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Community and Q&A

HVAC in unconditioned space – backdraft dampers?

KROregon | Posted in Mechanicals on

We have a 1000 square foot tract home in Walla Walla WA. (Yes, there are onions), The furnace , air handler, and ducts are in the attic. As a result, every cycle of the system sends cold air in the winter and hot air in the summer, until the conditioned air fills the ducts. Even worse, the ducts thermosiphon air in the winter, dropping cold air on us at night.

We would like to blow in more cellulose and cover most of the ducts. However, since the furnace and plenum are in unconditioned space, the air will still thermosiphon in the winter. Is it possible to add a backdraft damper like the Tamarack Cape Backdraft Damper (http://www.tamtech.com/store/backdraft-dampers-weatherization-energy-saving,category.asp) to each duct?
It’s supposed to be quiet, non-mechanical, and only allow airflow one way.

More info: The ducts are insulated, supported, and appear to be well connected to the boots etc. Our heating and a/c bills aren’t bad, our climate is mild, so i don’t want to move the whole system, just to improve it.

Thank you in advance. And apologies if my attempted link to Tamarack doesn’t work.

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Replies

  1. GBA Editor
    Martin Holladay | | #1

    Kathy,
    The best solution to all of your problems is to create a conditioned, unventilated attic. More information in these two articles:

    Creating a Conditioned Attic

    Keeping Ducts Indoors

    I would be wary of your suggested solution of installing Tamarack Cape backdraft dampers in HVAC supply ducts, for a variety of reasons. But you can always call Tamarack's tech help hotline or customer service department for their opinion. Tamarack's two phone numbers are 800-222-5932 and 508-295-8103.

  2. KROregon | | #2

    Thank you, Martin, for your super-fast reply. I so much appreciate this website and the resources in it. I will read, re-read, and discuss with my DH.

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