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Community and Q&A

Dedicated vs. Shared Ducts for ERV

sarahgrant | Posted in Mechanicals on


I’m helping a homeowner that has a boiler and a 1960s ranch-style home that is leaky and poorly insulated (R12 in above grade walls, R0 in basement, minimal insulation in the attic). He is planning to renovate and would like to get off of gas with hydronic heating in the floors from an air to water heat pump. Based on my calculations (from the energy audit), he will need mechanical ventilation.

I see two options and am curious to hear what you would do and why:
1. Install ductwork what will double for the ventilation with an ERV and a ducted air source heat pump

2. Install dedicated ducts for the ERV and continue with the planned air to water heat pump that will distribute heat via the floor

I estimate the costs for scenario 1 are about $20,000 – $25,000 while the costs for scenario 2 are $25,000 – $30,000 (not including the costs for the flooring or any renovation costs). Both heat pumps need to be cold climate (48,000 btus/h) and the two fireplaces can provide back-up heating if needed.

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  1. GBA Editor
    Kiley Jacques | | #1

    You should read this article by Martin Holladay, who says delivering ventilation air through heating or cooling ducts is a bad idea: Ducting HRVs and ERVs.

    1. sarahgrant | | #3

      Thanks. Although wondering if the same configuration and duct sizing challenges exist to the same extent wrt a heat pump.

  2. BirchwoodBill | | #2

    You may want to look at the Cerv2 with GeoBoost. The GeoBoost looks like it can take a glycol mixture from a heat pump for additional cooling capacity. The VFD air handlers will share duct work with an ERV. Check out build equinox. There is also the minotair that provides some cooling capacity.

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