Questions tagged [hvac]

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

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1answer
18 views

Replacing swamp cooler pads

I have a AercoCool Pro 4800 swamp cooler roof unit and need to get new rigid pads for it. Do the pads need be specific to the brand according to the cooler's spec sheet, or can I use any pad that is ...
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23 views

Upstairs is getting frigid at night during cool nights

I have a dual zone Lennox system, and it cools well, but for the past few weeks it seems to run away at random cooling the upstairs to several degrees lower than requested. We have EcoBee thermostats ...
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DIY Solarium / Four Seasons Room - Project Planning Advice

I am located in Columbus, Ohio. I currently rent, but I am planning on buying a house in the next two years, and I want to get started on planning for this project. My wife is a houseplant enthusiast, ...
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18 views

How to connect different HVAC components each with a blower

If there are multiple HVAC components, each has its own blower; for example: Furnace/heater with blower : for heating Air handler with blower : for cooling and dehumidifying, and (optional and if the ...
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0answers
60 views

Can I install an electrical outlet on furnace closet wall?

I'm remodeling my unfinished basement. I'm building a closet to enclose the gas furnace and water heater. Can I install an electrical outlet on one of the walls? This would be facing outward ...
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15 views

Drafts coming from all floor Heating system ducts. Gaps between sheetmetal and floor have been sealed

I had my heating system, crawl space furnace and leaky poorly insulated sheet metal duct work, replaced a couple years ago with a 96% efficient system. The system was independently tested and ...
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1answer
72 views

wiring hrv in a confusing house

some beautiful pictures first time posting apologies if my placement is off Buying HRV. I am debating between two units, venmar evo5-700 which doesn’t support furnace interlock or lifebreath rnc205, ...
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1answer
81 views

Installing a Nest thermostat without a C wire?

I am attempting to install a nest but do not have a common wire on my hvac unit, perhaps it is slightly dated. I have read that on older units the O terminal is the same as C and I can remove the ...
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51 views

Part on furnace making scratching noise

This spinning part on my furnace (not sure what the part is called) is making this scratching noise. When one section of the part hits the area behind it, it makes that noise. Any idea how I can ...
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1answer
100 views

How do I wire a/c if furnace wiring compartment has no y terminal?

I have been trying to figure this out for more than a year. All was running until HVAC company came to replace 2 thermostats with nest and rewired 2 HVAC units (a front of house and a back of house ...
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2answers
229 views

Plaster Walls Cracking above air vents

My house was built in the 1950's and have plaster walls. I am in the process of repainting and have noticed that the plaster above the baseboard air vents has cracked above almost every vent in the ...
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22 views

wiring up new air mover

I have a central air system and my squirrel cage fan inside the house started humming and then stopped. I figured it was the capacitor but I found a whole new fan for just a little more. Im having ...
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1answer
246 views

Sticky black liquid coming from Furnace / AC Unit

I have this sticky black liquid slowly leaking from my gas furnace / ac unit. I called an HVAC repairman and he wasn’t sure what it was. He said he thinks it’s an old drip pan made of tar (not sure ...
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11 views

Heating system cycling

My heating system is power cycling because the heat exhaust temperature sensor is tripping. When I turn the intake gas valve closed a bit, the system will stay on for longer but it's still does some ...
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72 views

Thermostats with or without variable temperature differential (swing)

I am looking at replacing my thermostat, and don't really need or want one with geosync. I am thinking of the honeywell RTH9585wf. Currently I have a lux that is not wifi but programmable. It ...
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23 views

AC compressor runs with heat on. NOT a heat pump

My AC compressor recently started running whenever the heat kicks on. It is not a heat pump. The compressor is a Nordyne fs3ba-036ka. I haven't done anything to the system aside from changing filters ...
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0answers
26 views

Furnace sometimes does not start

I have a 5 year old Broan furnace model M7RL 072A AW downflow condensing gas furnace. Here's the furnace startup sequence: pump runs ignitor glows hear the click of the gas valve opening fires up ...
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38 views

Very Old thermostat with TR wires

I want to buy a new smart thermostat, but am confused on the old wiring. I have single zone 120year old gas boiler (converted from coal, then oil, now gas). No cooling. The old honeywell thermostat is ...
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43 views

Suggestions on where to relocate a wall register I'm enclosing in a closet? (with labeled floor plan attached). Thank you!

I'm looking for some suggestions on where to relocate the HVAC wall register (shown in red), as I am planning to enclose it in a closet. It comes from 3x7 rectangular duct into the 2x4 wall and rests ...
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0answers
22 views

PTAC heat troubleshooting

I own a condo with two Islandaire EZ09EBMXH8N10AA PTACs, one of which is acting weird. They have self-contained A/C mechanisms, but the rooms are heated by pumping hot water from the building through ...
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1answer
118 views

Can I manually switch off booster fans that are coupled with HVAC blower?

Could not get upstairs in 1900 craftsman bungalow cooled with HVAC system until the contractor inserted a booster fan in each of the two ducts. Fans are coupled to the blower of the HVAC. Now in fall ...
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30 views

Lennox G51MP shutting down with Primary/secondary switch fault

I have Lennox G51MP-48c-090-06 ~14yrs old, starting up for first time this season. It is throwing error code: Primary or secondary limit switch open. Unit shows normal operation when powered up and ...
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126 views

No power to isolator switch

I recently moved into a repossessed flat and the electrics were a bit of a mess. Sockets, switches, etc. hanging off walls but it has since all been made safe/good by an electrician. The only thing ...
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0answers
26 views

Eliminate Humidistat

I have an old Honeywell H8808 humidistat and a Pro 1 model T721 thermostat and the problem is that when the humidistat is turned down far enough to kick the system on it will come down to set ...
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0answers
76 views

Why is my HVAC system not turning on the A/C compressor?

My AC stop cooling. Here's what I found. Inside blower is working, outside compressor/fan does not turn on. I manually push the contacts in the outside relay and the compressor and fan worked, used ...
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357 views

Only getting 15-16 volts from Furnace R and C

I recently purchased a smart thermostat. Because it needed a common wire and I only had a 3 wire setup, I ran a new thermostat wire to my furnace. However, I now get only 15 volts (inconsistently, ...
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1answer
2k 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 ...
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1answer
75 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 ...
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82 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 ...
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40 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 ...
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38 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 ...
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350 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 ...
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1answer
104 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 ...
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94 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 ...
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1answer
57 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 ...
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0answers
76 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 ...
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1answer
72 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 ...
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44 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 ...
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1answer
829 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 ...
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1answer
117 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 ...
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1answer
52 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 ...
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3answers
57 views

Furnance Drain Line Not Draining

Recently had a new furnace/ac/ductwork installed in our home. The furnace/air handler are located in the attic on the second floor of the home. A drain line is run from the unit to the utility room on ...
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1answer
34 views

Garage Vent Intake/Exhast

So I have a 1.5 car garage that seems to be sealed off, airflow wise pretty well. Any moisture from rain or snow just seems to sit and not evaporate at all or extremely slowly. Also, I dry out my ...
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1answer
87 views

Use CLR to clean stuck bleeder valve

I was bleeding the air out of hydronic heating zones and I notice some mineralization on bleed valve attached to my air scoop. I took the Schrader valve cap off and tapped the valve I noticed it was ...
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120 views

Controlling one FCU with two thermostats

I have a chilled water fan coil unit that will feed two areas, living and the bedroom. I want to control the FCU with two thermostats, one in the living and one in the bedroom, (preferably) in a ...
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1answer
57 views

What should my thermostat show when switching Heil furnace from winter to summer?

I will be ready to switch furnace from winter to summer tomorrow. It's a dual system/oil switches over at 32. What should it read on my honeywell thermostat when i switch it over. Help appreciated.
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1answer
698 views

Thermostat C Wire (Possibly Unconnected)

I purchased a Honeywell RTH6500 Wifi Thermostat, which requires a C wire. My old thermostat showed a connected blue C wire. However, it was battery-powered. If I removed the battery, the thermostat ...
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1answer
76 views

Connecting Common Wire to Control Board

I have a heat pump and want to add a thermostat that requires a common wire. I have read through many threads that show how to add a wire but I already have a few extra in the bundle so its not so ...
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0answers
35 views

U.s. boiler / Burnham boiler alterations

i have a 203ncl-tei2 boiler installed in danvers Massachusetts. Regular elevation. This boiler also has a failed tejurland (universal control) powerventer motor on it that is only humming, not ...
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1answer
69 views

Swapping to Hive thermostat. 4 wire communicator has 2 wires per post

I'd previously asked if I could swap my wires from the 4 wire communicator to the larger board and was told I could. I finally found time to do it. However, as I was preparing to move the wires, I ...

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