White-Rodgers 1F82-261 switches to stage 2 heat for no apparent reason

I am running a central heat system that uses a heat pump as stage 1 and a gas furnace as stage 2. The thermostat used is the White-Rodgers 1F82-261 which supports 2 stages of heat. When using regular ...
3
votes
1answer
165 views

Can a motorized damper be installed inside existing ductwork?

My HVAC system consists of a fan, furnace, compressor-driven AC, and evaporative cooler. The problem is that there is a large air volume used only by the evaporative cooler that is generating a lot of ...
3
votes
2answers
242 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 ...
2
votes
0answers
15 views

Trane HVAC in horizontal position - why does evaporator throw condensation?

I appreciate assistance from anyone who has had or understands the problem. I have a Trane HVAC system in a horizontal "left" flow configuration in the attic. Ambient temperature is about 95 ...
2
votes
1answer
52 views

Another “How do I add ”c" wire to boiler for Nest

I have tried searching this forum and others, but I could not find anyone with a situation like mine. I thought it better to ask here, rather than damage something. I have a Lennox wall mounted ...
2
votes
2answers
74 views

Should I insulate metal duct work in basement?

I have a balloon frame house with an unfinished basement. The air handler and furnace are in the basement too. Last fall, we had the duct work removed because it was wrapped in asbestos tape that ...
2
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0answers
79 views

Junction Box Blank Cover in HVAC Duct

I am starting a bathroom remodel second story that requires a length of NM wire to be lengthened by a few feet. I realize I can't do this hidden in a wall or floor and need this done in accessible ...
2
votes
1answer
67 views

Solar panel as a hatch and Is sleeping under a solar panel safe?

I'm looking to build a very large custom roof hatch/vent on my van. I was going to make to top out of Lexan, but then I realized I might want a large solar panel on the roof as well. I was looking at ...
2
votes
1answer
202 views

Ecobee Smart Thermostat- Using Room Sensor as primary control

This is ultimately a fairly simple question about the Ecobee3 thermostat and the wireless room sensor functionality, but I'll explain my situation first. Twin home, 2 stories + finished below grade ...
2
votes
0answers
60 views

Mini-split HVAC in new build?

Next few weeks I will be in the process of getting quotes for mini-split HVAC system. Curious, if anyone has gone ductless and if so, how is that working out? The house will be a a two story build(...
2
votes
0answers
55 views

Replacing a motherboard on a Carrier 8000VS Furnace

Hi guys, I am trying to finalize the wiring of my new carrier motherboard. I have about four more wires to connect and the new motherboard is slightly different than the old one. The pictures I’ve ...
2
votes
2answers
200 views

Lennox G23Q3/4-100-2 And Ecobee4

**Pictures attached to go along with my rambling explanation I have my Lennox G23Q3/4-100-2 natural gas furnace and my central air system that has been working since 1995 on a basic programmable ...
2
votes
4answers
2k views

Why does my furnace turn off after a few minutes, then re-ignite?

I have a Goodman 80% furnace in my barn dated 1999 it runs for about 5-10 minutes then flame kicks off for about 2 minutes and re-lights. It does not go into lockout mode (keeps cycling this way). ...
2
votes
0answers
1k views

Difference Between Take Off and Starting Collar - Which One Should I Use?

I am in the process of installing a whole house humidifier. I am planning to mount it to the supply side and need to connect the bypass to the return. I'm not sure if I should be using a take-off or ...
2
votes
1answer
524 views

Can I install a heat-recovery ventilator (HRV) in a garage?

I am building a high efficiency home in N. Minnesota, 2x6 construction, slab heat, spray foam insulation etc. Need to install an heat-recovery ventilator (HRV) unit, but only have space for it in the ...
2
votes
0answers
443 views

Installing Ecobee3 with Trane Furance

I am installing an Ecobee3 and have found that, while the common wire exists, it is not connect to the furnace. The wiring schematic for my specific furnace can be found in this PDF There is no ...
2
votes
2answers
115 views

Misbehaving/inaccurate thermostat?

I have a portable air conditioner/hvac and I'm having issues with it in heating mode. It's actually summer where I live but it was somewhat chilly as a storm passed over so I wanted to test heating on ...
2
votes
0answers
6k views

Increasing gas pipe size from 1/2“ to 3/4” at appliance

I'm planning to purchase and install a new condensing tankless water heater (Takagi T-H3J-DV-N) that will supply both domestic hot water and space heating (radiant via heat exchanger, separate closed ...
2
votes
0answers
1k views

Trane Weathertron Stat to Honeywell RTH2510

I have a Trane Weathertron thermostat thst I am replacing with a New Honeywell RTH2510. This is a heat pump with auxiliary electric heat. The wires on the Tran thermostat are. R, T, O, G, Y, B, X2 ...
2
votes
0answers
69 views

Air handler for an AC in the attic collect about 1 cm of water in it before it is high enough to drain… problem?

My air handler in my attic won't drain water(because the hole is 1cm above the pan) until the water reaches that hole. Why is this setup this way. From what I have read, NO water should be in the ...
2
votes
1answer
767 views

Want to add a WIFI thermostat, but no 'C' wire… only 2 wires to each thermo

i have a 5 zone radiant floor, oil fired heating system. Each thermostat only has 2 wires running to it. i have a TACO SR506 switching relay that receives the wires from each thermostat and controls ...
2
votes
1answer
526 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 ...
2
votes
0answers
3k views

Reducing air conditioner compressor vibration noise

I have a two year old Carrier air conditioner with an outdoor condenser. The condenser sits on a plastic pad on the side of my house, and I have two--one for downstairs and one for upstairs. ...
2
votes
0answers
570 views

How can I insulate and elevate an A/C line set on a flat rubber roof?

The Scenario An apartment building with a flat black rubber roof. The A/C condenser is on a platform on the roof with an air handler inside the unit. The line set runs across the roof for about 20 ...
2
votes
0answers
857 views

What are good Relative Humidity and Temperature settings on an MHRV and are the settings related?

I need to configure the threshold Relative Humidity and Temperature settings on an whole house MHRV system. The way the system works is that if the RH threshold is exceeded the system increases the ...
1
vote
1answer
19 views

Fan on propane furnace not coming on

I have a Honeywell model number NHGK076AF01 propane furnace. It is about 15 years old. The problem started when I noticed the breaker had tripped and I had no heat. After resetting breaker, I tried ...
1
vote
2answers
38 views

Musty Smell in slab and block house

As my title states, I have a house that is on a slab and the exterior and most interior walls are block and covered with plaster. Since we bought the house we have noticed a musty smell that we ...
1
vote
1answer
77 views

Central Air is Blowing cold air outside

I change the capacitor and cleaned all of the coils inside the interior unit and outside along with the fins and the blades with a professional solution. I had the HVAC refrigerant filled. I cleaned ...
1
vote
1answer
33 views

HVAC Air Blowback

Furnace/Blower: Rheem R92PA0851521MSA Dual Zone System (Honeywell TrueZONE HZ311) - Honeywell M847D1004 Actuators Age of system: less than 2 years old including ductwork Ive noticed that if Zone 1 ...
1
vote
1answer
59 views

Why the noises in the new furnace?

A company installed a new HVAC system 2 weeks ago. The furnace model was new: 58TNOA110C21–20. I initially ordered 58CVA110-20 but they said it will be out of market soon in August. So they installed ...
1
vote
0answers
77 views

The new AC doesn't cool the house down like old unit, what can be the problem?

I had to replace my old HVAC because it was old and had a freon leak. The new unit doesn't cool down the house like the old system. The ac runs all day and it takes hours to get down to 72 degrees and ...
1
vote
1answer
23 views

3-zone HVAC (HZ432) one zone's a/c stops working when hot in afternoon

I have a 3-zone HVAC. All 3 zones a/c worked fine until recently. Now, in the morning, before it gets too hot, all zones still work fine. But in the afternoon, when it gets hot, the a/c to zone 2 ...
1
vote
0answers
34 views

Furnace blower cutting in and out during A/C use

Backstory: I fired up my air condition for the first time this season (single family house) and felt lukewarm air coming out of my ducts. When i went outside i saw that the condenser was not turning ...
1
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0answers
26 views

Separate Thermostats for Heating and A/C

I recently purchased a vacation home that has two thermostats for a forced hot air gas furnace and a separate A/C unit that shares ductwork. The A/C also cools better when both the A/C and furnace fan ...
1
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0answers
52 views

Does cabling between a mini-split indoor and outdoor unit need conduit?

I am installing a mini-split AC system where there are multiple indoor units connected to a single outdoor unit. For each indoor unit, there is a separate 4-conductor cable that connects to the ...
1
vote
1answer
53 views

Line to AC dripping at the furnace

My line from my exterior AC unit is dripping at the furnace. The dripping over time has caused rusting and we've had to replace the control board under it. It appears the root cause of the problem ...
1
vote
0answers
26 views

Problem connection C wire into Lennox Furnace

I would like to connect my new Honeywell WiFi thermostat (RTH6580WF1001) to a Lennox Elite dual Heater and Cooler system. I don’t have a C wire in my old thermostat. I have read online that I can ...
1
vote
1answer
32 views

Replacing A/C thermostat

I think that my mother has a bad thermostat. When the A/C is turned on, the furnace blower works but not the outside unit. However, when I press the contact switch (outside), both the compressor and ...
1
vote
1answer
28 views

Can I safely jumper between either G or Y and RC at thermostat panel to troubleshoot AC problem?

I'm trying to troubleshoot a non-functioning AC. The fan does not come on and there is no cool air/condenser does not run. My thermostat is a Braeburn. Three things I'd like to try for ...
1
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0answers
34 views

AC unit not turning on

My A/C doesn't come on when I set the temperature on the Braeburn thermostat very low. Also, the recirculation fan doesn't come on when I set the thermostats fan setting to 'on', as though the indoor ...
1
vote
1answer
41 views

Furnace with no “C” connection

I have a mobile home furnace. This furnace only has a 4 wire connection terminal, G,W,R,Y. I also have a condensing unit outside with the 24 volt 2 wires coming to the furnace. I know I connect one to ...
1
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0answers
40 views

Is one large whole house fan better than two smaller ones?

I'm having an addition put on my house and I'm considering the "Quiet Cool" line of whole house fans. The fans are quite expensive and price wise two small fans are almost the same price as one ...
1
vote
1answer
59 views

Converting I+ I- thermostat to 'standard' wiring

I've been replacing my thermostats with the RadioThermostat CT50, which reports to my home-brew home control/alarm system. I have a 3-year old AireEase 4-ton unit in the shop that has a Comfort Sync ...
1
vote
1answer
42 views

C Wire in Air Handler

Can someone please help me find where to connect a C wire for my smart thermostat? Here are some pictures with descriptions. It is difficult to get to the 24v connection in the back. My schematic ...
1
vote
1answer
142 views

What is this mysterious filter and purpose?

Behind the regular HVAC air filter and next to the duct, there is a filter area with some rough filter covering an additional smaller duct. Does anyone have any idea what it is and its purpose?
1
vote
1answer
34 views

A.c. fan outside not coming on

It started with the thermostat not going in on only fan. That night i go to turn the AC on and the condenser fan wouldn't come on so I took a stick moved the blades and it started . i thought its the ...