Replies

1. 
   charlie_sullivan | Sep 04, 2021 11:50am | #1

   Zehnder is generally considered to occupy that position in the market. The only negative (other than cost) is that they use an electric preheater in extreme cold to combat having the core freeze up. Their even more expensive groud-loop preconditioning system is a way to avoid that if we are really ignoring cost. Others use different defrost systems.

1. 
   Trevor_Lambert | Sep 04, 2021 01:50pm | #3

   The other defrost systems all rely on reducing ventilation, which is the primary function of the unit. Ventilation requirements don't change when it gets cold outside, so it's pretty hard to justify that approach, in my opinion. It would be defensible if they recommended oversizing the unit to account for that, plus provide a control mechanism to automatically increase the overall air flow to compensate for the recirculation. They don't do either. One maker, I think it's Renewaire if I recall correctly, claims not to need any frost prevention mechanism at all. I'm pretty skeptical that is the case in every possible scenario. One thing to note is that an ERV is much less prone to frost buildup than an HRV, which is a good argument to always go with that option.

2. 
   joenorm | Sep 04, 2021 01:38pm | #2

   Do you know if a license is required to install them professionally?