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Community and Q&A

Dedicated ERV system and Bathroom Exhaust

user-1063388 | Posted in Mechanicals on

We are designing a dedicated ERV (recouperator) duct system in a high efficiency remodel. The question has arisen regarding the bathroom exhausts and whether we can utilize the ERV exhausts in each bathroom and a booster switch (dual function timer) in lieu direct vent bathroom exhaust fans. Thoughts? Ultimateair does not to take a strong position on it in their literature.

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  1. user-626934 | | #1

    Yes, you can do this, but you don't necessarily have to install the booster switches. Design these exhaust branches to the code required continuous exhaust (typically 20cfm for bathrooms), then install and test/balance the airflows.

  2. jnarchitects | | #2

    Here is a link to a previous discussion. I would agree with John above. Many HRV/ERV's offer the ability to increase fan speed when necessary via a point source switch.

  3. GBA Editor
    Martin Holladay | | #3

    My vote is to stick with the ERV -- don't install separate exhaust fans in your bathrooms.

  4. Yxb7CwDmob | | #4

    You maybe required by code to have seperate ventilation for bathroom due to contamination build up in an air to air exchange ventilator, which could cause sick building sydrome or mold propagation. check with local building code and or International Residential Code

  5. GBA Editor
    Martin Holladay | | #5

    There are no such prohibitions in the International Residential Code, to the best of my knowledge. Please cite a relevant section.

    According to section M1507 of the 2006 IRC, bathrooms need at least 50 cfm of intermittent exhaust ventilation or 20 cfm of continuous exhaust ventilation. The exhaust air must not be recirculated into the house or discharged into an attic or crawl space. An HRV complies with all of these requirements as long as it provides either 20 cfm continuous exhaust or is capable of 50 cfm of intermittent exhaust.

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