I'm looking to do my own HRV install and have a question about running ductwork in the attic. I plan to use regular galvanized ductwork in the attic and then insulate the whole attic area (over the ductwork) with R20 of blown cellulose (Canada)
Do you see any problems doing it this way?
Wouldn't the regular (not flex) duct give me better flow performance?
Would the lack of vapor barrier around the duct be a concern?
I live in Canada.....so there will be cold temperatures to consider. I will only be using the ductwork for ventilation......no heat or AC.
Round metal pipe will get more air through it than the same size flex duct.
There is an alternative and that is to insulate the steel pipe. I put so this all the time. I have double wrapped the insulation in colder climates to get higher R values.
The way to do this easily is to put the insulation around the pipe so that it will slide, then hook the pipe to the previous pipe, screw it, tape it with mastic tape and then slide the insulation over it.
Most would say to just ues a larger flex duct but I prefer metal to flex as it is tougher and will survive small animals that seem to like the heat and will chew through it sometimes. I have never seen an animal that can chew through metal but then again you live in Canada, eh.
My idea of a perfect day: No where to go and all day to get there.