One of the issues to consider when adding a range hood, or replacing one, is whether it will cause depressurization problems in the house. If the exhaust flow of a range hood (or any other fan) causes high levels of house depressurization, there are some possible negative consequences:

  1. Backdrafting or spillage of vented combustion appliances, including fireplaces and woodstoves
  2. An increase in radon entry from the soil
  3. An increase of air entering the house from attic spaces or wall cavities
  4. Drafts from the outside

The bigger the fan and the tighter the house, the more depressurization that is likely to occur.

Have you encountered this in your work? Have you seen instances where a newly installed range hood requires some monitoring or the provision of make-up air? What levels of depressurization have you seen created?

Back when I was testing houses in the eighties and nineties, we saw several houses exceed 20 Pa of depressurization. Are we seeing that today?

The gradual disappearance of natural draft appliances (those with chimneys) and the availability of consumer carbon monoxide alarms have reduced some of the dangers.

We would be interested in hearing about your experiences.

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They do meet UL standards, different UL standards,   but not for alarm systems that call fire departments.

The CO detectors that are commonly bought and installed - are last ditch before "people die alarms".   The save lives,  but do not necessarily prevent CO injuries to the occupants.   If we are worried about having a healthy efficient house - shouldn't we also desire to have alarms that can warn us before the occupants are exposed to long term chronic low levels of CO poisoning.. levels that can lead to heart disease, brain injury (looking like dementia), hypertension?

Even though they might not automatically call the fire department,  perhaps its time that we start thinking about the impacts of lower levels of CO.

Worrying only about death should not be the only reason for choosing a detector.

You're preachin' to the choir. We had several in-depth discussions on this topic here, here, here, and here. Unfortunately, CO-Experts detector is no longer manufactured. I believe the ProTech 8505 is still available (see this site).

Yup,  I've read prior posts.    And I know Don's posts are six months old.   While the one particular brand is no longer available,  there are actually quite a few on the market.   Its still on topic,  one of the problems with hood design and build out,  is simply people not following it to see how it works over months are a few years.   While we are having the discussion - it may be worthwhile for members of the choir to get the low level detectors and track how effective various solutions really are.  E.g.  more than a once or twice CO check,  but monitoring our own installations for a longer period of time to see if the ideas really hold up and what the long term problems might be.

Correct,  but if we're worried about depressurizing issues - having at least one very sensitive CO detector to monitor the issue - if make up air is not being supplied.

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