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

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15 views

AC Unit does not receive 24 volts on outside unit

My outside unit does not turn on itself, but it does work. I just did a quick repair just thinking it was the capacitor and it was only 15 dollars for a new one so I changed that out and still had the ...
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3answers
73 views

Five Year Mystery - Unable to find source of burning smell from HVAC system

There is a burning smell that wafts out of the vents of my 15-year old, 3-level townhouse (top level is a full unfinished attic with no HVAC). The bottom level of the townhouse is the main level ...
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1answer
10 views

HVAC compressor turns on when calling for fan only

I just moved into a new apartment with HVAC, and I'm looking to control the thermostat with a few Phidgets (I had already invested in that ecosystem, so I just needed a couple of relays). Anyway, ...
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1answer
267 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
44 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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0answers
32 views

Removing stuck “through the wall” air conditioners

I have two through wall air conditioner units that cannot be removed. These were installed within sleeves in the 1970s and have been sitting there ever since. One budges a little and the other, not at ...
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2answers
99 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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0answers
12 views

I would like to view answers and answer questions [migrated]

I would like to view answers (and answer) questions. I have years of experience in construction and HVAC, but little experience with computers. How can I get a few reputation points to do above?
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1answer
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 ...
2
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1answer
323 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
60 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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1answer
11 views

Fan runs when in “on” mode, but not when in “auto” mode while in “cool” setting

I have a Rheem RHPL-HM2421JC air handler, a Rheem 1.5 ton heat pump condensing unit, and a comfort control thermostat. The heat and fan worked well over winter. I can also turn the fan mode to "on" ...
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1answer
104 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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0answers
23 views

Yellow wire connected to C terminal, blue wire connected to Y terminal at furnace

I'm trying to install a new smart thermostat the requires a C wire. My old thermostat operated on batteries. The pre-existing wiring system of the old thermostat looked normal (ie. red wire to Rc, ...
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1answer
25 views

How do I wire my old 3/4hp 115-120v 50-60Hz HVAC motor to make an exhaust fan?

My old HVAC blower motor has the following wires and I would like to know how to wire them to a typical 110v plug for use as a garage exhaust fan. yellow (N) black (L) yellow/green (ground) black (M1) ...
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0answers
19 views

A/C Insulation on Evaporator Unit [closed]

The issue is however the Lining of the A/C Unit inside was found to be Glued to the Sides and bottom which I believe is called the "Pan". The Apartment had an issue of Mold as the A/C was 3 ton unit ...
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1answer
104 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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0answers
12 views

Why does my hvac minisplit freeze up?

What would cause a mini split to freeze up? The Freon level is correct and the air flow is good. This is a multi head system (2) one is working properly the other is freezing up.
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0answers
12 views

Can I increase the “constant on” speed of my air handler?

I have an American Standard TWE049E13CB air handler with a variable speed blower. The manual has a chart to adjust the dip switches for fan speeds for cooling, heating, fan off delay, and auxilary ...
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1answer
329 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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0answers
15 views

Outside 4 ton AC unit bad [on hold]

I purchased an outside AC unit, 4 ton, from a person on Craigslist a couple of months ago. I was given a written one year warranty by the seller. When I had it installed yesterday we found that the ...
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2answers
456 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
27 views

Run HVAC fan throughout the day for comfort

At my old house, we replaced the HVAC with a high efficiency unit that came with a thermostat that would blow, say, 50% to 70% of the time for air movement to increase comfort level. I'm not sure but ...
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0answers
41 views

How do I connect a honeywell wifi thermostat with no C wire at the furnace?

I purchased a Trane XV90 furnace in 2001 & I'm upgrading the thermostat to a Wi-Fi model. This thermostat needs a wire labeled C from the furnace & of the 4 wires coming from the furnace none ...
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1answer
96 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
35 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
55 views

Central Air Unit not Sending Enough Power to Thermostat

Right now I don't have specifics on my central air unit (make, model, etc) but hopefully the info I provide will help. I have a Second Generation (and Third Generation) Nest Thermostat hooked up to ...
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1answer
38 views

What is the difference between the coolness of different wall types in hot weather

Given a 30cmx30cm concrete beam and pier structure, with infill, and year-round (equatorial) daily temperatures of around 25C-33C, with around 80% humidity. What is the difference between these ...
13
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5answers
11k views

Ethernet cable instead of Thermostat wire?

I need to pull new wire from my furnace to my thermostat and was wondering if there would be any problems in using an Ethernet cable instead of standard thermostat wiring. The reason being is I have ...
3
votes
3answers
3k views

How can I heat up my apartment to kill bedbugs in Southeast Asia?

I have a bedbug problem in my apartment and I want to fix it myself with heat. (I do not want chemicals sprayed around.) Apparently, getting a room to 140 degrees for two hours is sufficient to kill ...
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0answers
23 views

Improving air flow using supply and return exhaust fan with split type air condition

I have slight issue with uneven temperatures between two rooms. Say we have two rooms, Room 1 (cold room with AC) and Room 2( without AC, hotter room). Room 2 is ventilated by Room 1 AC by opening ...
3
votes
1answer
132 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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votes
5answers
2k views

Do I need to level the outdoor AC cooling unit?

I've read somewhere that the outdoor AC unit needs to be leveled. My outdoor unit is a bit slanted due to the floor not being completely flat (pic below). However, I don't see any obvious structural ...
3
votes
2answers
28 views

Window unit lets in lots of outdoor noise. How to insulate?

I just moved to NYC and I have a window unit like this: The foldable frame around either side lets in a considerable amount of outside noise; it's just as if the window was open. In fact, I'd swear ...
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1answer
61 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
38 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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9answers
11k views

Would putting a sprinkler on my roof help cool my home?

Anyone ever put a sprinkler on your roof to help out your A/C on unusually hot days? Just wondering if it helps.
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0answers
6 views

furnace blower not working off of thermastat

I replaced mother board of furnace and the fan blower turns on but my wires from thermastat are not plugged in.black wire on Hi red on low white on com if unplug hi it does not turn on
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0answers
10 views

Safe to install a 3 Ton HVAC with 8" ducting

I currently have a pretty old 2.5 ton HVAC installed and it broke down recently so I need to replace it. I've had a couple companies come out and give me bids and they both insist that I need to ...
0
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1answer
744 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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1answer
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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1answer
53 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 ...
0
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1answer
351 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 ...
0
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1answer
158 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 ...
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1answer
38 views

electric heater keeps needing to be reset by turning fan on and off atleast every 1-2 days

My electric furnace is about 23 years old, it quits working but does not trip a breaker. It feels warm to hot at furnace and just kind of clicks occasionaly when I turn thermostat up to 90 to try and ...
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1answer
152 views

Can't get my AC to turn on at all

Recently our AC stopped working. The thermostat is working properly, but the unit just started blowing hot air. I've never worked on a AC before, but I was trying to save some money. Anyway started ...
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1answer
36 views

AC Condenser Fan Won't Spin and Overheats But Can Be Kickstarted

Symptoms: AC kicks on, but blows warm air Found issues: AC kicks on and AC condenser appears to turn on (makes noise), but the fan won't spin. A few seconds later, the condenser fan motor overheats ...
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1answer
88 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 ...
0
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1answer
38 views

Oil furnace fan won't shut off when “heat” plug is connected to control board

I was changing my thermostat and I attempted to make the swap live without turning power off. When I connected new thermostat, the fan kept running. Ruled out bad thermostat and wire short by ...