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

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114 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 ...
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1answer
28 views

What could be causing my Thermostat “R” wire to only be 8 VAC?

I am trying to install a Nest thermostat. It says Rh not powered. I checked with a meter and I get approx 8 VAC reading. What could be causing this? The furnace itself ain't pretty. Update: ...
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1answer
219 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?
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8 views

Replacing Flex Duct

I have few questions and need some advices. 1. can you tell me the size of my unit. It is Bryant, model 561CJX018000AEAA 2. The furnace is in crawl space and connects with 12" flex duct, 40 feet long, ...
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1answer
32 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 ...
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2answers
30 views

How do RH/RC/R and Y/W relate for HVAC?

I have the following notes for HVAC (that I've compiled from reading through here): Thermostat wiring: C low voltage power wire that brings power from heating/cooling equipment to thermostat ...
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1answer
41 views

Does it take long time to turn AC unit around?

I am wondering if it can take a full day of work to turn around AC unit like in this post . Must my new air conditioning unit be 3 feet from the wall (or positioned backward)?
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74 views

Must my new air conditioning unit be 3 feet from the wall (or positioned backward)?

My contractor installed this system yesterday, at my property: "Trane T4TTR6060C1000A RX16 5 TON XR16 A/C 16 SEER rating R410A". Everything is working fine. I just do not like aesthetically how he ...
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24 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 ...
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2answers
16 views

can I use AC top cover for Trane XR16

My contractor installed this system yesterday, at my property: "Trane T4TTR6060C1000A RX16 5 TON XR16 A/C 16 SEER rating R410A". ...
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3answers
43 views

How is the Air Conditioning wiring supposed to connect to my furnace?

My dog has chewed through my wires on my unit that turn on my fan at the ac unit. This is not the first time. Its always been an easy fix until now. He actuall pulled the wire from the unit and I ...
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1answer
168 views

Why isn't my Lennox G26Q3/4-100-6 furnace firing up?

I replaced the batteries, does not click when it calls for heat in the thermostat. fan blows but no heat. I took off inspection door, held the safety switch in, a blue light is blinking constantly, ...
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2answers
42 views

How to install small damper in a duct?

I need to install a Honeywell 10x10 damper into a 11x11 duct. Options that I came up with: build an adapter to reduce duct to 10x10 (alternatively I can use 12x12 damper and build adapter to ...
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1answer
45 views

Mounting a window air conditioner on top of a sliding horizontal window

I need to install a window air conditioner in my master bedroom. However, the only suitable window there is a horizontal sliding window. To complicate things more, I need to place it on top, since my ...
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2answers
50 views

reclaiming exhaust from 'on demand water heater'

Is there some way to recover the heat which is lost through the exhaust system from a 'on demand water heater' ?
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1answer
24 views

What is 3" (750Pa) wg class?

According to Sheet Metal & Air Conditioning Contractors’ National Association (SMACNA) - leakage test manual, It is not recommended that duct system constructed to 3" (750Pa) wg class or lower be ...
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1answer
253 views

Fan coil wiring problem with new thermostat

I'm trying to upgrade to a new line voltage thermostat. The new thermostat has many more connections, including three fan speeds. My current system has a manual fan switch on the wall so all I need ...
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2answers
39 views

Can I replace my furnace's high limit switch with a comparable third-party part?

I have an older Lennox furnace. The high limit switch (#60T15,130F) has gone bad. I haven't been able to find on-line this part number with the exact temp limit specs, and Lennox no longer carries ...
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2answers
92 views

HVAC System Just Installed Yesterday and AC condenser outside is blowing cold ir

HI my just installed ac condenser is blowing cold air out side . when I put my hand over it and move it around most of the air is hot but a portion of it is cold. Is this right ?
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1k views

Connected C-Wire to new Smart Thermostat and Furnace board and still no power

I need help. I've been surfing the internet and have had no luck finding answers to my situation so am hoping for some guidance. I've seen other questions here answered but none that suit my ...
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7 views

Need to clean permanent air filter

How do I access the permanent filter in a RUUD product ? The model number is either UBEA-14JO5SFFAI or RCGA-24A2GG14?
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1answer
305 views

Why won't my thermostat control the HVAC anymore after trying to switch thermostats?

I bought a new Nest thermostat which is supposed to be compatible but needs a professional installation (advice that should have been heeded by non-professional electrician me). This is to replace an ...
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2answers
59 views

Aprilaire 700 humidifier not working properly

The fan does not seem to be running. How can I determine what the problem is? I'm not sure if it's the fan, solenoid or the computer board.
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3answers
39 views

Compressor/fan stays off when cooling turned on

Before I begin, I would like to request "call a technician" suggestions to stay off. I do know a nice guy who can look it up for me, for a variety or reasons, one of which being my general history of ...
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1answer
23 views

Why doesn't AC equipment come with dehumidifier only option?

Every AC unit dehumidifies when cooling is on. I'm just wondering why dehumidification only is not an option, as is in standalone dehumidifiers? E.g. my basement stays pretty cool even in the summer ...
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1answer
101 views

Trane furnace pilot wont stay lit

I have a 1983 Trane gas furnace, Model BLU108E936B1, the pilot light went out, I could get it to relight but wont stay on> Changed the thermocouple, same results, Pilot light doesn't look right as I ...
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119 views

What could cause my Carrier furnace fan to sometimes stop running?

I have a Carrier system: FURNACE 58UVB080; AC 24APA530, CONTROLLER SYSTXCCUIDO1-B, approximately 7 years old. New filter, impeccable condition. I was initially told by the licensed installers that ...
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1answer
97 views

Hvac fan runs and shuts off in a cycle when in heat mode

I have a Heil hvac model. N44336336GKE100, The system works ok when in cool mode but when in heat mode the outside fan runs for 30 sec then shuts off for 20 sec and continually repeats the cycle. I ...
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1answer
1k views

Can I have a separate thermostat for a wood boiler?

I want to wire a separate thermostat for my outdoor wood boiler so that just the furnace fan will come on without the propane kicking on. This is a Coleman furnace. Is this possible and if so, how ...
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15k views

How can I calculate how large an airconditioner my house needs?

I know there are a lot of possible factors that go into determining the size of the air-conditioning system a house needs. Is there a standard way of calculating what is needed, or do A/C companies ...
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1answer
301 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 ...
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3answers
83 views

Will a 2-stage heat pump cool my upstairs on low stage?

I am currently upgrading my furnace from an oil furnace/AC combination to all heat pump. I am considering two stage vs single stage heat pumps. I understand that two-stage will supposedly give me ...
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2answers
422 views

How to fill / seal in-slab hvac ductwork?

My house is built on a slab. Within the slab are "channels" which act as ducts for the HVAC system. I assume it is partially lined with metal but based on photos from an HVAC-cleaner, it's hard to ...
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1answer
82 views

Best Way to Heat a Tri Level Home

I have a tri-level home, which is approximately 1600 sq.ft. Presently I have electric baseboard heat, with a pellet stove on the main level. I am looking to upgrade to a better, more centralized ...
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1answer
38 views

Replacement part for coal stove blower rheostat

I have an Alaskan coal stove and my blower rheostat broke this morning. I opened it up hoping to be able to fix the part instead of buying a whole new fan controller. Any motor controllers that I ...
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3answers
67 views

Duct Cleaning: Is Duct Sealer Necessary, Non-Toxic?

A professional contractor is cleaning AC Ducts, and after he scrubs the ducts, he wants to apply an acrylic duct sealer and de-odorizer. The container of the duct sealer has minimal lableing and does ...
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3answers
170 views

Why would Central AC, Fridge & Pool Pump All Fail Within 3 Days?

Could this be systemic? Something in the electrical system for instance? Or is it likely coincidental? HVAC repair says they can't find a leak but the freon is very low and was fully charged in ...
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1answer
31 views

Aprilaire 560 repair

My Aprilaire 560 humidifier will do a bang click many times before it turns the blower on. I replaced the solenoid valve with a new factory part and it still does the same thing. What next?
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1answer
126 views

Should I install the jumper on my new limit control?

I needed to replace fan and limit control (White-Rodgers, model 5D51-35), because the fan switch was broken (fan would constantly run) and heat would not stay on. I took a picture of the control, ...
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27 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 ...
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1answer
60 views

what is the cause whereby compressor working gets hot and stops, after cooled down picks up

My challenge was that, I have this refrigerator I'm working on and after awhile it is working and then the condenser become hot as the compressor discharges excess heat, which as time goes on ...
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2answers
34 views

Installing Honeywell Wifi on Ruud Furnace with G wire replacement

trying to install RTH9580. My thermostat has only 4 wires so I am trying to substitute the G wire instead of C wire. On the furnace I put a jumper between Y and G wires and moved G wire to C wire ...
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1answer
50 views

Water coming down PVC pipe from ceiling to furnace

Water comes down the PVC vent pipe to my furnace and leaks out at the elbow. Water seems to come even when the furnance is turned off. I had a furnance man come out. He said there is a leak at the ...
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1answer
739 views

How can I add a C-wire to a Venstar T5800 thermostat?

I am trying to replace my existing thermostat. My old thermostat has: Rh, W (coming from the heating unit). Rc, Y, G (coming from the AC unit). On the Venstar T5800, I can map as follows: Rh+Rc ...
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3k views

why does my heat pump wiring diagram show 7 wires going to the thermostat but the thermostat only says it needs 5?

Here is a link to the wiring diagram for my heat pump. The thermostat that I am planning on buying has the following terminals C, G, Y, O/B, RC, R, Aux, E, and L. The instructions say to jump the RC ...
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270 views

Correct Wiring for Furnace Blower Motor

After getting my furnace blower motor replaced, it now runs only in the following scenarios: 1. Mode "Cool" Fan "Auto" 2. Mode "Cool" Fan "On" 3. Mode "Heat" Fan "On" In other words it will not run ...
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44 views

Wiring for New Thermostat

I just bought new programmable z-wave thermostats (Honeywell TH8320ZW). I thought I had the wired correctly, but I woke up to a pretty chilly house this morning. The fan is working, but it seems to ...
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59 views

Swapping out Nest for Ecobee - c-wire issues

We are trying to replace our nest with an Ecobee (with remote sensor capability). We have an existing Nest thermostat which was installed on our boiler/radiator system last year. Back then, we had ...
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34 views

Should I get a single- or two-stage furnace for my three-floor brick home?

I just bought a house that has a furnace on its last legs. The house is 1941 masonry in Chicago with 3 floors: finished basement, first floor and a second floor that is a converted attic with vaulted ...
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147 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 ...