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

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4
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1answer
405 views

Why won't the fan run independently of the air conditioner?

I have central air and heat, with a Nest thermostat. My system has Y, G, R, C and W wires coming out of it: which are wired into my Nest like so: In between, there is a splice where the C wire is ...
0
votes
1answer
160 views

Exhaust venting into air return?

In the condo (2 story semi-detached townhouse built in 2004) I rent, the main bathroom has an interesting vent system. When turned on, 2 fans are activated. One is a booster of some type and ...
1
vote
4answers
521 views

What could be wrong with my air conditioner?

My outside fan (compressor?) will not turn on. I have a week or two before the weather gets warm so thought I would try fixing it before I hire someone. Symptoms - I turn on the air. The blower ...
1
vote
3answers
381 views

I need a multiple-switch light switch which can't all be turned off at once

I have a 4 switch (I think it's called "4-gang"?) light switch on the wall. It's not connecting to lights though, but to AC vent doors. Now, these AC vents must never all be closed at once. Meaning, ...
1
vote
1answer
79 views

Plug HRV (Constructo 2.0 ES) into power bar?

Would there be any issues if I plugged this HRV into a power bar? I have this unit (says 200 watts of power) which is in the closet of the master bedroom and plugged directly into a wall socket. I ...
1
vote
3answers
574 views

How can I add ventilation to my basement office?

I have a finished basement with an office, guest bedroom and bathroom. All about 700 sq ft. I work 12+ hours in the office and really need to get some fresh air circulating by extracting stale air. ...
0
votes
1answer
115 views

What to look for in a new furnace

I've recently been told that my furnace, which is about 20 years old, is on it's last stretch and that I should consider replacing it now rather than waiting for it to fail - potentially at a very ...
0
votes
1answer
113 views

How can I add a relay to the manual control for my HVAC unit?

I have a self standing HVAC unit that has a control panel with manual buttons. There is no thermostat. Eventually my goal is to create a relay that can be controlled via IR/RF so I can install a Nest ...
3
votes
1answer
127 views

How do I install a bathroom exhaust system?

We are set to close on our house in about three weeks and one of the problems that the inspector noted was that the vent in the guest bath vents into the attic (never going outside) and the master ...
1
vote
0answers
542 views

How do I size a wall sleeve for a through-the-wall air conditioner?

We are shopping for a through-the-wall air conditioner. We do not currently have a hole in the wall with a sleeve in it. We are trying to figure out what sleeve to buy. The air conditioner we like ...
3
votes
1answer
95 views

Does code require the gas line to be replaced when replacing a furnace?

I replaced my 45 year old (still working) original furnace with an American Standard furnace about 5 1/2 years ago. Now I have a gas leak; the Nicor technician sealed a connection in the gas pipe ...
0
votes
1answer
279 views

Why isn't my thermostat working?

I have an old Lennox (gas heat only) thermostat. There are 3 wires coming from the wall. Black, yellow and a light blue color (could be a faded green or an old dirty white). The thermostat wouldn't ...
2
votes
2answers
372 views

Why does the pilot light on my Vermont Castings stove keep blowing out?

I bought a house with a sunroom heated by a Vermont Castings gas stove with a problem the HVAC/stove repair person hasn't solved by replacing the thermocouple, valve($$$) and taking apart and ...
3
votes
1answer
92 views

How do I provide proper fire protection in this situation?

HVAC guys are running a vertical duct (supply and return) from my basement to my 2nd floor attic. It will run adjacent to an exterior wall and will eventually be enclosed in a drywalled-in vertical ...
4
votes
1answer
488 views

Connection for C wire on Mastertrol Mark V zone control panel

I have spent hours searching the web for information on this 20+ year old zone control panel, which supports 3 zones of Heat and A/C. The thermostat I'm replacing (on Zone 3) connects to T4/T5/T6 as ...
0
votes
1answer
294 views

How can I get my thermostat C wire connected? [duplicate]

I have an older furnace, on the switch block I have Y,C.W,R and an unlabeled screw that connects to the shut off it looks like. I need to hook up a thermostat that needs the C wire. I have a spare ...
1
vote
2answers
140 views

Is it safe to install a heating duct register in the ceiling directly above a home entertainment center?

We're in the process of getting bids for central heating and one of the conundrums is where to position the registers. Due to the layout of our living room (and style preferences of my significant ...
2
votes
0answers
103 views

Does each zone in a two-zone heating system have its own pilot light?

I have two zone heating, in the basement and upstairs where we really live. The pilot light is lit downstairs, but the heat isn't working upstairs (the air is not getting hot). Is there also a pilot ...
3
votes
1answer
335 views

Where should carbon monoxide detector be located?

How many carbon monoxide detector is need in house and where it's more strategic to place it? Is it better to place it low close to the ground or high close to the ceiling?
1
vote
1answer
892 views

Can you terminate more than one common on the furnace C terminal?

TL;DR: Can you terminate more than one common on the furnace C terminal? Background: I've linked a diagram of how my non-programmable thermostat is currently hooked up. I want to replace it with a ...
10
votes
2answers
6k views

What does a Summer/Winter switch on furnace air ducts do?

On some of our furnace ducts, there is a switch/valve for Summer/Winter or S/W. What does changing this switch/lever accomplish? Can bad things happen if I forget to switch it? Bonus question: ...
0
votes
2answers
2k views

How can I use a separate transformer to provide a C wire to my thermostat?

I Purchased the Honeywell WiFi Prog Thermostat to replace my Round Digital Honeywell Thermostat. I have separate Heating and Cooling (Heating is a Weil McLain Boiler for Hot water baseboard and Hot ...
2
votes
0answers
55 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, ...
0
votes
0answers
172 views

Why isn't water running through our radiators?

We had a plumber in today to bleed our rads. He also changed the batteries on the thermostat and fiddled around with the boiler. Since he left the temperature has dropped dramatically and he's refused ...
1
vote
2answers
590 views

Why is my furnace blower coming on so early in the ignition process?

Alright, I installed a new furnace a few months ago and have begun to notice an issue with the blowers. When the furnace first starts up, the exhaust blower should turn on to expel gas, then the ...
1
vote
2answers
2k views

Why does the air flow heavily from my downstairs vents, but very weak from my upstairs vents?

I live in a two-story townhouse where the first floor is ground-level on a slab. On the first floor, all air vents are either on the ceiling or at the very tops of the walls. Upstairs, the vents are ...
4
votes
1answer
7k views

How can I prevent my HVAC condensate drain line from freezing?

Last night, my heat (forced air) suddenly stopped. Today, a plumber figured out that my heater is 90% efficient, produces lots of condensate, and the drain line had frozen. We went outside and saw ...
1
vote
2answers
1k views

What could be causing this leaky evaporator problem?

My apologizes if I do not know the correct terminology for some of the parts. I will try my best though. We have a Trane A/C system that is causing us a headache. It is causing water damage in our ...
1
vote
1answer
114 views

What does the low limit do, and where should it be set on an oil fired hot water furnace?

What does the low limit do, and where should it be set? My furnace has a honeywell triple aquastat relay and has a difference dial. Water temp is about 190 deg F. Also, water psi gauge is only ...
1
vote
1answer
136 views

Why won't my propane boiler's pilot stay lit after replacing the thermocouple?

The pilot on my propane boiler won't stay lit for more than 30 minutes even after replacing the thermocouple and outside gas valves. The inside gas valve was replaced two years ago. Service people ...
1
vote
0answers
352 views

What's causing my draft inducer to stay on?

I have a new, 3-year old, high-efficiency, gas furnace in my home. I recently realized that my draft inducer, which normally kicks on before the burners and before the main blower, is not stopping. ...
4
votes
3answers
3k views

What's causing the rumbling sound when my furnace kicks on?

I have a new, 3-year old, high-efficiency furnace in my home. Last year it started making a slight whining noise that was audible during the very first stage, before the blower motor started. No ...
2
votes
3answers
1k views

Does a whole house humidifier go on the intake or outlet of the furnace?

On what side of the furnace do I install the tank of the humidifier (the warm side or the return air side)?
1
vote
2answers
183 views

Is a PTHP a HVAC option for a super insulated structure?

Is a Packaged Terminal Heat Pump a good HVAC system for a structure that is super insulated or passively insulated assuming the unit is sized and fitted to meet the needs of the structure. There is ...
3
votes
2answers
847 views

Is voltage too high in C wire going to thermostat?

I've managed to add a C wire to my thermostat. I then decided to check the voltage between the R and C wires, and find that it read as 27.8 volts, not the 24 volts it was supposed to be. Could this ...
0
votes
1answer
290 views

How do I turn off the power to my programable thermostat?

I am installing a new programable thermostat. In trying to cut power to the old one I have tried a couple of things but not sure I have done enough to cut all power. One, I shut off the furnace ...
2
votes
2answers
4k views

Are there any ductless mini split systems that offer standard HVAC wiring controls?

Have been looking for in the US a ductless mini split heat pump system something like the Mitsubishi Electric Mr. Slim that uses a non proprietary wiring scheme for its wall mounted thermostats. ...
0
votes
1answer
226 views

How can I replace a 4-wire manual thermostat with a programmable thermostat?

I"m replacing a 4-wire manual baseboard thermostat with a programmable SBFT2W thermostat. After connecting the wires, there are two lead wires from the old stat that are still unconnected. They are ...
4
votes
2answers
2k views

Why does the pilot light go out when the furnace is running?

Every time the furnace fires up, it blows out the pilot light. Sometimes it will run a full cycle and blow out when it shuts down, and sometimes it will blow out about a minute into the cycle. We ...
2
votes
2answers
5k views

How can I prevent my house from smelling of smoke after having a fire in my fireplace?

We have a wood-burning fireplace in our family room. Fifteen feet from the fireplace is a large cold air return. When the fireplace is stoked, nice and cozy, everything is fantastic. When I shut it ...
1
vote
1answer
107 views

Is it possible to detect and repair a refrigerant leak in my HVAC system?

While replacing the blower motor in my HVAC's air handler, the technician mentioned that the refrigerant in the system was also low and that most likely there was a leak. Is the leak something that a ...
-3
votes
1answer
813 views

why won't my furnace turn off once it reaches the desired temperature

I have a moncrief furnace and replaced the thermostat but the furnace will not cut off once it reaches the desired temperature. What could be wrong?
4
votes
3answers
545 views

How can I redirect the discharge of my forced air vent?

An AC/heating register on our kitchen ceiling blows air directly toward a gas cooktop causing the flames to flicker. Adjusting the register doesn't seem to make a difference. I've looked into air ...
-1
votes
1answer
294 views

Why do I have a large PVC pipe venting warm air outside intermittently?

There is a large PVC pipe (3 actually) which vent air intermittently. I started noticing I could see steam rising over my deck in the morning and then I found that these pipes vent air at least a ...
1
vote
0answers
49 views

How can I add a common “C” wire to my thermostat? [duplicate]

Possible Duplicate: Options for adding ā€œCā€ wire to thermostat I recently bought the Honeywell THM5320R Wireless thermostat. After going to hook it up I found what many others have, it ...
4
votes
2answers
598 views

Do joints in adjustable duct elbows need to be taped?

Do the joints in adjustable duct elbows need to be taped as well once they're adjusted or are they considered air-tight?
3
votes
1answer
332 views

How do I support vertical runs of round ducting?

Supporting ducts horizontally seems pretty straight forward--just a loop of strapping underneath to support it. What about when the duct runs vertically? Do you use the same kind of strapping but ...
8
votes
1answer
238 views

Should I relocate the HVAC unit in my attic?

I have had a couple of estimates to replace our HVAC system and one contractor says he would relocate the system to a more central location in the attic. One says there is no need to relocate. There ...
1
vote
1answer
1k views

How to connect Nest in Europe

I found a question regarding the Nest thermostat here. But that is only a question "Will it work?". Thanks to that I know it WILL, the problem is...HOW. I know the wire naming conventions are ...
0
votes
0answers
83 views

I have no furnace, only electric blowing heaters. How do I get ventilation?

I have a 100 years old building with a store on the main floor. Since the building was built over 100 years old there is no ducting whatsoever. There is also no furnace. In the summer we just hook ...