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Q&A Spotlight

Is This Bathroom Vent Screwed Up?

A lapse in communication has left a homeowner wondering how to move forward

The homeowner thought this bathroom fan would be vented through the roof. The HVAC contractor thought otherwise, and ran the flexible duct down the length of the rafter bay and out at the soffit. Photo courtesy Leslie Warren.

Leslie Warren thought she had all the details worked out in advance with her HVAC installer, so on the day he was scheduled to install the bathroom fan she was at work. When she did return, the installation didn’t look anything like she had expected.

The bathroom has a vaulted ceiling, and the fan had been installed earlier by an electrician near the high point of the room. Instead of venting the fan through the roof directly above the fan, the HVAC contractor had run the vent line down the length of the rafter bay some 12 feet to exit the housing at the eave.

“This is not what I expected,” Warren writes in this recent Q&A post, “and I’m wondering if I should ask him to change it so it vents out the roof instead.”

Warren has a number of concerns. She wonders whether the warm air from the fan will be able to escape the building, and if it does whether it will immediately be sucked up by an adjacent soffit vent. In addition, routing the vent down the middle of the rafter bay has left very little room for insulation.

“I won’t exactly be thrilled if this ends up costing me money to have it changed, but it’s money I will gladly pay if necessary,” she adds. “This just intuitively looks wrong to me but I have no experience in what does and doesn’t work in practice.

When contacted the HVAC contractor said he didn’t want to cut a hole in the new roof. Who’s right here? That’s the question for this Q&A Spotlight.

If the roof had already been  installed, there’s no way the HVAC installer is going to cut a hole in it, Malcolm…

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One Comment

  1. Yeldog | | #1

    I really like the FanTech exterior unit ..... it does not work everywhere (looks) .... but, it's a great fan. Powerful and quiet. They last forever .. but if they every should fail you just take it off the wall and replace. I always use metal pipe or PVC ... I also like doing two intakes ( one by the toilet and another in the shower ) They are easy to install -- especially if the rafters are in line.

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