Insulating / sealing gap between kitchen hood duct and ceiling drywall

riguy

I just had a range hood installed, our kitchen had no vent previously. Venting straight up through the roof (no second story over the kitchen).

Due to a mistake on my contractor's part, the duct is installed but the square 'chimney' sheet metal cover around it is not. We have to order a new one, which will take a few weeks from the mfg. What exactly went wrong with the contractor is a long story with cuss words, so I will skip it.

The 7" duct goes into a soffit, then up to the roof. The contractor cut about a 10" square hole in the soffit bottom (drywall). Clearly, there is a lot of space around the duct, partly because a transition piece from the hood to the duct does intrude into the space. Photo attached.

There is a lot of cold air pouring down through that gap. I'm not sure if the soffit was always exposed to cold air, but it clearly is now.

Eventually, there will be a 12x12" square sheet metal cover in place between the hood top and the soffit bottom. But it ocurred to me that the cover isn't likely to be air tight, plus sheet metal isn't a great insulator in any case. I wondered if we can do something to reduce the cold air infiltration into that chimney box, or at least do something temporarily while we're waiting for the duct cover.

Can we do something like stuff fiberglass batting into the space between the duct and the drywall around it? For the long term? At least for a few weeks? Assume that we have no access into the soffit or roof area, just getting at it from below through the existing opening.

And just out of curiosity, what would have been the right way for the contractor to handle this? If the answer is this is normal, the chimney would normally be full of cold air, that's fine, but if there's yet another reason I should be unhappy with the guy, I might as well add that to the list...

Thanks and happy New YEar!

heathead

In the picture it showers duct tape, although it duct tape it's not for duct's. It will dry out. I would have it re taped with foil tape, then fill it with fire block spay foam. Just my thoughts. Could just fill with fiberglass will slow down air flow but not stop it.

riguy

I was pretty unimpressed when I saw the duct tape too. But there is a long list of "unimpressed" with this job, unfortunately. Apparently just because a contractor has great reviews on Angies list doesn't mean they aren't a lazy moron.

Techman

Could that duct transition piece be put in above the ceiling, leaving the exposed duct the same rectangle size as the oven exhaust opening? that would fill the ceiling opening a little better.

TomS

I am surprised that there is no electrical box for the three electrical connections.

Gordy

Was that soffit constructed in the remodel, or existing?

he, or you need to go in the attic, and heal the hole around the duct projection through the main ceiling to stop cold air dumping into soffit. Not the soffit itself only. Doing just the soffit will still allow cold air into the soffit area. That is not good.

Gordy

If the drywall on the ceiling, and wall does not intersect in the corner ( ceiling to wall inside the soffit) then it's not correctly constructed. It's hard to tell from the pic but I don't see drywall on the wall behind the duct.

riguy

Quick answers:

1. Soffit was pre-existing, this install cut into it.

2. Fortunately, there is drywall continuing up the wall and along the ceiling into the soffit, all the way to the corner.

From what I can see (limited of course), he made a surprisingly large and jagged hole in the ceiling drywall and whatever wood is up there, even larger than that soffit hole.

3. There is no attic space to get into, per se -- the kitchen is part of a one story extension to the house, so the roof is maybe 1 or 2 feet above the kitchen ceiling at that point.

4. Yep on the exposed wire nuts. That will all be in the chimney cover and so not accessible, but yes they should be in a box. DId I mention "long list" of reasons I'm unhappy with the work?

Between the workmanship and the fact that the guy's customer relations skills make his workmanship look good, this contractor and I are done, period. As the list of things done wrong gets longer, I'm increasingly thinking I'm going to want to get someone else out here to actually fix stuff -- probably just remove the soffit and patch up the ceiling properly.

Assuming we have a some weeks before that work gets done, what about my idea of some fiberglass batting for now? Any other suggestions for a temporary improvement?

Gordy

If the only access is from bottom then fiberglass batt is about as good as it gets. If the hole was reasonable I would suggest spray foam.

Tinman

I've seen much worse than this! I agree that foil tape should have been used and the electrical connections should be in a box. As far as the way he cut the soffit, I can't comment on that without knowing what he was up against in terms of the amount of room he had to work with above. In any case, it's all an easy fix. Put some foil tape on after removing the duct tape, get the wires inside the box and cover, stuff some insulation in wherever you can, and the drywall can even be patched without too much effort.

icesailor

Vented range hoods suck!!!

The Energy Police get all sweaty about some minor leak around a door, then order you to install a big vacuum cleaner to suck the heat out of your kitchen and house. They make unvented range hoods. If you have a vented range hood in a modern tight house, it is only going to vent your hard earned heat money to the outside. They make unvented microwave hoods to.

I look at vented range hoods like I do French Doors that leak water. If Jesus Christ was a carpenter, with all his other Godly Skills, he couldn't stop a French Door from leaking in the wind and rain.

If Jesus Himself tried to stop the cold air infiltration from a vented to the outside, range hood, he couldn't do it.

I've seen multiple super tight houses where the smarter ones put bigger blower wheels in because the vent wouldn't vent when the windows and doors were closed in winter. I wonder where the make-up air comes from for the atmospheric boiler or water heater. Or the bathroom fans when they are running.

Just wondering.

SWEI

Variable speed fans on vent hoods rock. The generic high/low fans most hoods come with are inadequately fast on low speed and inadequately slow on high. IMO a tiny bit of airflow (like 50-80 CFM) should engage whenever the gas-fired oven or stove is in use in order to move the combustion byproducts out. Higher speed(s) can be selected by the user in order to handle smoky or steamy situations. Appropriate MUA required, of course.

riguy

icesailor: that's a valid set of priorities, but we do a lot of serious cooking and the ability to move large quantities of smoke and steam out of the kitchen is worth some loss of heating efficiency to us. Plus in the summer a/c season, I'd think that replacing clouds of steam and very hot air vented from the oven with outside air -- warm, but less warm and less humid than what's over the stove -- might even make sense.

And in our case, it's a 1940 house that's not airtight. A recent blower door test showed 2400cfm at whatever the standard pressure is for such a test; that was down from 3150 before some air sealing work.

SWEI: we do indeed have variable speed and light, and in fact via big and heavy rheostats in this hood. Less efficient than electronic controls, but there are so many reports of circuit boards failing quickly in other hoods -- do I really need a touch screen to change a fan speed? -- that I decided to go old school. USA manufactured and 7 year warranty, too. All the more reason that finding out my installer is a lazy moron makes me angry.

ChrisJ

icesailor said:

Vented range hoods suck!!!

The Energy Police get all sweaty about some minor leak around a door, then order you to install a big vacuum cleaner to suck the heat out of your kitchen and house. They make unvented range hoods. If you have a vented range hood in a modern tight house, it is only going to vent your hard earned heat money to the outside. They make unvented microwave hoods to.

I look at vented range hoods like I do French Doors that leak water. If Jesus Christ was a carpenter, with all his other Godly Skills, he couldn't stop a French Door from leaking in the wind and rain.

If Jesus Himself tried to stop the cold air infiltration from a vented to the outside, range hood, he couldn't do it.

I've seen multiple super tight houses where the smarter ones put bigger blower wheels in because the vent wouldn't vent when the windows and doors were closed in winter. I wonder where the make-up air comes from for the atmospheric boiler or water heater. Or the bathroom fans when they are running.

Just wondering.

You would recommend an unvented (pretty much useless) range hood with a gas range?

Larger hoods require a makeup air damper to be installed which opens when the hood is on. This will force the hood to pull air directly from near the stove rather than throughout the house. Such a damper could be installed with all vented hoods though only most of the hoods people buy are useless enough that why bother.

I run a 200-400CFM variable speed hood and I'd never go back to the lame we one we had in our apartment. Don't dare clean the oven or cook something smoky without every window open and box fans in several.

ChrisJ

To the op, if this is a temporary thing I would stuff some fiberglass insulation up there and then maybe use some tape around it just to keep the stuff from falling down into the kitchen until things get fixed.

As you already said that electrical connection is dangerous and must be fixed.

Which hood did you decide to go with?

SWEI

I prefer downsized commercial fans mounted to the roof or the sidewall (Greenheck CUE/CW with a Vari-Green motor.)

Tinman

I agree...getting a homeowner to agree to the aesthetics of a commercial grease (upblast) fan is a difficult thing to sell.

vaporvac

I have an older Vent-a-Hood with a light which works very well. It was originally designed to turn on when one pulls open a fake wooden covering. I installed with a staionary surround and switch. Is there any way to retrofit this to work at variable speeds? (Don't mean to change the subject of the post.)

ChrisJ

SWEI said:

I prefer downsized commercial fans mounted to the roof or the sidewall (Greenheck CUE/CW with a Vari-Green motor.)

Stephen Minnich said:

I agree...getting a homeowner to agree to the aesthetics of a commercial grease (upblast) fan is a difficult thing to sell.

I would've loved such a vent, but the cost is so far out of my reach I'm just as likely to buy a Duesenberg.

riguy

The hood is an Imperial.

SWEI

ChrisJ said:

I would've loved such a vent, but the cost is so far out of my reach I'm just as likely to buy a Duesenberg.

If you include a Vari-Green motor, the cost is similar to a moderately nice hood from the appliance stores. Of course you still need a hood, but there are still built-in architectural elements and vintage hoods that need sprucing up.

riguy

Btw, on the electrical issue, I think I see why the contractor did what he did. Well, or instead of lazy he's just a total idiot.

There is an electrical junction box internal to the hood. The intended installation is that Romex should come in from the wall and be threaded into a hole in the hood top, that opens into that junction box. The wire nutted connections are then sealed in there.

In my case, I suspect there was not enough slack in the existing cable to pull though the hole and down far enough into the hood to do the connections. So instead the guy just pulled the hood wires up and out of the junction box to meet the Romex and left the connections hanging in the air above the hood.

I assume the right answer would have been to put another junction box in the wall and add more NM, right? For that matter, I'm pretty sure that behind the hood, the cable just comes out of a hole in the drywall, not through any sort of box.

Or maybe I'm wrong and there was enough slack and he was just totally stupid and did it this way because he didn't realize / care there was a box in the hood. He didn't leave me the owners manual, installation guide, or warranty proof-of-purchase (believe me, I'm pursuing that one), so who knows if he even looked at the install sheet.

It really irks me when I'm paying licensed contractors good money to do stuff that even I as a novice homeowner know is dead wrong.

kcopp

why did you up through the roof and not out the side? You could use some foam board insulation to slide up to the vent and seal the gap w/ spray foam. The cover will hide the foam board.

KC_Jones

The wiring connections are supposed to be inside the box per code. Adding a junction box in the wall is only legal if the cover for the box is exposed on the face of the wall. Hidden junction boxes are illegal last time I checked. If the cable wasn't long enough and you didn't want a junction box showing through the wall his only code legal option is running a new wire. It happens sometimes and it stinks, but to be proper that's the way it is. I see so many people downplaying the importance of electrical safety (not you the contractor in this case). There are more fires from electricity than gas and people freak out about gas.

Paul48

As for the wire being too short......You can't bury a junction box in the wall. If it requires pulling new wire from an appropriate location, then, it is what it is.

riguy

Thanks for all the input!

kcopp: the stove does not back to an exterior wall. Also, if we did a turn and ran it horizontally a few feet along the interior wall to the closest exterior wall, a side vent there would be located right under our patio awning.

kcopp: On the foam board and foam, mostly I want to be sure I use materials that are OK for contacting the vent duct, which is why I thought maybe fiberglass was the way to go. I know it shouldn't be hot like a boiler exhaust, but I'd imagine there are still fire safety concerns. Is it legit to have foamboard or that expanding spray stuff in contact with a range hood exhaust duct? Those do seem to have some advantages over batting.

KC_Jones and Paul48: I know buried boxes are prohibited, but I would have been fine with a junction box visible on the wall -- and still would be for a fix. I didn't get the chance to have an opinion on the subject; the guy just did it.

Kind of like he encountered some preexisting drywall cutouts (there was a cabinet that was removed that had covered them) and just left them, now difficult to access to patch. He acknowledged they had all the materials and that he would have charged me like $25 in labor, but since I had not specified 'fix any drywall holes that you find', they didn't patch it and did not bother to call me when they found the holes to give me the option of having them patch it.

Paul Pollets

Hopefully, there's a backdraft damper installed on the venting. Insulation can be applied around the duct to minimize cold drafts before trimming out the opening. Poor workmanship, to say the least...

riguy

PaulP: Yes, there is a damper

icesailor

If I get that much smoke, my Smokes start honking. I hate that. I don't burn things when I cook. I use my outdoor grill no matter how cold it is outside for burning things like meat.

Gordy

Off topic:
Ice, I can't believe you would eat your grilled meat cremated.

ChrisJ

Very off topic,

99% of my cooking is done on either my gas Weber or charcoal Weber. I just bought a rotisserie for it and installed a GFCI next to the grill's location just so I can rotisserie any time I want. I rarely use the stove but I cook eggs and French toast on it, and my French toast can get smoky because I cook it hot.

Also our self cleaning oven smokes a lot, as does any. My 440CFM vent hood pulls all of it away, kitchen stays smelling good.

Not to mention, ANY gas appliance should be vented. I never light a burner without the fan running on it's slow speed.

icesailor

"" Off topic:
Ice, I can't believe you would eat your grilled meat cremated. ""

It can be partially cremated on the outside. As long as I had to catch it before going on the Barby. As long as it isn't cold in the middle.

With pork being the new beef (because of price), Costco has some really fine boneless pork chops. I'm so grateful that hog gave up its life just for my enjoyment. That and those $4.99 store cooked rotisserie chickens. Poor chickens. GOOD though.

MikeL_2

Riguy,
I'm not sure where you are located, but here in the Northeast, that type of installation would create the perfect environment for ice damming...................

Gordy

icesailor said:

"" Off topic:
Ice, I can't believe you would eat your grilled meat cremated. ""

It can be partially cremated on the outside. As long as I had to catch it before going on the Barby. As long as it isn't cold in the middle.

With pork being the new beef (because of price), Costco has some really fine boneless pork chops. I'm so grateful that hog gave up its life just for my enjoyment. That and those $4.99 store cooked rotisserie chickens. Poor chickens. GOOD though.

Off topic again because I think this thread has been answered.

Beer butt chickens are souding goodly.

KC_Jones

We should get Dan to put a "fun" section or "none heating" section for some of these random topics that pop up on occasion.