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Passive heat recovery – passive exhaust and supply

fitchplate | Posted in General Questions on

Ventive’s passive ventilation and passive heat recovery solution

At first I wanted a fresh air intake warming solution for passive inlets that are balancing/supplying a hybrid, exhaust-only situation. I looked for a way to pre-warm the incoming air for free; to off-set the BTU’s lost through the exhaust. There are some “warm wall” designs and “snaked” inlet piping designs that act as passive heat exchangers to incoming fresh air.

I wondered if harnessing stack-effect would work for energy free exhaust along with the passive inlets. Although that idea made the “ventilation system” passive at both ends, it would still cost to heat the make-up air.

So are there passive heat recovery ventilators to marry with the passive stack-effect air stream. As most of you know, HRV cores are passive; the energy is used to move the air, not make the heat exchanger work, per se.

I was skeptical. Could stack-effect enable optimal pressures; and not be messed up by wind and external building forces.

Then I ran across Ventive which claims to use stack effect, buoyancy and wind to move out stale air and move in pre-warmed fresh air by passing it through a passive HRV.

The Ventive S product was first designed for ventilation and heat recovery retrofits but they also have a solution using PVC piping for new construction: Ventive S+

Can a passive ventilation and heat recovery solution adequately perform when facing outdoor natural forces? It requires a roof penetration and the return is centralized; meaning decentralized passive make-up air inlets cannot be used.

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  1. GBA Editor
    Martin Holladay | | #1

    I have no experience with this; it's intriguing, but I can imagine several disadvantages. I look forward to reports from the field.


  2. mikeolder | | #2

    Ive been wondering if I built my home very tight with a HRV, and then lost lost power for a week. Or left my home for a extended time, if a passive HRV system would be a option..

    But considering how no one has said they have used one, it must not be proven.

    1. Expert Member
      MALCOLM TAYLOR | | #3


      Would there be any advantage to changing the air in an unoccupied house? I'm having trouble thinking of any.

    2. Expert Member
      BILL WICHERS | | #4

      The usual response given on this site, and the most green option in terms of both energy use and materials conservation, is “open some windows”.

      If you’re away, a few windows open a little would work. There are some windows out there that can be locked about an inch open to remain secure while also providing some ventilation.


      1. Expert Member
        MALCOLM TAYLOR | | #5

        We were lucky enough to have a summer cottage when I was growing up. It was closed off for around 10 months of the year. While it did suffer some minor moisture issues due to not being heated (mildewed sheets, and comic books), I don't think lack of ventilation affected it at all.

        1. Expert Member
          BILL WICHERS | | #6

          We have a family cottage like that too, usually closed up from late October or November through May. The only issues we’ve had are the occasional chipmunk or mouse getting in and once a bat, which we think came down through the fireplace flue. We've never had moisture issues.

          My suggestion was more along the lines of “if you want to do this, you can”, but I don’t think it’s really necessary. I’ve only ever left windows cracked while I was away after I had spray foam installed, and that was on purpose to help things air out over a weekend as I often recommend here.


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