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

HRV ducting, minisplits, and exhaust fans

bobhol | Posted in General Questions on

I am planning on heating my house with 2 minisplits ,one on each floor. I will have a propane fireplace as backup. Since I have no duct work the only air circulation will be the HRV..

I have read on this site an article on mini split air circulation which pulls the air from the bedrooms (farthest from the heat source )and fresh air supplies are in the center of the house ,closer to the heat source….my question has to do with exhausting the two bathrooms….would I use 200 cfm fans on a timer and vent them through the envelope as well as the range hood?…

thanks, Bob

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

    John Straube has shown that exhausting stale air from bedrooms and supplying fresh air to the living room is incapable of evening out room-to-room temperature variations. For more information on Straube's analysis, see Choosing HVAC Equipment for an Energy-Efficient Home.

    In that article, I wrote, "Some people have suggested that creative ventilation ducting — for example, a system that supplies fresh outdoor air to the living room and hallway, and exhausts stale air from the bedrooms — might equalize temperatures from room to room. Straube rejects that strategy, however. 'Ventilation air doesn’t do much to move around heat,' he said. 'Ten cfm of 72 degree air to a 65 degree bedroom won’t make any difference to the temperature in the bedroom at all. Open doors work better than HRV ducting.' ”

    I advise that your HRV should pull exhaust air from the bathrooms.

    By the way, be careful when you specify a range hood fan. You don't want a very big fan. More information here: Makeup Air for Range Hoods.

  2. bobhol | | #2

    Thank you for the clarification...using the HRV to pull exhaust air from the bathroom ,do I still need a dedicated exhaust fan on a timer to get moisture out quickly...thanks,Bob

  3. GBA Editor
    Martin Holladay | | #3

    Most HRVs are designed to allow occupants to use a switch on the bathroom wall to boost the fan speed when necessary. In effect, the HRV operates at low speed continuously, and has a boost mode when needed to remove humidity or bathroom odors. Talk to the manufacturer or supplier of your HRV for more information.

  4. bobhol | | #4

    Again many thanks....I appreciate this forum and the very professional advice ..Bob

Log in or create an account to post an answer.


Recent Questions and Replies

  • |
  • |
  • |
  • |