Questions tagged [ducts]

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1answer
27 views

Type of insulation for flexible aluminum duct?

I’m replacing an undersized bathroom exhaust fan with a larger one that has a higher CFM. When switching the fan out, I want to add insulation to the flexible aluminum duct that goes from the fan to ...
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0answers
25 views

Sharing kitchen hood and kitchen ventilation through one duct

My kitchen currently does not have a kitchen hood, so I'm planning to install it. At the moment there is a ventilation duct, my idea is to connect the hood pipe to the ventilation pipe in the drop ...
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2answers
293 views

Is Complete Ductwork Required to Start the Condensor?

I'm in the middle of rebuilding my entire AC system. I've got one 14" return and two 8" supplies hooked up to the blower (on a 2 ton system). I plan to add much more, but for now I want to ...
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1answer
24 views

Use a concrete core drill (6") on plaster lath?

I'm installing a range hood vent through a double brick wall, so I need to rent a core drill and 6" core bit. Would it be possible/advisable to use the same bit to cut through the plaster and lath (...
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0answers
17 views

Range Hood Ductwork, ceiling to roof offset issues

I'm installing a new chimney style hood, with a 6" exhaust that vents through the ceiling. The fan I'm replacing has an 8" pipe, which vents out of the roof of the house. The issue that I'm having is ...
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2answers
43 views

How can I remove a mouse stuck in the air duct above a kitchen exhaust fan with built-in microwave?

Last night I heard noises in the cabinet above the microwave. There was nothing there but I heard squeaking and movement from the lower part of the metal air duct in the center of the cabinet. I am ...
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1answer
29 views

Flex-duct as a Trunk?

From my A/C supply plenum, I will have a trunk (approx 20ft straight run) with 3 branches coming off (each about 2 ft runs). This 20ft straight run would be perfect for a large flexible duct, and ...
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2answers
57 views

Side effects of wire mesh inside vent covers

I am considering tacking wire mesh (such as from a window screen) onto the inside of my indoor furnace/AC duct vents as well as the outdoor intake vents, for pest control. I know doing it inside the ...
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0answers
42 views

CFM ratings of inline duct fans far exceed the ratings for their intended duct sizes. What are we to make of this when designing a system?

My garage is 25×29' with 10' ceilings, so 7250 cf. I'm hoping to be able to turn over the air every 3 minutes or so, so aiming at using 2 fans rated at a total of 2400cfm. The fans I'd like to use ...
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0answers
11 views

Replacing flexible.duct work on AC unit

I purchased the correct size flexible duct for the air supply, but was unaware that the return side is 2 inches bigger. Since I am unable to purchase the bigger size until next week, is it safe to run ...
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1answer
106 views

Bathroom fan duct connection for maintainability

There are many questions on here about installing duct work for bathroom fans, but I have a more specific question. I am planning to use rigid duct for a new bathroom fan where there was none ...
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2answers
81 views

Do my HVAC ducts need to hang away from floor joists?

I have a basement that I would like to finish and install a drywall ceiling. And I would like that ceiling to hide the HVAC vents. However, the vents already just (by an inch or so) go over my head. ...
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0answers
15 views

Drafts coming from all floor Heating system ducts. Gaps between sheetmetal and floor have been sealed

I had my heating system, crawl space furnace and leaky poorly insulated sheet metal duct work, replaced a couple years ago with a 96% efficient system. The system was independently tested and ...
21
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5answers
9k views

Bathroom exhaust fan without duct

I just found out that our bathroom exhaust fan has no duct attached to it. Our current fan is Panasonic FV-08VQ2 (90 CFM, 4" duct diameter). The fan just blows the air to the inaccessible attic. There ...
2
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1answer
49 views

Can I reduce the floor register boot size in my old house?

I am replacing the subfloor in my turn of the century house. After ripping up the old floor, I realized that the floor register boots are huge compared to the size of the supply ducts. For example, ...
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2answers
59 views

Do I need ductwork for a through-wall exhaust fan?

We have a small wine fridge beneath our counter that was having temperature problems because there was no ventilation to allow the heat to exhaust. The other side of the wall behind the fridge is a ...
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2answers
33 views

Water Heater Exhaust - how to connect the 3 inch hood to four inch exhaust pipe

I'm working on this gas water heater with 3" hood almost attached to an elbow that reduces from a 4" exhaust flue. This was only attached by a lot of aluminum tape. The problem is that the ends of ...
2
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2answers
156 views

Sewage smell from kitchen sink area

(An update is below the pictures.) We just moved to our house in November and had to buy a new dishwasher. We had installers install it for us. A couple of months ago, we started noticing a bad odor ...
1
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1answer
129 views

How to accurately measure CFM with Digital Anemometer and Duct

We bought a digital anemometer to check the CFM of various fans we have on hand. My husband designed and 3D Printed this duct that securely mounts fans on to the anemometer for accurate readings, ...
1
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1answer
87 views

Re-purpose old water heater vent for bathroom exhaust fans

We just had our old gas water heater replaced with a tankless unit, so the vent for the old tank is now unused. I'd like to install exhaust fans in our 2 small bathrooms, and ideally use the old vent ...
1
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1answer
71 views

Can range hood venting ductwork be hidden behind crown molding?

Installing a range hood in older home going out the side wall. Am I correct in thinking that the duct-work can be hidden behind the crown molding? (is realistic?) Does the duct-work contain itself?...
4
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1answer
440 views

Venting Range Hood into Attic Space, Temporarily

My ductless recirculating range hood broke, and I have to install the replacement. I love to cook, so I'm installing a roof vent for a ducted hood. The range hood I bought has good filtering for ...
0
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2answers
56 views

What should I do with the airflow in a sealed off conditioned crawlspace

First and foremost thanks ahead of time for everyone's help :) I am in the process of finishing my basement and had some questions/concerns about "what to do with the air" in my crawlspace. ...
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2answers
52 views

What is the difference between these air ducts?

I'm fitting a portable AC into my workshop to take the edge off summer temperatures. For convenience, to make sure it works before bashing a hole in a brick wall, and to confirm it will help, I am ...
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0answers
81 views

Seal old ductboard from inside with duct mastic?

For the next few days, I have what appears to be an opportunity to easily and cheaply make a small improvement to the overall airtightness (or nearly complete lack thereof) of my house's 40 year old ...
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2answers
55 views

How large should a return HVAC duct be relative to the size of the supply?

I have a 4 ton American Standard electric forced air furnace (with no A/C - just heat) with a single speed blower motor, circa 2006. My supply main trunk is 12"x20". The return side of the system ...
1
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1answer
205 views

Can an 8" rigid duct be split into two 6“ flex ducts

I'm trying to finish an en-suite bed/bath that currently has a capped 8" rigid duct coming off the main trunk. What is the proper method to supply air to both the bedroom and bathroom? The bedroom is ...
1
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1answer
53 views

What is the standard way to secure flex duct in an attic?

I was in a house and noticed that flex duct (or what I think is flex duct) is being secured via a strap that's looped around the duct and then nailed to an attic truss (see picture below). Is this the ...
2
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1answer
174 views

How to extend ductwork a few feet due to soffit

I built a soffit around my ductwork in the basement. There was originally air vents coming out of the ductwork to heat/cool the basement. However, with the addition of the soffit, the vents are now ...
1
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1answer
96 views

Removing or modifying bridges between truss or joists to make way for ducting

I want to run ducting for a kitchen extractor through the ground-floor ceiling of a two story building in order to get it to an external wall. The ducting would be running in the same direction as the ...
1
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1answer
40 views

Using larger pipe for range hood

My new range hood calls for 5" pipe. I was planning to use a 5"/6" reducer to convert to 6" pipe for going through my attic to the roof. I know that using a smaller pipe than what is called for is ...
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0answers
101 views

Best way to retrofit a dyer vent duct in 2x4 interior wall

My washer and dryer are located on the second floor of a two floor townhouse (crawlspace foundation). It's basically a closet that fits the two machines only, with very limited space front to back ( ...
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1answer
25 views

How should I insulate garage ductwork when no gap exists between ductwork and ceiling?

I currently have uninsulated HVAC ductwork running the width of my garage. There's no gap between the ducts and the plaster ceiling above it. There's also very little clearance between the ducts and ...
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3answers
84 views

How to safely clean rust and prep on a section of HVAC ductwork before insulating

So I have a small section (about 1.5 ft) of non-insulated ductwork with some rust right above my HVAC blower/furnace in the basement. The rust seems to be caused by the water that sweats on that ...
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1answer
54 views

Furnace/HVAC issues in new build

Just had a couple of questions. I have been in new build townhouse for a month and noticed a couple of things but have been away several weeks so just dealing with it now. Some of this I am sure I am ...
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2answers
339 views

How can I attach/seal around an exhaust fan duct at the roof?

I am redoing the ducting from a kitchen exhaust fan to the roof cap. The old ducting was 6" and I'm increasing it to 8" to match the vent on the new exhaust fan. The current roof penetration is a 6....
1
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1answer
250 views

OK to cut double top plate to clear exhaust duct?

I am installing a exhaust fan duct in my 1st floor kitchen. I had planned to go under 2nd story joists/above kitchen cabinet, thru the wall. Unfortunately, the desired location on the wall would split-...
0
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1answer
74 views

What's a good way to minimize bends in a dryer transition duct?

I installed a new clothes dryer yesterday using the laminated foil transition duct the appliance store gave me. In order to get behind the dryer to access the duct, I have to pull the dryer out at ...
4
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2answers
1k views

How to make attic easier to traverse?

My attic is a maze of wires, air ducts and PVC water pipes. I went just one room over from the attic entrance and it took me a solid 30 minutes just to go there and back. Would it be unreasonable to ...
0
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1answer
69 views

Axial or centrifugal fan for short run out of kitchen?

I'm researching replacements for a broken extractor fan in my kitchen. It is wall mounted and runs through the wall straight outside, no long ducting involved. The current (broken) fan is the ...
0
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2answers
44 views

How to fix placement of over-stove exhaust

The microwave over my stove expired. I pulled it down, and discovered that the ductwork to attach the fan to the outside world was misplaced: it's about two inches to the right of where it should be. ...
2
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2answers
48 views

Ceiling vent right next to wall. Ideas for grille cover?

The typical size 10x4 won't work because the wall is right next to it on one side (see picture). I can buy a smaller size but then the question is where do I screw in the second hole. Any ideas?
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0answers
30 views

Using existing hot water vent for extraction

I have a room in the basement with equipment (computers) that gets really hot. There is an ac vent but the thermostat is nowhere near the room. Also in an alcove is the hot water heater behind a ...
2
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1answer
835 views

How can I duct through a new cabinet from a floor vent opening at the wall?

Got a window bench put in, but need a way to direct the air from the old baseboard vent register hole to out the front of the bench. NOt so sure a box store is going to have the proper vent duct parts ...
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0answers
41 views

dryer duct: connecting crimped end in dryer to crimped end in wall

A friend redid the in-wall duct for the dryer, leaving a crimped duct coming (slightly) out of the wall. Our dryer has a crimped duct emerging as well. Friend, who has left the area, was probably ...
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0answers
14 views

water in insulation boards - best method to dry out

I have a horizontal flow brand-new HVAC unit, with a 1" thick insulation board plenum which has had some water ingestion on the bottom panel. The unit is in the attic. I'm quite confident the water ...
1
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1answer
69 views

HVAC Air Blowback

Furnace/Blower: Rheem R92PA0851521MSA Dual Zone System (Honeywell TrueZONE HZ311) - Honeywell M847D1004 Actuators Age of system: less than 2 years old including ductwork Ive noticed that if Zone 1 ...
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0answers
43 views

Closing drywall to duct work

We are trying to convert some garage space into a gym, and one the we’re concerned about is all the gap space between the drywall and the ducting. We want to seal that off as much as possible for air ...
1
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1answer
65 views

How to re-purpose an exhaust fan using a 10x3.25 duct?

I'm currently remodeling my kitchen. Instead of a cooktop hood, I plan to re-use the existing ceiling exhaust fan. It looks to be about a 8" diameter fan that is inside a 10x3.25 duct that exhausts ...
1
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2answers
612 views

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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