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elbows in 4″ insulated venting

303z | Posted in Mechanicals on

I’m installing my first Panasonic spot ERV, which calls for insulated venting for both exhaust and intake. My runs are a 10′ vertical run down through interior wall, then a 15′ horizontal run through insulated floor joists with a termination at 9′ above grade. Located in central Colorado, air will be very dry most of the time, and winter temps are zone 5. Two questions:

1) How important is it to run insulated vent for exhaust? Question is motivated by serious lack of space in the 10′ vertical run from the ERV to the first 90-deg turn. There’d definitely be 3-4 points where the insulation would be completely compressed, which makes me wonder if those points would be prone to condensation. We are planning on insulating interior walls with fiberglass batt, if that’s a factor in this question. 

2) Speaking of that 90-degree turn into the horizontal run, I’ve unfruitfully  searched for an hour online to find any information on whether insulated venting like this requires a special insulated elbow, or insulating a standard HVAC elbow is the practice. There isn’t enough room to turn insulated vent pipe 90-degrees in this spot without seriously crimping said venting.

Obviously there’s double-wall elbows more specific to fireplaces, etc, but what’s protocol in this application? A standard elbow seems like it might be a likely place for condensation, though in this case exterior air will have traveled 15′ through insulated interior joist space beforehand.

It’s also a bit confusing on how a semi-rigid flex pipe with insulation installed all around it would be that inferior to insulated flex pipe that basically just has the same insulation wrapped around it. Or is the exterior plastic sheath on insulated pipe the key difference?

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