Questions tagged [hvac]

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

435 questions with no upvoted or accepted answers
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1answer
111 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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128 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
64 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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830 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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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
82 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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2answers
135 views

TRANE XE70 GAS FURNACE - HSI only works once

My TRANE XE70 Gas Heater ..... HSI will glow hot once and heater works fine but then doesn't work anymore on the Thermostat cycle. I've replaced Flame Sensor and HSI Module. My White-Rodgers Control ...
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2k views

Daikin Mini Split Runs Constantly

We had a Daikin ductless system installed as a replacment for our old system that finally died. We have 4 total units inside the house, with 1 in each of the 3 upstairs bedrooms and a larger 18K BTU ...
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1answer
138 views

Old thermostat to Hive thermostat

My wife decided we needed a smart thermostat... which means I need to install said thermostat... Currently a Bryant Evolution series is mounted. She purchased the Hive with Hub when it was on sale. ...
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1answer
117 views

How can I prevent makeup air vents from exhausting conditioned air?

The utility room has two 8-10 inch ducts running to it from the exterior of the home. There are also three fireplaces in the home, and we have noticed that occasionally the house smells like smoke, ...
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59 views

Can I use an available wire as a C-wire by adding it to an unoccupied 24v terminal?

I want to add new thermostats in my home. Luckily, the wiring to my thermostat has an unused wire in the bundle for the required "C-Wire". It has R,G,Y,W, and an unused blue. The thermostat wiring ...
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2answers
108 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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77 views

Why is there a hole in return duct

There's a hole in return duct going under my house; why?
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47 views

CAR duct in same bay as electrical wire

I'm going to install a cold air return (CAR) duct through an interior wall that has some electrical running through it. The CAR duct will run vertically, but near the bottom third of the bay there is ...
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0answers
23 views

Can I place the MUA vent directly beneath the range?

In California, I'd like to upgrade my range hood and may require make up air. I've seen these installed in the toe kicks of kitchen cabinets. Would it be acceptable to install registers directly ...
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34 views

Heating zone only partially working for gas boiler

I did all of these things: Checked the pressure and temperature, which looked OK Attempted to "purge" the area. The zone (let's call it Zone 2), was purged by opening the valve on the return. I had ...
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102 views

No 24VAC between R and C on Rudd R801 Control Board

I’m replacing a older programmable thermostat with Ecobee 4 which is to control a Ruud R801 HVAC unit installed last year. I have access at the thermostat to a wire (orange) that goes to the C ...
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1answer
70 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
66 views

Heat pump always turns on with fan!

If I turn my fan on on my thermostats the heat pump turns on with heat or cool setting There is a jumper wired from green to w1(the heat pump) If I move the jumper to r (24v) and g and turn on the ...
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0answers
58 views

Dual energy controller 2AC02700701 runs heat pump with low fan only

I am running a central heat system that uses a heat pump as stage 1 and a gas furnace as stage 2. The thermostat is not directly connected to the furnace and heat pump motor, instead to goes through a ...
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0answers
777 views

Where should I connect my C wire on Goodman GMP075-3 Rev.B

I am trying to install an ecobee4 to replace a digital battery powered thermostat. I removed the existing thermostat and found that there was a spare blue wire that was wrapped around the others that ...
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790 views

How to wire a Taco zone valve controller with ecobee

I'm having an issue with wiring my Weil McLain gas boiler. It was wired up fine and working for a single zone. I added (2) 4 wire zone valves in. So I now have 2 zones, a Taco zone valve controller(...
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45 views

unique ? about venting tankless water header

I am installing a tankless water heater at the house. My question is unique because I can not find a reference anywhere in the code and the installation manual about where to place my exhaust vent. I ...
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1answer
950 views

Connecting Wood/Electric Furnace to Smart Thermostat

UPDATE: I spoke with an ecobee tech and they pointed me to an alternative solution. If I get an adapter called a "Fast-Stat Common Maker", all I need to do is figure out where to connect the C-Wire ...
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0answers
24 views

Upgrade Rooftop HVAC

I am planning a rooftop HVAC upgrade. My current HVAC frame (leg) has cracked one of the 2 x 6 roof rafters that I have repaired with wood glue and anchor screws, so it is good now, but it served as a ...
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94 views

How do I calculate fan size for a single room exhaust system to reach a desired cfm when restricted to specific duct size/route?

I am wanting to exhaust a sealed room (except for air intake and exhaust). The room is 512 ft3, and due to positioning, orientation, and existing construction, I am restricted to using 6" flexible ...
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2answers
83 views

HVAC Supply and Return Re-routing

We are planning a rehab of our first floor (2-story home). The furnace and air handlers are in the basement for the whole house. The supply and return for the 2nd floor run STRAIGHT up to the second ...
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356 views

Trane xv90 blower won't come on regardless of what the thermostat is set at

I have a trane xv90 and the blower won't come on. I'm getting about 20 green flashing lights and then 1 red which kinda overlaps the 21st green. What does it mean? I had turned on my trane air ...
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1answer
305 views

Which terminal should I connect it to for a “C” wire on an american standard AM4A0A30

I'm trying to connect a 3rd gen Nest thermostat. I have a 2 zoned heat and 1 zone AC. The zone with this thermostat has a boiler wired Rw, W1 and HVAC wired Rc, G, Y1. It's summer so I'm only using ...
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56 views

What heating mechanism do I have and how do I turn it off?

This is a bit embarrassing but I'm unable to figure out how my house is actually heated. I have some vents in the wall (just above the baseboard), which blow out hot air and are controlled by one ...
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263 views

Changing AC Fan Motor/Capacitor with No Luck

Issues with a central AC unit: Turned it on and heard a buzzing sound, but the fan didn't start. Started by looking at the dual capacitor. We happen to have two identical units, so I tried the ...
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5k views

Carrier Infinity System says “System Malfunction”

On this, the day temperatures reached 95, my AC stopped working. Here are the symptoms: The thermostat says "Infinity System - System Malfunction Call Technician". The condenser outside is spinning, ...
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2k views

Furnace Mainboard wiring with AC unit

I went to install a Nest on my upstairs HVAC unit. After installing the Nest I thought it was functioning properly. The next afternoon I came back to the house It was still hot, so looking into this ...
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2k views

How to understand the red and green blinking lights in Trane gas furnace?

My 8 year old Trane Model tuh2d120a9v5va furnace is not giving out heat, but the blower is on. The service people are all busy due to the recent storms. I imagine the ignition is not working. ...
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1answer
155 views

Which humidistat terminals should I use for my humidifier?

My Carrier furnace does not have a humidifier connection on the control panel. I have two wires from the humidistat. Do I use W-C or R-C connections for a normal operation?
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1k views

Furnace Condensate freezing on siding

I am helping a client with an issue related to the condensate line on their furnace. It is a high efficiently LP furnace installed in an attic with a condensate line that drains to the exterior. The ...
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31 views

Switch from 5“ HVAC Air Filter to 4” Air Filter?

Hi: I have 2 HVAC systems that use 20" x 24" x 5" air filters that are quite expensive to replace @ $60 each every 9 months. Would switching to 4" filters be ok assuming I change them slightly more ...
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0answers
45 views

furnace wont kick in

My furnace seems to work intermittently. overnight its seems to stop... i have checked the thermostat and it shows says it is heating. fan is on auto, but nothing coming out. when i turn heat to off, ...
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0answers
2k views

Running Airwave/Fan schedule with Nest (With Fresh air intake HVAC)

I am trying to make sure I am understanding the research/studies behind using just the fan to help reduce energy to cool/heat home. Nest has the option to set a schedule to run the fan in home to ...
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1answer
1k views

Air handler turns on even when set temp is reached

My HVAC is a heat pump system, the air handler inside is a Goodman aspf183016ea. The whole system/house is about 3 years old, and is all electric. I recently moved into the home and noticed that the ...
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0answers
4k views

Nest thermostat - electrical buzzing/humming noise

I have recently installed two nest thermostats (the black gen 3, and white model E). The system is gas radiator heat wired to the model E via the usual Rh and W wires, and Rh, Rc, Y, G, W wired to the ...
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2answers
447 views

Furnace Blower fan doesn't start

I have a keeprite high efficiency furnace that Was a part of my new house. It's 2016. The Honeywell thermostat is set at 23 deg C. This is what happens when the temperature is below the cut-off I ...
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3answers
806 views

Furnace turns on and lights without Inducer Motor Coming On

Without my brand new inducer motor coming on at all ever when power is turned on my gas furnace starts,igniter starts andlights pilot and then burners light and then big flame blowback like its ...
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1answer
620 views

Old AC and Gas Boiler wiring for new thermostat

I need help connecting a new 'C' wire for a Honeywell RTH6500WF thermostat. As you can see the heating is an old boilder with a simple pump to circulate the hot water to the baseboard radiators. The ...
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1answer
336 views

How should I jumper the transformer to use a thermostat with my heat pump?

I am hooking up an aftermarket blower motor on my Trane XL 1400 AC/heat pump. I have a black, blue, red & white wires coming out of the new motor. I am bypassing the circuit board so I am ...
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0answers
55 views

Heat pump shut down after 15-20 secs in cool mode

I have a York Stellar 2000 series Heat Pump model E1CS add-on system to a gas furnace. The heat pump had been working fine for a great many years. It now has problem in the cooling mode. When the ...
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2answers
129 views

Why doesn't my furnace fan run in cool mode?

Ok, the blower unit will run on heat and fan on. However when I switch to auto and cool the blower unit doesn't run. When I have the blower in the "on" position it will run until I switch the ...
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0answers
1k views

Putting a window air conditioner into an awning window

I bought a window air conditioner thinking that I could alter my awning window to accommodate it. I have since discovered that I can't remove the part of the window that swings out or alter it so that ...
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1answer
979 views

Can I run a C wire from Fan Relay

We've just moved into a new home with an heat only, oil, forced hot air furnace. The current thermostats are very old and we'd like to update them to something like a nest. The furnace is currently ...

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