ERV ducting - how to insulate?

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ERV ducting - how to insulate?

We have an ERV, which works great for our house, which is in a cold climate (i.e. this week will be below zero at night for the next four days, and teens during the day). This is our second winter in the new house. We have discovered that due to location, a hot water line (PEX with R-4 insulation) crosses over the ERV incoming duct in the between-floor truss level. It has frozen at this point.

We have already tried separating them with spray foam, but it has frozen again. We also found frozen condensation in the vicinity. Thermal envelope is about R-30 and includes 2-inch extruded polystyrene, so the truss zone should be warm - apart from the duct cooling effect.

How do we get enough insulation between these lines? Are we going to have to tear out the whole ERV inflow duct and replace with an insulated smaller diameter line? Currently 6 inch flexipipe.

Any suggestions? thanks in advance for your help.

Asked by Richard and Miranda Menzies
Posted Sat, 01/12/2013 - 20:35