Questions tagged [ducts]

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Cut Floor joists for HVAC

I own an old home, circa 1919. In the 70's, when the new furnace was installed, they cut through the floor joists to run the air ducts. Awesome. So in direct correlation to those cut joists, are ...
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59 views

Air Filter size for (new to me) home HVAC

My wife and I just purchased / moved into a new house and I was going through each of the systems and found the HVAC filter, it was literally destroyed (it had filled with crap and crushed itself in ...
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Rough in bathroom exhaust

So, I have a pretty basic question that I can't really figure out for some reason. Is there a way to rough in bathroom exhaust fans before siding? In other words, there are trim kits for sconces, ...
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44 views

Flexible round duct - What to use

I'm re-routing some 10x3.25" duct through a bulkhead in my kitchen. Planning to change over to 6" round duct for a 4' segment that is relatively straight (no 90s). It was my intention to use non-...
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33 views

How to connect dryer duct to wall?

I just removed a stove and fan, and am left with this rectangular exit for the fan exhaust. I would like to hook up a dryer in place, and am wondering the best way to connect the round duct from the ...
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Should I insulate metal duct work in basement?

I have a balloon frame house with an unfinished basement. The air handler and furnace are in the basement too. Last fall, we had the duct work removed because it was wrapped in asbestos tape that ...
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217 views

Range hood vents into attic space

My house was built in 1976. I recently replaced the range hood and discovered that the piece of rectangular ducting that runs inside the cabinet is not connected to the outlet vent on the outside of ...
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Dryer vent through cinder block and then through yard - is this ok?

I've been researching how to vent my basement dryer, using galvanized steel ducts. There are lots of things on Google that show how to do this under a normal situation, but mine is unique, and I can't ...
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Air return proximity to furnance

We are refinishing our basement that wasn't original conditioned. New supplies and zoning were added by a contractor. We want to add an air return in the living space by tapping into the main return ...
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36 views

How do you remove and re-install Register Duct Boot?

Is it possible to remove and replace this register duct boot without screwing up the dry wall around it? Large Images: https://imgur.com/a/lh9HIt2
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51 views

How to calculate CFM/pressure needed to move water vapor through duct?

I made a cheap, high capacity humidifier from a mist maker, storage crate, and 120mm fan (the fan blows into the crate, which pushes the mist out). This 4" flex pipe works fine to exhaust the mist ...
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1answer
121 views

Move floor vent into the wall

Currently right by the toilet in my bath there is a heating register on the floor. I want to build a small wall at the same location and have the heat exit out of the base of that wall. Is there a ...
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33 views

Material for stud cavity cold air return

I'm totally aware of the arguments for and against stud cavity air returns so I don't need opinions on that, but I do need an idea of the best material for lining the outside of the stud cavity with. ...
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51 views

Dropped item in furnace duct

While trying to stop the ticking noise coning from my furnace ducts, I accidentally dropped a small piece of fire retardant foam (as you can see in the below photos) in one of the vertical furnace ...
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How do I stop the ticking noise coming from my furnace duct? [duplicate]

I've had some HVAC people here to look at the ticking noise coming from our furnace duct. One of them installed a brace on the piece in question. This seemed to make the ticking less frequent, ...
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24 views

Forced-air heater for old floor registers

I have an older home which used to be centrally heated by a furnace in the crawlspace, but has since been retrofitted with forced-air wall heaters: Some of the wall heaters are in inconvenient ...
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35 views

Best way to connect to short dryer duct inside wall

What is the best way to connect my dryer securely to this outgoing dryer vent? Should I find a small connector piece, place the crimped end inside the vent, and secure the inside of the joint with ...
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1answer
35 views

Crack in wall over heating duct

thanks in advance for any advice. We bought our 100-year-old house last summer, so this is our first winter in it. The walls are not insulated, so we can tell where the heat ducts run not only because ...
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Concerns with installing 4“ Dryer Booster Fan into 7” duct

Our new-to-us home was built in 1850, so there's been a lot of oddball things done to it's guts over time. One of these is the dryer vent duct work that looks to have been installed sometime in the ...
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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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215 views

How do I install flex duct to existing duct including registers

When my home was built in 2016 the HVAC runs from the furnace in the basement up through the house uses 7" R4.2 insulated flex duct. I am in the process of finishing my basement and I would like to ...
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54 views

How to seal joints in ductwork when tape is not an option

The duct-work in the basement for my forced air heating system has been modified at various points over its long history and as a result had quite a few leaks when I moved in recently. I used foil ...
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Why is this airduct twitching and making a noise?

I have an air duct in my basement. It leads from my furnace (I think?) to the outside world. However, as you can see from this video, it is "twitching". Every second or so it jerks slightly and ...
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Is 4“ Ducting Used for a 4” Bath Fan?

I'm interested in installing a bath fan and am currently planning ou the project. The fan specs (https://www.homedepot.com/p/Delta-Breez-GreenBuilder-Series-100-CFM-Wall-or-Ceiling-Bathroom-Exhaust-...
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68 views

Flexible duct behind dryer looks a little sketchy

So we just noticed that the air flow in our house is always bad when we run the dryer. Looking behind the unit, we found a foily looking mess of a flexible duct behind the dryer. It looks almost like ...
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Bought a home, return air vents on ceiling have R19 insulation shoved in them?

Checking filters and seeing what needs to be replaced, I opened the return air grate on the ceiling and what I find inside is a hunk of R19 insulation. Seems it should be some proper return air filter ...
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40 views

implications of small bottleneck in ductwork

I need to vent a sauna room (~200F) with an inlet duct that will open below the heater and an outlet that will open near the ceiling at the opposite side of the room. The ducts will be small (2"). ...
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31 views

use of conduit for ducts

I need 2" ducts in this room I'm building. Flexible ducts and conduit are about the same price. I have high heat requirements. Can I use conduit for ductwork? What are the pros / cons? Thanks
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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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3answers
62 views

Can I connect my two HVAC systems?

My house has two HVAC systems. One is in the attic and has supply and returns in the ceiling of the second floor. The other is in the basement with supply and returns at the floor of the first floor. ...
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18 views

Fan duct through cabinet

I have an auxillary ceiling fan in my kitchen and its duct needs to go 90° down the wall but the problem is I can't go around the corner. Can this go out the ceiling, go into the cabinet, and from ...
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1answer
82 views

Tape vs screw joining 4" duct

When joining 4" round duct, like for fart fans or dryers, is it sufficient to just use sealant and aluminum tape but no screw or should I be using screws also? It seems that the tape alone would be ...
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143 views

Can I remove the top plate at top of an interior NLB wall?

Is it safe to remove the top plate in one section of an interior non-load bearing wall between two studs space 16" apart? The reason I ask is because I need to run some ductwork to my cold air return ...
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33 views

How to minimize ceiling “backwash” of air circulation in an attic HVAC system

I'm remodeling and placing a new HVAC unit in the attic. The dining room is central on the house, adjoined by the living room, kitchen, service bathroom, and (directly or via a hall) all three ...
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373 views

How can I fix this furnace filter slot to prevent filters bending?

I noticed a problem with my furnace filter. In the vertical slot where it gets installed, there is a channel along the bottom but not along the top. As a result, the top corner of the filter ...
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45 views

Whole house dehumidifier- freestanding vs vented

I’m considering the purchase of a Dehumidifier for our basement, to avoid mustiness in the unfinished/unconditioned portion. I want a nicer quality HVAC-grade unit, both for energy-usage reasons and ...
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63 views

What type of crawlspace setup do I have?

New home owner here - I’m working on sealing the furnace ducts that run through our crawlspace. Previous owner used silver duct tape and not the proper mastic or UL approves aluminum tape. Long story ...
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Is a gravity or spring damper sufficient for a make up air vent?

I am planning on installing a make up air vent in my cold air return. I don't want to install an electric system that I have to wire to 3-4 different appliances. Is a gravity or spring loaded damper ...
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45 views

Will a make up air vent cause an issue in the winter?

I recently installed a gas range and I will soon be installing a 300cfm range hood. Since I primarily burn wood in the winter for heat and I don't want any back-drafting issues, I am planning on ...
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Is there any reason that plumbing can't be adjacent to a heating/cooling duct?

I'm installing a utility sink and the only place to put the plumbing (if it's going to be right under the sink) is either directly behind or infront of this vent... Is there any reason not to put it ...
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Round metal duct leaking water at crimped joint

Noticed a water leak stain in my ceiling in the drywall. Cut a hole and noticed water drops dripping from the joint of a metal round air duct. This duct leads to an external air vent on the side of my ...
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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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What is this device I found in my HVAC duct?

I was looking through my HVAC ducts with a camera and found this device attached to the side of a floor joist. It is about 2-3 feet from the air return vent. What is it?
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How can I reduce noise from tenants coming through my heating duct?

I live in an old house with a wood frame and forced air heating. My family lives upstairs and we rent out the bottom floor. My problem is that the sound from my tenant's bedroom travels directly into ...
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107 views

Is there some type of coating I can use to prevent condensate on my HVAC ducts?

I'm getting a lot of condensate on my HVAC ducts that run though my first floor (and HVAC blower) especially in July / August when humidity levels are outrageous (in NJ). The 1st floor space space is ...
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1answer
47 views

6" Ducting straight to in-wall rectangular ducting

I have a vent for the microwave-range that goes from an interior kitchen wall to the outside of the house. I need to re-locate this, but I can't move the exterior vent fixture. It currently comes in ...
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1answer
145 views

Can a motorized damper be installed inside existing ductwork?

My HVAC system consists of a fan, furnace, compressor-driven AC, and evaporative cooler. The problem is that there is a large air volume used only by the evaporative cooler that is generating a lot of ...
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Is my plan for moving return duct a few inches ok?

Below is my ac unit and the return duct that connects to the blower. I currently slide my 1-inch filter under that pvc pipe that's inside the furnace. PVC is in the way and there is no L-shape latch ...
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How to Sync Booster Fan with Furnace Fan

I own an old house. Some of the rooms in the house that are too far away from the furnace are not getting enough air, the airflow is too weak. I tried to close as many of the other ones as possible, ...
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Hood vent duct in floor - sealing it

I have an 8" duct that comes up through the kitchen floor (runs in subfloor between basement and 1st floor and vents outside) and through a kitchen cabinet bottom that will house a pop up vent. I can'...