Thermal break for a range hood vent?
I am about to install my range hood, a low cfm broan model I learned about on GBA, and will be using a luxury metals exterior vent, something I also learned about on GBA, and was wondering what I can do to reduce the thermal bridge between the exterior vent and interior hood. Normally one would use sheet metal btwn the two but this seems to create a very undesirable thermal bridge ripe for conducting undesirable temperatures in especially when it’s ten degrees outside. I have taken great pains to seal and insulate my house and am very happy with its performance, so I’d like to minimize what I presume will be a semi-significant thermal bridge. As always, thanks in advance for the advice,
Matt
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Replies
Matt,
You'll just have to live with a thermal bridge. It's a necessary part of a system that exhausts air from your kitchen to the outdoors.
Your front door is also undesirable from a thermal perspective, but it's there for a reason -- so you can enter the house. You can't eliminate your front door, so you just have to get used to the thermal penalty associated with the door.
If the exhaust duct really bothers you, you can consult your local code authority to see if you can eliminate the duct. Some Passive House builders have been given permission to use a range hood with a recirculating fan connected to a charcoal filter instead of an exhaust fan that is ducted outdoors. But even those houses have an HRV with ducts to the exterior.