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Cold Climate version of ERV/ HRV for Climate Zone 5A?

JHCT | Posted in General Questions on

Hi everyone.

I’m in the process of purchasing a home that’s located in climate zone 5A. I’ve been looking at HRVs and ERVs however I can’t seem to find a clear answer about whether we should be using a model specifically marketed for Cold Climates. I’ve reached out to local HVAC folks, however no one seems particularly familiar with the nuances of balanced ventilation since exhaust-only is the standard in our neck of the woods. 

Is 5A “cold enough” to warrant the Cold version of an HR/ERV? 

A few details about the house/project: 2000′ SF colonial. Double pane windows, but otherwise typical mid 1970’s construction. Central Air/Forced Air Heat. 

Thanks in advance.

-J

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Replies

  1. Trevor Lambert | | #1

    I did a lot of reading on different HRV and ERV options when I was sourcing one for my house (zone 6). I never saw any reference to any cold climate models. Just look at the specs at HVI.org, pick the best one that fits your budget and has the features you want. If looking at advertised specs, make sure you're looking at sensible recovery efficiency (SRE) and not apparent sensible effectiveness (ASE). The former is the true measure of efficiency, the latter is just used for advertising because it's a higher number (does not account for energy used by the device).

  2. Expert Member
    Dana Dorsett | | #2

    Some ERV cores can be damaged by frost build up, most HRV cores are pretty robust, and may need smarter defrost cycles in climates where it stays WAY below freezing for weeks or months. For most zone 5A locations just about any HRV would not be a problem.

    Consult the manufacturers' documentation (including warranty) about operating ERVs in sub-freezing temps. The ERV core in Panasonic's nice bathroom fan sized ERV has specific warnings, and it's internal controls change up it's operation at different outdoor air temps to protect against frost damage.

    In zone 5A the additional advantage of ERV vs. HRV is hard to rationalize except at very high summertime ventilation rates in high-energy price locations (and even then...) In zone 2A it might be "worth it".

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