Questions tagged [hvac]

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

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1answer
13 views

intermittent compressor on elderly dual-fuel heat pump

I have a 23 year-old dual-fuel 2.5-ton heat pump; it is a split system, air handler and furnace in the crawlspace, compressor outside. I use it very little in the winter, mostly heating with wood; I ...
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1answer
20 views

Dual hose portable AC unit creating negative air pressure

I bought a dual hose unit because it's supposed to not create negative air pressure in the room, but I can definitely feel the air resistance when I go to close the door to the room it is in. When the ...
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0answers
28 views

High Efficiency Furnace vented through the roof. How screwed am I?

I'm investigating installing a central air system and in doing so it was brought to my attention that my high efficiency furnace may not be installed properly. I'm in a narrow semi without much ...
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0answers
10 views

Furnace Displays Heat Pump mode when AC is running

I have a new Trane S9X2 furnace I purchased this winter. I want to make sure that everything is setup correctly now in the cooling season. I noticed that the furnace displays "HP1" when the AC is ...
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2answers
211 views

Heat pump not working after rain

A couple weeks ago, I had a Goodman 3 ton heat pump split system put in. At 5pm hours today, I was outside near the heat pump and noticed that it was functioning properly. At about 6pm, there was a ...
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1answer
68 views

Second Floor Bedroom Little HVAC

I have one bedroom upstairs 2nd level that virtually gets no air or heat. The other 2 bedrooms have medium force. For the one bedroom in question, checking with your hand, you feel very little and I ...
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1answer
94 views

2 Air Filters in Air Conditioning Unit

My air conditioning system has a 2-layered (each 1") filter holder, definitely made for two filters. My idea, to improve the filter life and have the least air flow restriction, is to have the initial ...
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1answer
47 views

HVAC Adding a Common

Got a new Honeywell WiFi thermostat and need to add a common. Currently the 3 common wires per the diagram (BL, BK, GY) are wired to one side of the AC Unit. Is there an issue if I piggy back a ...
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2answers
59 views

What's the difference between commercial and residential tankless water heaters?

I'm trying to figure out the difference between two tankless water heaters, produced by the same manufacturer, one a "Commercial" and another a "Residential". The commercial one is allowed to be used ...
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1answer
47 views

Mold at Air Return

I have 2 HVAC units, one for upstairs and one for downstairs. When I went to change my air filter for the downstairs unit I noticed some mold in the return duct. This is a large duct that travels ...
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0answers
12 views

Connect two LP-GAS High-Eff +95% Furnaces to one LP Tank

Connect two LP-GAS High-Eff +95% Furnaces to one LP Tank will reduce supplier refill to one location on House. Furnaces 100K BTU and 60K BTU. To reduce refill to one location (currently two tanks on ...
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0answers
29 views
+50

Change to different condenser fan motor model?

I have an HVAC system that has a condenser fan motor that has gone bad. The motor is no longer available. What considerations do I need to make in order to replace the motor with a different motor? ...
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1answer
33 views

Central AC Is not Cold

My AC will turn on but will not blow out cold. I'm rebuilding the whole system, ductwork and all. I've shorted the thermostat's red (power), yellow (a/c compressor), and green (fan) wires together. ...
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1answer
84 views

Bad Limit Switch?

My Nest thermostat is not working and it says the red wire is not getting power. The gas company man poked around the furnace and thinks it is a bad limit switch. Question: can a bad limit switch stop ...
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2answers
10k views

Means of adjusting fan speed on Bryant gas furnace

My home is heated by a Bryant 359AAV furnace. The thermostat controls and indicates whether the fan is ON or OFF, but the furnace has a four-speed fan. I believe the installer set the fan on "HI" and ...
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2answers
348 views

Connect Wifi Thermostat to Goodman GMP050-3?

I'm trying to connect up a wifi thermostat to Goodman furnace, specifically the GMP050-3. I've done some reading on this but I'm still not quite sure how to go about it. Specifically, I'm not sure ...
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3answers
44 views

Can insects get into a house through the ducting?

I have a study that normally has the door closed and all the windows are very tight, modern windows, yet I keep finding insects, especially flying insects like lady bugs and wasps in the room. Can ...
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0answers
8 views

Rewiring for Nest Thermostat - Current ABCD Configuration Carrier

So I would like to use a Nest thermostat on my carrier system. I have the ABCD wiring configuration from current thermostat to the board on the furnace. On the attached image, you'll see three brown ...
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1answer
154 views

Why is my Heat Pump fan not turning in cold weather?

My heat comes on and you can hear the condenser unit come on as well. However the fan is not turning? The outside temp is 30 degrees? Is this normal? Can anyone share some wisdom on this? Thank ...
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1answer
69 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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1answer
28 views

Heat-pump style AC is not putting out cool air

I live in the Northern area of the US, and I have a heat-pump style AC unit. So there is an AC unit with big fan outside my house, and there is a furnace in my attic. I bought this house 10 years ago ...
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2answers
44 views

Minimum length of mini-split AC line

I was considering buying a cheap mini-split AC unit to cool a small room (10ftx10ft) over the summer now that we spend more time working from home. There are several units on the market. However I'd ...
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1answer
62 views

burners out of sequence with blower motor

I have a Bryant furnace plus 90 model #398AAW036060D. I just changed the blower motor. In the last five years I've changed the main board, inducer board, pressure switch, and cleaned the igniter the ...
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1answer
130 views

HVAC one unit Residential system dual zone forced air

Have a Residential system. One unit, dual zone forced air HVAC. 2 thermostats. Is this type of unit designed to run the heat downstairs, while running the AC upstairs at the same time? The house/...
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0answers
58 views

Need help connecting “C” wire, unknown red and white wire from one unit to the other

We are replacing our old thermostats (installed in 2006) with two smart thermostats. We have 2 separate units and thermostats. We have an unused blue wire (c wire) at both thermostats. We thought we ...
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0answers
35 views

Any way to reverse engineer split ac inverter compressor speed?

Summer has come and I've got myself an oversized inverter Air Conditioner (1.5 ton for 120sqft room) as suggested by some YouTubers. Details: Outdoor temp day: 43C, Night: 30/35 Relative Humidity: ...
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1answer
26 views

Blue star inverter spilt ac 1.5 tonn

In my spilt ac the big pipe in the outdoor gets freeze when running ac on low temperature but not frezzing when it running in higher temperature. What is the fault if the gas is low in the compressor....
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1answer
54 views

Why does this wall in my basement have so many vents?

I have a wall at the foot of my stairs that has 3 vents in about 5 ft of wall. One of them ducts straight to the HVAC system, the other two just open into the unfinished storage/utility (furnace, ...
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0answers
45 views

Cooling a Room with No Windows

I am trying to determine the most effective way to cool my bedroom which runs about 5 degrees warmer than the rest of the living space: Questions: What is the most effective way to bring the bedroom ...
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2answers
2k views

Where do I attach C-Wire in this old Rheem Air Handler

Trying to attach a c-wire to old rheem air handler for a cooling system only. System is so old I didn't see what I thought I'd see when I got up into the attic. In going over the pictures I think I ...
2
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0answers
28 views

Why would a wall-mounted AC unit with a digital thermostat seem to be reading outside temperature when the fan isn't running?

My apartment has a wall-mounted AC unit with a digital temperature setting, which works great, but it has a consistent problem where its thermostat appears to read much differently than the actual ...
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2answers
216 views

HVAC blower fan won't stop

FINAL UPDATE: I have found the culprit - the Nest thermostat itself. First, I disconnected the t'stat at the control panel and found out that the fan would no longer start upon powering the system. ...
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3answers
920 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 ...
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1answer
72 views

1999 Goodman furnace modeld GSMS060-3

Furnace goes through the normal start up process but after 5 minutes the flames go out and I hear a click in the induction motor not the main fan. What could I check. I have taken out the flame ...
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1answer
49 views

Goodman GMNT100-4 Unit- Blower Motor Works for Air But Not the Heat

I have a Goodman GMNT100-4 that air conditioner was working great. However, I recently turned on the heat. The system goes through all sequences fine until it's time for the blower motor to kick on, ...
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1answer
51 views

Direct vent boiler exhaust exiting close to brick chimney

The exhaust vent for our Burnham Spirit direct vent boiler currently exits very near the junction box where I recently installed an IR-triggered motion-sensitive floodlight. The hot air is causing ...
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3answers
26k views

Can I cap the air return in my unfinished basement?

I noticed today that there is a massive air return in my unfinished basement. The opening is about 2 meters from the blower, and as large in diameter as the return duct coming from the upstairs. This ...
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1answer
24 views

Both reusable and disposable furnace filter?

I recently discovered that my furnaces (Rheems) have reusable "permanent" filters, but they also have a disposable filter tray. Are they intended to both be used simultaneously, or are homeowners ...
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1answer
610 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
24 views

Exterior air conditioning pipe insulation

I live in the Southern California desert and am doing some renovations to my house. Our AC line runs on the roof from the center of the house 25' to the west side and down the wall to where the ...
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2answers
41 views

Gas heater fan noise

I have a CF653C-H Cozy wall gas heater ..The fan runs fine , except when it shuts down , it clicks 15 to 20 times before stopping . At least I am guessing its the fan, could also be the motor ..But ...
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1answer
41 views

Why doesn't my HVAC system use the away temperature setting?

I have a Carrier Infinity dual-fuel 5 stage HP w furnace. I set the away temp much lower than the home temp but the HP keeps running to bring the temp up to the next home temp. I would think the ...
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2answers
269 views

A/C unit cycles on and off during cooling phase

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 ...
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0answers
15 views

Is PVC ventilation duct safe for health in long term? [duplicate]

Some contractor says PP is safer (the arguments is it is used in food packaging...) and PVC will degrade and release toxic materials after 10+ years. But in http://en.wikipedia.org/wiki/...
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23 views

HVAC Wiring Help

A little backstory should help... my parents built the house in 1996 with no central air. They added central air in 1999 and it was fine till three years ago. We had a programmable thermostat ...
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0answers
15 views

How to seal seams in a traditional Cedar wood dry sauna

I just built a new, indoor, traditional dry sauna made with Cedar wood. https://www.costco.com/almost-heaven-bluestone-3-person-steam-sauna.product.100485086.html During assembly, some of the ...
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3answers
88 views

A/C blower does not work after a power surge

My outside unit works but my inside unit does nit turn on, its a bryant a/c system. On the unit it says the circuit board is built into the blower motor. The transformer buzzes. Can I replace the ...
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0answers
23 views

Rheem RGDG unit turns on w/thermostat off, blower come on and inducer motor switches off and on

I've having a problem with my rheem model rgdg-10nbrjr The air conditioning works, turning it on at night it blows cold air and the house indeed gets cold. However the furnace unit itself ...
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2answers
14 views

Looped air conditioner condensate line not draining?

Using our split air conditioner for the first time, the wall unit started dripping water. Its condensate tube runs through the wall into an adjacent attic and then into the DWV vent stack. The tubing ...
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1answer
770 views

Need help adding a C wire for a wifi thermostat

With the increasing popularity of wifi thermostats I know this question has been asked many times, however I'll ask it again fr my specific situation. How do I add a "C" wire to my existing air ...

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