Make up air has to be addressed as a system operation and safety issue.
In areas with extended periods of cold winter weather suitable energy saving heat exchangers for intake/exhaust air may need to be considered.

laat,

Very true but there is no system that I know of that can do heat exchange from outside replacement air that is then being vented out the chimney.

A regular heat exchanger is just meant to exchange normal household air either on its own or via HVAC system. This does not do anything for makeup air. Its a balanced in and out or existing air.

The heat exchanger principal is needed but for the higher power hoods, you need intakes that match the output. Having a variable sped blower also complicates this as well, since the amount of makeup air is determined then by the speed set on the blower. I have been looking into ways to solve this issue for when I do this remodel.

OK:

6. Make-up air. When you suck large enough volumes out of your house, if the house is closed sufficiently that there is no way to replace air that is being withdrawn, the fan will slow down - among other problems. I'm not sure how this is addressed; one-way valves somewhere, in basements, chimneys, etc. In cold climates the coldness of that air intake is an issue. In some municipalities code has something to say about this. Redressing the air imbalance can be very expensive.

the lack of makeup air can cause worse problems than slowing down the fan - it can cause your furnace to backdraft.

Having too much suckage and not enough make-up air can cause any flame to backdraft, including a gas dryer, water heater, stove or fireplace, in addition to the furnace Weissman mentioned. This not only interferes with operation, but can lead to unburned gas and effluent entering the living areas. If the appliance/fireplace isn't venting correctly because of the superior pull of the range hood, there can also be carbon monoxide issues (though I haven't heard of anyone actually getting sick from it it's not something to take lightly). In the Southeast they are concerned with MUA being cooled and dehumidified, as opposed to being heated.

There were discussions of motors, fans, the Vent-a-hood system, and other mechanical stuff when I was shopping. A Google search might turn up those threads.

Good summary.

About 5. Noise.

A motor next to your head is louder than a motor farther away. Noise (power) diminishes the farther away the source of noise is. The blower motors they put into hoods are called "internal" (dumb name but it applies to them selling you a box with a blower inside). Go to an in-line blower or external and you get a lot less noise than an "internal" blower. End of story. You could also get fancy with specifying that an in-line blower should be at least such and such a distance, but I don't think it's needed.

About 1.

" A hood to contain the capturing apparatus, or "liner" (aka "insert") .... filter "

Other terms have seen: canopy capture volume sink

I find it must do more than hold the filter. It is a part of the "trapping" function. It stops the rising air from going higher. Or, it should do that. I'll agree that most don't do that.

hth

Thanks for the updates. Bummer about the MUA (Make Up Air). Seems these ranges have gotten too fancy for safety, potentially.

In figuring needed cfms note that everyone seems to use max *potential* btus from the range, whereas in reality, it's hard to envision actually using, say, 6 burners at 23K each all at once. YMMV and it may pay to calculate a more realistic, personal max btu output. Though note that providing more cfms than strictly necessary has its advantages.

Likewise in determining how much extra capture area past the dimensions of your stovetop, your personal requirements will depend on the size of your pans (and cooking style). As davidrol notes, accounting for that additional capture-function may be more expensive in acreage, but (potentially) cheaper in cfms.

I read an article a while back, don't have the reference, that said that homeowners were being oversold CFMs by hood manufacturers and salespeople and that for MOST home applications, 600 CFMs were more than adequate, particularly since people rarely run all their burners on max. Clearly if you have a grill, that's a different story. In most locales, 600 CFMs doesn't require makeup air but some northern states require it for anything over 300 CFMs.

How do you determine (and/or prove to an inspector) your make-up air situation? I am presuming with an old house there's leakage everywhere, but my presumption that this is enough may be wrong: how do I know? I presume there is some metric short of popped eardrums...

You don't have to prove anything to an inspector other than the specs for your hood (and possibly your range). Code will usually say you need makeup air with more than xxx CFMs so if your hood is xxx CFMs or less you're fine - otherwise you will need a make-up air system - house leakage doesn't count.

Code never used to require hoods at all but now some locales are requiring you to have as many CFMs as the manufacturer of the range recommends.

"If the blower is distant from the hood, it should be stronger in order to accomplish the same clearage of gunk."

For a given blower design, the total pressure loss determines the reduction of of flow. It doesn't matter whether it is behind or in front of the fan. There is the fact that one can generate more pressure (with an air compressor, say) than one can suck vacuum, as there is only so much vacuum to suck, but this is not a consideration when the pressure losses are in the 0.1 inch of water regime as in the case of a kitchen hood.

Also, the ducting may not be the largest source of pressure loss. The baffles or mesh filter is one significant source, lack of make-up air another, and hood to duct transition a third.

kas

My inspector didn't care a rap about the cfm. The gas shutoff, yes. They check that on each and every inspection. They're much more strict about make-up air where it's impractical to open a window.

check. makes sense.... thanks plllog. I'm writing that worry off and concentrating on the other 4,386 on the list then.

Like, how to mitigate noise on the roof. Will the attic roof help? Can I build a drywalled box around the vent pipe section that houses the blower? Can I encase it in a vacuum ;) -- just kidding, Kas ....

but if it's really +/- 80dB or +/- 15 sones, that's seriously noisy. I bet it will scare the rodents from the attic. I'm worried the bees may take up residence elsewhere though...

Here is a link that might be useful: Fantech specs