GBA Logo horizontal Facebook LinkedIn Email Pinterest Twitter Instagram YouTube Icon Navigation Search Icon Main Search Icon Video Play Icon Plus Icon Minus Icon Picture icon Hamburger Icon Close Icon Sorted

Community and Q&A

Heat pump compressor in unconditioned /isolated / vented basement?

Matt Berges | Posted in GBA Pro Help on

Could this work in cold climate 5? Bsmt floor Sealed and thermally broken from upstairs units. Would a Vented basement make that possible?

GBA Prime

Join the leading community of building science experts

Become a GBA Prime member and get instant access to the latest developments in green building, research, and reports from the field.


  1. GBA Editor
    Martin Holladay | | #1

    The short answer is no.

    The long answer depends on several factors. The most important question: what is the purpose of the heat pump? Will it be used to provide space heat for the home above? (If so, your plan won't work).

    If the heat pump compressor is used to provide domestic hot water, the plan might work.

    Here's what happens when you put a heat-pump compressor in a basement: the heat pump makes the space colder and colder. You'll find that it's hard to get much outdoor air to flow through the basement. Eventually the basement will freeze. If you have any plumbing pipes in the basement, the plumbing pipes will freeze.

  2. Cramer Silkworth | | #2

    Assuming we're talking about the outdoor unit of a split heating/cooling system, then I second Martin's short answer. These things move 1500-2000 cfm of air for 2-3 ton units. That's quite a lot of venting for a basement.

  3. Matt Berges | | #3

    Thank you both. Yes, it is the outside unit that I am talking about, and I was trying to figure out how much air flow would be needed in this isolated, unconditioned space. What I was trying to describe was an unfinished, unconditioned, isolated basement that is cut off from the rest of the building, except by outside access. I figured I would have to cross vent the basement well, but had no idea of how much would be needed. The project is in a area where I was worried about the outside units walking away. There would be no exposed plumbing in the basement (for fear that it would freeze anyway, even without the heat pump compressor). Anyway, I dont think I have any new info that would change your thanks!

  4. Expert Member
    Dana Dorsett | | #4

    Air source heat pumps need access to their source- the great outdoors. Cooping them up in a basement would just kill them on efficiency, cooling the basement to below the outdoor air temp in winter.

  5. James Morgan | | #5

    Yep, nice try but no cigar. Stealing heat from the house to heat the house: robbing Peter to pay Paul

Log in or create an account to post an answer.


Recent Questions and Replies

  • |
  • |
  • |
  • |