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Do I need Zhender or any ERV if i am at 1.5 – 2 ACH@50 Pascal?

yavaid | Posted in Green Products and Materials on


Do i need an ERV(i am going for Zhender ComfoAir…but not so sure now) if my house is 2ACH@50 Pascal?

Pumping in 30Grand for GeoThermal…i am wondering does it make sense to put in Zhender as i am not in sub 1ACH@50Pascal Air tightness.


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  1. Expert Member
    Dana Dorsett | | #1

    At that level of air tightness active ventilation is a code requirement, but it needn't be HRV or ERV. Even at 3ACH/50 (IRC code max) active ventilation becomes code.

    Even in leaky houses active ventilation is still a good idea- random infiltration volumes at random unknown paths don't often align well with individual room ventilation needs.

    ERV vs. HRV only makes sense at high ventilation rates in locations with high summertime dew points.

    Pumping $30K into a ground source heat pump might make less "...sense..." than the Zhender, given the improving performance and lower upfront cost of modulating ducted air source heat pump alternatives.

    But at the high efficiency of a GSHP a less expensive active ducted ventilation approach (even with pre-heat/pre-cool) might make more dollar-sense than the Zhender.

    1. yavaid | | #3

      Problem is i am having tough time convincing Mistubishi Dealer to setup a 2 Ton Single Zone Ducted...Even mistubishi guys here(Cincinnati OH) are not willing to do such a low load for 4000Sq.ft home. Although i am targetting 1ACH( worst case i might end up at 2ACH..because of Air sealing work thats to be done)...because of this challenge i am frustrated and thinking of not spending money on Air Tightness and R-30 Wall Insulation(2X6- i am using ZipR to get there). I am so frustrated because R-60 Ceiling, R-30+ Wall , R-10 Below Slab is costing me $20K ,Zhender $10K and GeoThermal $30K. When i look at the returns...i am doubting myself to have started out this route. If i had Mistubishi Certified Dealer who would do that low load i wont think of Geo Thermal.

      Do you see anything thats off here?


  2. _Stephen_ | | #2

    I will echo Dana's wisdom. My colleague and I both built highly efficient homes around the same time. He went geothermal, I went air source.

    We had a cold snap last year, and compared notes. I barely used more electricity than he did, but paid a fraction what he did.

    1. yavaid | | #4

      Thatnks Steve, Did you use an ERV? was it Zhender? Also what was your Air source?


      1. _Stephen_ | | #5

        We used an ERV, but nothing as fancy as a Zhender. We used a Venmar ECM ERV. It's not as efficient, but it was very cost effective.

        The heat pump we went with was a 2.5 ton Mitsubishi hyper heat unit, hooked up to a normal~ish air handler.

        The heat pump has been awesome, but the zoning system we coupled it with (and that Mitsubishi recommended and sold to us) has been dreadful. AC didn't work properly last summer, and we've now been 4 weeks without heat in the basement because the zone module died, and Mitsubishi can't seem to get parts for the damned thing.

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