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55 votes

Gas clothes dryer is venting into the crawl space

I don't like the "OMG" abbreviation and seldom use it, but in this case OMG! It would have been bad enough to vent an electric dryer into a crawl (lint, moisture, fire danger), but to vent a gas ...
George Anderson's user avatar
30 votes
Accepted

Is it safe to use Category 1 80,000BTU furnace with 2 inch PVC exhaust?

HELL NO Whichever joker is installing an 80% furnace with a PVC pipe for the exhaust needs their license revoked pronto, because that's a patent CO hazard. Non-condensing appliances operate at flue ...
ThreePhaseEel's user avatar
24 votes

Why do gas water heater exhausts have an air gap before the chimney?

The actual amount of combustion air - i.e., air flowing past the burner to provide oxygen and leave with less oxygen but more CO2 and possibly other combustion byproducts - is very little. The gap ...
manassehkatz-Moving 2 Codidact's user avatar
22 votes
Accepted

Using old vent pipe as TV antenna

There is a LOT that goes into making an antenna work properly. That's why the old-school TV antenna has so many little rods sticking out the sides - they have to be certain fractions of the wavelength ...
FreeMan's user avatar
  • 47.4k
16 votes

Do you to block a unwanted 4 inch hole or reuse it for something else?

Yes, you can cover it up with plywood. However: was made by builder for no reason No, it was for a reason. If it was for no reason, they would have likely just covered it with regular siding. When ...
manassehkatz-Moving 2 Codidact's user avatar
16 votes

My new AC is under performing and guzzling too much juice, can anyone help?

I absolutely applaud your exploration of new HVAC tech. Right now, the industry (Carrier, Lennox etc.) are very much like the auto industry in 1980. They're still shoveling the same old products even ...
Harper - Reinstate Monica's user avatar
13 votes
Accepted

Why do gas water heater exhausts have an air gap before the chimney?

This is a draft diverter. If the heater was connected directly to the chimney, the hot flue gas would rise, creating draft in the heater. While that is a good thing, the amount of draft would depend ...
Level River St's user avatar
12 votes

Why do gas water heater exhausts have an air gap before the chimney?

manassehkatz covered a lot, but the simple answer is constant air flow The draft will change in the chimney as exhaust vents towards it – especially when going from cold air to hot. A draft hood is ...
Machavity's user avatar
  • 25.3k
12 votes

Gas clothes dryer is venting into the crawl space

As George Anderson's answer says, this is extremely unsafe and must be fixed. But don't try to fix it by making expensive modifications to your home. Gas and electric dryers are inefficient anyway, ...
R.. GitHub STOP HELPING ICE's user avatar
9 votes

Can I vent a bathroom through the soffit if I use a product designed for it?

In the past I was a big fan of soffit vents. I figured if you used quality vents with a good back-draft damper, and sealed and insulated the duct well, it was a great way to vent bathrooms. There are ...
Dan A's user avatar
  • 101
8 votes
Accepted

Bathroom Vent Fan Upgrade

You can install a reducer, but you'll cut your flow volume by an equal proportion: 28.3in2 - 7.1in2 = 21.2in2 (an area reduction of 75% when going from 6" to 3" duct) This will negate a significant ...
isherwood's user avatar
  • 140k
8 votes

What kind of putty should be used for sealing rim joist exhaust vent holes?

So the water heater installers had a beaver or squirrel on the crew to gnaw a hole, rather than using hole-saws like competent workers? Ugh. I'd wrap that tightly in a scrap of plastic (housewrap or ...
Ecnerwal's user avatar
  • 220k
7 votes

Is it safe to use Category 1 80,000BTU furnace with 2 inch PVC exhaust?

Are you sure that contractor is not secretly a hitman? I give him props for creativity, that's for sure! On a serious note, furnaces with efficiency of less than 90% must be vented via metal pipe ...
MonkeyZeus's user avatar
  • 16.7k
6 votes
Accepted

Direct stove/kitchen exhaust into kitchen sink drain

No. Your traps need to have water in them to prevent sewer gasses from getting into your home. If your vent "seal" was strong enough, you could "clear" the trap allowing gas into the home. Flammable, ...
noybman's user avatar
  • 2,025
6 votes
Accepted

What kind of putty should be used for sealing rim joist exhaust vent holes?

That kind of putty is called “duct seal” and you can get it pretty much any hardware store, big box hardware stores, electrical supply shops, etc. it will work fine.
RibaldEddie's user avatar
  • 2,420
6 votes

Can my Furnace and Water Heater share an exhaust?

If the appliance instructions say they can share an exhaust, then they can share. (Hint: The instructions won't allow it. The high-efficiency, also called "condensing" appliances, pretty ...
Greg Hill's user avatar
  • 31.3k
6 votes

Electrician says existing switches won't work to Install Broan CST80SLW vent fan - correct or not?

Your electrician is most likely wrong. It sounds like your original setup was like this: Power comes into your switch box and connects to two separate switches (one for the light and one for the fan) ...
BEN's user avatar
  • 61
5 votes

Bathroom Vent Fan Upgrade

Let's back up here for just a second and note something You almost certainly don't need a 150CFM fan. So your original fan was a stock 50CFM (probably NuTone or one of its predecessors) that's a 4-...
Machavity's user avatar
  • 25.3k
5 votes
Accepted

Multiple concentric vent kits

You're fine IFGC 503.8 is the governing Code passage here, and it sets no minimum spacing for direct-vent terminations from each other, just from features that could draw combustion gasses into room ...
ThreePhaseEel's user avatar
5 votes

Using old vent pipe as TV antenna

If you want to try this and see what happens, all you need to do is take the end of your coax and touch the center part of the connector to the pipe, while making sure the outer sleeve of the ...
Kevin Reid's user avatar
  • 4,054
5 votes
Accepted

What is this metal object inside the hot water tank vent?

It appears to be a flue baffle. Many gas-fired water heaters have these inside the flue way to slow the movement of the flue gases (ie the heat produce by the burner) and improve the transfer of heat ...
Greg Hill's user avatar
  • 31.3k
4 votes

Can I vent a bathroom through the soffit if I use a product designed for it?

OK--the UCC code specifically says: • Section 1501.1 Outdoor discharge – Air removed by every mechanical exhaust system shall be discharged to the outdoors • Air shall not be exhausted into an ...
Dave's user avatar
  • 41
4 votes
Accepted

Connect 4" Dryer Vent Duct to 4" Exhaust Pipe

At the least, buy this. The reason it is the least, is lint will still get trapped in the edge that goes into the flexible part. Joints should be placed so the moving air flows over the joint, not ...
Jack's user avatar
  • 35.7k
4 votes
Accepted

What type of duct should I use for a clothes dryer exhaust?

Assuming the 16' distance, plus any other lengths and elbows falls within the manufacturer's guidelines, I would use sheet metal round ducts, usually 4" diameter. If you mount them so the ...
SteveSh's user avatar
  • 6,912
4 votes
Accepted

Are exhaust fans inter-connected in a 3 stories condo?

Many building like that were built without actual duct work but used the space between the joists, ceilings and floors. Running your fan would increase the pressure in that space and smoke would find ...
JACK's user avatar
  • 82.3k
4 votes

How to re-route range hood ducting to my vent?

Get custom. Despite the tubular similarity, ducting isn't rocket science. So grab some straight pipe and a tin snips, put on some good gloves and start cutting. You could even make some template ...
isherwood's user avatar
  • 140k
4 votes

Is a water heater exhaust pipe adhered or sealed in any way that would prevent me from temporarily removing it?

Generally, no. They're just a friction-fit deal, usually held with screws. Use caution to not deform the pipes. They should fit together accurately and snugly to seal against leakage. In your case I ...
isherwood's user avatar
  • 140k
3 votes

Additional exhaust vents needed for whole house fan

Okay looks like several folks have no idea what a whole house fan is or how it works. You need to check your fan rating to see how many CFM it will move. Then you need to take that number and divide ...
Mike Beaty's user avatar
3 votes

Why does my boiler vent steam?

Assuming that your boiler and mine are similar, you have two vents or pipes and the main exhaust. Main exhaust will emit carbon dioxide and water vapour, the products of combustion. A modern boiler ...
Neil B.'s user avatar
  • 101
3 votes
Accepted

How to prevent birds from entering a dryer vent?

I have installed a vent screen that looks almost exactly like the one you linked to. Mine had a plastic frame piece that screwed to the wall around the vent assembly. Then the screen part just snaps ...
Michael Karas's user avatar
  • 65.2k

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