Hood fan condensation issues

[B.Spilner]

So we had this issue last year where our hood fan was building lots of condensation and pouring onto our gas stove. We couldn't use the fan/stove anytime where the weather was colder then -10.

Builder came multiple times and after the third attempt found that where the vent goes through the wall was not 100% insulated. They spray foamed it a couple weeks back and said that it was fixed.

Today -20, and here it starts again. Haven't even turned on the fan today.

Anyone else having this issue or know anything about it?


Last year-
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Today
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[B.Spilner]

Pictures of the top vent. Frozen piping and starting to pool. Builder has been contacted but they are a bunch of goofballs that probably shouldn't even be building sheds.

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Last year there was a pool on top of the hood fan.

[Darell_n]

Insulate the pipe with foil back fibreglass. Is there a flap inside that vent or the outside wall outlet that is stuck open? If the airflow isn’t blocked while off the cold air is going to pour into your house like a waterfall.

[suntan]

Insulate the entire pipe. You can buy pipe insulation at HD etc.

[B.Spilner]

Insulate the pipe with foil back fibreglass. Is there a flap inside that vent or the outside wall outlet that is stuck open? If the airflow isn’t blocked while off the cold air is going to pour into your house like a waterfall.

Flap is on the exterior and they checked and confirmed its working properly.

I've suggested to them why it's not insulated and they say no need lol.

Will have them purchase some and waste their time coming back.

[littledan]

I wonder if a thermal break would help aka a short section of plastic piping right at the exterior wall to flap connection

[B.Spilner]

Keep any and all suggestions coming.

[ExtraSlow]

When was house built?

[B.Spilner]

When was house built?

House was completed November 2019. We moved in the following Feb

[MOB68]

From the frost/ice build up on the vents it look like a lot of very cold air is flowing directly down that stack. You may need to install a back draft damper.
Sort of like this: https://www.amresupply.com/part/BDD125-AEROFLO-BACK-DRAFT-DAMPER-5-inch
(you should check into any building code issues for this)

[AndyL]

Tightly sealed house (based on 2019 build) + high efficiency furnace = check your furnace air intake sizing and whether it's obstructed...

[Darell_n]

Tightly sealed house (based on 2019 build) + high efficiency furnace = check your furnace air intake sizing and whether it's obstructed...

Good call.

[prae]

Tightly sealed house (based on 2019 build) + high efficiency furnace = check your furnace air intake sizing and whether it's obstructed...

this makes a ton of sense

[ThePenIsMightier]

Does it?
I assume the theory is that the house is under vacuum due to undersized or clogged intakes. But flapper in hood exhaust should not be letting cold air in to this extent.

[Ca_Silvia13]

Insulate the pipe with foil back fibreglass.

This is the correct course of action. Not sure if it's code in a residential application but typically any duct from an exterior wall needs to be thermally wrapped for 10'.

[ExtraSlow]

Run hood fan 24h/day, problem solved!

[Xtrema]

From the frost/ice build up on the vents it look like a lot of very cold air is flowing directly down that stack. You may need to install a back draft damper.
Sort of like this: https://www.amresupply.com/part/BDD125-AEROFLO-BACK-DRAFT-DAMPER-5-inch
(you should check into any building code issues for this)

Doesn't all range hoods have one of these by default?

[Rocket1k78]

Do you know if that outside vent is facing the windy side of the house? Mines not on the windy side but during the nasty wind weve been getting i can still hear it flap now and then. Could be wind keeping the flaps open and the cold wind coming in non stop with the snow.
Might want to see if the builder is willing to replace that range hood too. I know they can handle moisture because they suck up a ton of it when cooking but its blowing it directly out and immediately, this is water sitting on potentially many of the electrical connections.

[ExtraSlow]

Builder is going to tell you to fuck off and say this is a labor and materials issue and you are out of warranty.

[AndyL]

Does it?
I assume the theory is that the house is under vacuum due to undersized or clogged intakes. But flapper in hood exhaust should not be letting cold air in to this extent.

The flappers aren't a tight seal... Just like the dryer and bathroom fan exhausts.

But the drawing cold air in - does point in a direction of this is more HVAC related than fan itself. And we know the HVAC guys have a habit of undersizing the air intake - we also know this is the time of year and conditions where we get warnings from the fire dept about CO & CO2 detectors because - vents get clogged.

It's a not insignificant draw of air - so it's more likely the path of least resistance for the airflow.

[B.Spilner]

Builder wanted to bring the cabinet company in to start to see what's happening behind the scenes, I guess?

Told them to wrap the pipe and try that before you get into demo. Pipe is wrapped, cold weather coming in wed/Thurs this week so should know if the problem is solved.

[KRyn]

B.Spilner how did things work out for you regarding this issue? In the midst of installing a hood fan and wondering how crazy I should go with the insulation.

[jeffh]

‘No need’ is bullcrap. Alberta Building Code says to have first 3m from exterior termination to interior on an exhaust vent to be thermally insulated with at least 1” thick insulation. I’d suggest 2” or double wrapping it with 1” for that entire little bit of hard pipe. Lazy idiots.

[suntan]

B.Spilner how did things work out for you regarding this issue? In the midst of installing a hood fan and wondering how crazy I should go with the insulation.

As crazy as possible.

[zieg]

Damn, I wish I saw this when it was fresh. For what it's worth anyone in this situation should also make sure the air path is not obstructed on the inside. I had an issue with a bathroom fan dripping on really cold days, everything was insulated and seemed fine on the outside. Then I realized the dumbasses who installed the fan used screws to attach the duct, and put one in too close to the backdraft flap inside the fan housing. It severely reduced the airflow. I fixed that like 8 years ago and it never happened again.

[Twin_Cam_Turbo]

Damn, I wish I saw this when it was fresh. For what it's worth anyone in this situation should also make sure the air path is not obstructed on the inside. I had an issue with a bathroom fan dripping on really cold days, everything was insulated and seemed fine on the outside. Then I realized the dumbasses who installed the fan used screws to attach the duct, and put one in too close to the backdraft flap inside the fan housing. It severely reduced the airflow. I fixed that like 8 years ago and it never happened again.

Good to know, I had issues in -30 with both my bathroom fan and my range fan last winter.

[littledan]

Check your fresh air intake for obstruction. If you starve your furnace of fresh make up air then it will pull a vacuum and any orifice in your house will start sucking more than a kardashian

[KRyn]

‘No need’ is bullcrap. Alberta Building Code says to have first 3m from exterior termination to interior on an exhaust vent to be thermally insulated with at least 1” thick insulation. I’d suggest 2” or double wrapping it with 1” for that entire little bit of hard pipe. Lazy idiots.


As crazy as possible.

Noted, I will go real crazy and at least double wrap it.

[suntan]

Dry fit the pieces first. Then use aluminum tape or mastic to seal the pieces. Then attach and seal those pieces. Don't mastic to the fan. Then duct wrap as much as you can. It also helps to keep the fan noise down.