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

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3answers
6k views

How can I improve second floor HVAC performance?

I have a forced air heating and air conditioning system that performs poorly on the second floor: It is way too warm in the summer and a little too cold in the winter. I live in a 1920s masonry row ...
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3answers
5k views

Should I be concerned about fridge/freezer airflow?

We just recently had the following counter/cabinet system put into our basement family room. After everything was done, I started to get concerned about airflow. The enclosure was built in such a ...
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2answers
3k views

What is the maximum angle I can set my window AC unit?

We know an AC unit must be angled to allow runoff. But what is the maximum angle and what is the issue with having to large of an angle? I've seen people say the angle is "5/16" or "3/16" but this is ...
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2answers
2k views

Can an HRV replace the air exhausted by a range hood?

I'm in the process of buying a 1950s ranch house. It doesn't have the greatest insulation, so I'm planning to do some improvements over the first few years to tighten things up. I'll certainly do the ...
5
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1answer
140 views

Does lack of zone control delay hurt heat pump?

I had a new HVAC single heat-pump system installed with dual zone controls: 2 thermostats and 2 dampers for separate zones. The system works, but the zone control board does not have any time ...
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4answers
150 views

What concerns should I have installing a HVAC unit and ducts in a home that's never had it?

We're looking at a house in southern Alabama that has no central heating and air. I would like to put one in. The house was built in 1950. What should I be considering about the installation?
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1answer
1k views

two condensate drains?

we just had a new AC system installed in my florida house. the unit is in the garage, and the air handler is vertical with the evaporator on top. the unit he removed had 2 condensate lines: one that ...
5
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1answer
1k views

Do I need to increase my HVAC trunk line size?

I'm thinking of finishing my basement. I currently have a main trunk coming off my furnace that measures 20" wide by 6" tall. I'm trying to future proof my home in the event my current furnace can't ...
5
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1answer
346 views

Is it possible to recover waste heat from a boiler?

I did a google search and came back with industrial products, but no residential prosucts. I have a System 2000 boiler and hot water tank. When the furnace is firing, the temp of the exhaust through ...
5
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1answer
910 views

Is there a wireless thermostat that will make relocating easier?

I've got a single zone which covers all three upstairs bedrooms in my home and the thermostat is located in the master bedroom. We prefer it to be somewhat cooler at night, but the baby in the ...
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7answers
9k 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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3answers
2k views

Advice for replacement/repair of an HVAC with a cracked heat exchanger?

My townhouse has a downflow 1994 Rheem 2.5 ton HVAC unit on its roof (combines both A/C and heat). We have had two issues with the unit and have been in the townhouse for a little under two years. In ...
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2answers
4k views

Can I run heating duct work through the attic?

Problem... (in Buffalo NY) We just about finished remodeling our master bedroom. Everything insulated, drywalled and we're living in it. Now that the winter is upon us, we're already finding this ...
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2answers
212 views

Who do I hire to design my home HVAC system?

Preface I need to buy a new HVAC system for my 1930s home. I currently have forced air duct system. My gas furnace was installed in 1985 and is rusting out, and I'm not sure about the air ...
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3answers
2k views

Is there a trick to getting round HVAC duct pieces to fit together

I have been doing some basic HVAC duct work as part of a remodeling project and I can never get the pieces to fit together without massive amounts of elbow grease and mangling the ends. Is there some ...
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2answers
3k views

What are these two pipes coming out of the house?

I am trying to figure out the purpose of a couple of pipes that are currently coming out of the house. First, a couple of notes: One-story house. HVAC system is in the attic. It is winter here. ...
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1answer
5k views

Is flexible gas pipe safe to use for main or long runs?

The house we purchased is a "tear-down". A builder bought the older structure, partially tore it down and built a bigger house on the old footprint. A lot of the original gas piping is still in the ...
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3answers
2k views

Is an interior laundry room without an HVAC vent a code violation?

Currently looking at a home which has a nice 2nd floor laundry. Vented dryer, nice rack for hanging clothes, etc. However, it's in the center of the home and does not contain an HVAC (central air) ...
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3answers
126 views

Geothermal Resources

I am very interested in learning more about Geothermal solutions for my house. What are the best resources for learning about and planning a Geothermal systems for a residential house? Also, does ...
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3answers
4k views

Why is my gas furnace vibrating when blowing hot air but not when blowing cold air?

I have a gas furnace. I recently replaced a bad blower motor. At that time I also cleaned out the blower housing and squirrel cage. The AC runs fine with no vibrations or any symptoms of an off ...
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2answers
1k 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?
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2answers
2k views

Are there high flow floor heat registers available?

The weather has been pretty warm lately so we've been running our A/C. I noticed that it didn't seem like much air was coming out of the registers, so I checked to make sure the blades/louvers were ...
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2answers
116 views

DIYer to skilled tradesperson

What is the process a DIYer has to go through to become a skilled tradesperson? Are the only options apprenticeships, or are there other paths to follow to learn a trade/become licensed? What type ...
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2answers
90 views

Resources for designing new HVAC [closed]

Our house is a bungalow with full basement and is currently heated via electrical baseboard heaters in every room. I'm converting this to a central air system heated by a gas furnace, and possibly ...
4
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2answers
6k views

Should my thermostat's blue wire be going to W2?

I've recently moved into my first house and am looking to replace the existing basic thermostat in the home. Here is a picture of how I found it wired: Researching the wires, I've read that ...
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1answer
3k views

What would cause my furnace to only work with the filter removed?

My Carrier furnace works fine without the air filter in place on the return. With the filter in place it works for a while and then stops with a complaint about "limit, or flame rollout is open" ...
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4answers
11k views

Can I using a 3-phase connection to power 1-phase AC unit?

I have preparation for an AC connection with 3-phase 220V 3X16A breaker. I want to install a 220V 1-phase unit, which also needs a 16A breaker. The physical connection has screw-on terminals, so there ...
4
votes
2answers
61 views

Solution for fiberglass ducts that have collapsed in basement?

I have two furnaces in my house, one for the basement and one for the rest of the house. I noticed that while using the basement furnace this winter that no air was coming out of any of the basement ...
4
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2answers
2k views

How do I improve heating in back room of house?

The back room of my house is quite warm in the summer. The room is on the north side of the house (Alabama, USA), so the outside walls don't get direct sun exposure. The attic insulation is a little ...
4
votes
3answers
9k 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 ...
4
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1answer
2k views

Can I reroute this air duct?

I'm quite new to dealing with HVAC duct-work. We would like to install a suspended ceiling in this room. Since the finished ceiling will be higher than this duct-work, we're going to build drywall ...
4
votes
2answers
15k views

Workarounds for single-zone HVAC? Second thermostat? Adjust vents?

I have a two story brick home built in 1970 with a relatively new HVAC system blowing through original ductwork. In the summer its too hot upstairs and too cold downstairs. I know that the full ...
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2answers
785 views

ductless AC split systems?

Does anyone have the ductless split AC systems offered by Mitsubishi, etc.? Is installing them a DIY job? Can you share your comments about them, in general? Edit: Inspired by DA01 comment, I'd ...
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1answer
1k views

What's wrong with my thermostat (fan / limit control)?

I previously asked about wiring the White-Rodgers fan/limit control on my wood stove. It's now wired and the wood stove is fired up. I ran the fan wires to the fan (hot) and I capped the limit ...
4
votes
1answer
425 views

How can I determine if my HVAC system has features which are not currently wired to my thermostat?

I recently upgraded to a Nest Thermostat. This new thermostat supports many more terminals and features than my previous thermostat. My old thermostat had the basic terminals; G,R,C,Y, and W. I am ...
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7answers
43k views

Should I insulate air conditioner coolant pipes?

I recently replaced some rotted insulation on the coolant pipe that runs out of my AC unit and into the evaporator in my house. When cleaning inside the actual AC unit itself I noticed that the ...
4
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1answer
1k 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 ...
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2answers
1k 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 ...
4
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1answer
2k 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?
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2answers
927 views

What are effective ways to frame a return air duct?

Consider an in-floor return air duct that is 32" x 22". A standard air filter that closest fits the register is 30" x 20". What materials should I use to frame the duct so it will snugly hold the ...
4
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1answer
2k views

Adding AC to forced air system

We have an old house that happens to have forced air. Unfortunately, according to an HVAC tech it looks like there aren't sufficient return vents to add a compressor to our furnace. I guess I'm ...
4
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2answers
102 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 ...
4
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4answers
7k views

Why would my Goodman gas furnace start but not stay on for more than 2-3 minutes?

I've got a problem with my 15 year old Goodman furnace. It starts w/o problem, inductor begins working, hot surface ignitor lights up and ignites the gas. Then the main blower starts working and the ...
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3answers
4k views

How effective is a heat pump for AC and a heat pump/furnace for heating in New England?

We currently have a central AC unit and oil furnace. The AC is broken and the furnace is old, so we are thinking of replacing both sometime in the next year. We are considering replacing the AC with ...
4
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3answers
1k 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 ...
4
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1answer
813 views

How can I protect A/C condenser wires?

I bought a replacement condenser fan motor for my outdoor A/C unit. The old unit was CW direction only. This one is CW/CCW and has 4 wires stick out of the side that change direction depending on how ...
4
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1answer
121 views

Is it possible to install a whole house humidifier away from the furnace?

My building is essentially a single extremely large room. It's a 25'W x 45'L x 20' H concrete box, with an open mezzanine over the back 1/3 of the box. The HVAC system is gas-fired forced air, ...
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4answers
1k views

Can I reduce static pressure in one room by adding a vent to an adjoining room?

Our return vent for our hvac is right outside the master bedroom. The master bedroom gets very little airflow with the door shut. It was recommended that we add secondary return duct in the master ...
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2answers
1k views

How well do whole house humidifiers work?

We are moving to an area where it gets cold and snows in the winter. We come from a desert area where it is never very cold except for the dead of winter, and where we use the heater very seldom. We ...
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1answer
3k views

How should one size ductwork for a new air return duct?

I recently had a contractor build a wall which split one room into two. The new room is an office with two computers, and four monitors. It gets very, very hot, until the air conditioning turns on, ...