Residential kitchen exhaust hood

[goldstar]

PROBLEM SOLVED !!! Homeowner texted me tonight and said they ordered a different exhaust hood. This one goes up to 390 cfm but has a "boost" setting to 600 cfm that can be field disabled. I'm going out to buy a lottery ticket.

 

[the74impala]

Next time, this is what you really need to do it right.

Make up Air by Fantech Looks like they are backordered right now.

No, cutting an 8" hole for a passive system will not work with a damper. To get the appropriate flow will take many 8 inch holes without a fan.

Even if it is an all electric home, with no combustion gases, it causes problems even in not so tight houses. Hope there is no radon in their basement.....

 

[FionaZuppa]

700cfm out, 300cfm in, is what the make-up is asking for (300cfm MAU min) It's just easier and more accurate to link a 300cfm in MAU to the 700cfm out unit. A MAU with it's own damper sounds about right. But what happens when the MAU fails.

 

[gadfly56]

If they find out I have 4 3/4" hole saw they will ask me to vent dryer regardless

If they ask, don't tell.

 

[gadfly56]

Next time, this is what you really need to do it right.

Make up Air by Fantech Looks like they are backordered right now.

No, cutting an 8" hole for a passive system will not work with a damper. To get the appropriate flow will take many 8 inch holes without a fan.

Even if it is an all electric home, with no combustion gases, it causes problems even in not so tight houses. Hope there is no radon in their basement.....

The IMC disagrees. A single 8" diameter penetration is sufficient to passively supply up to 317 cmf of makeup air. See Table 501.4.2

Makeup Air Supply | UpCodes

Explore a searchable database of US construction and building code. Code regulations are consolidated by state and city for easier navigation.

up.codes

 

[kwired]

700cfm out, 300cfm in, is what the make-up is asking for (300cfm MAU min) It's just easier and more accurate to link a 300cfm in MAU to the 700cfm out unit. A MAU with it's own damper sounds about right. But what happens when the MAU fails.

You might notice it is harder to open outward swinging exterior doors until you have fully broken the vacuum. Inward swinging doors however might practically open themselves once you have released the latch. Actual results here may depend somewhat on damper design as well.

 

[FionaZuppa]

You might notice it is harder to open outward swinging exterior doors until you have fully broken the vacuum. Inward swinging doors however might practically open themselves once you have released the latch. Actual results here may depend somewhat on damper design as well.

I was thinking more on the lines of bad drafting sucking in from other areas which may be undesirable. Fireplaces (wood or gas), heating units, etc. The addition of MAU needs some sort of monitoring. Most won't even know when the MAU fails. If the MAU fails to produce the expected CFM, then an alarm of some sort should be initiated. IMHO.

 

[gadfly56]

I was thinking more on the lines of bad drafting sucking in from other areas which may be undesirable. Fireplaces (wood or gas), heating units, etc. The addition of MAU needs some sort of monitoring. Most won't even know when the MAU fails. If the MAU fails to produce the expected CFM, then an alarm of some sort should be initiated. IMHO.

Punch an 8-inch hole. Call it a day.

Details matter, but that's essentially the solution.

 

[kwired]

I was thinking more on the lines of bad drafting sucking in from other areas which may be undesirable. Fireplaces (wood or gas), heating units, etc. The addition of MAU needs some sort of monitoring. Most won't even know when the MAU fails. If the MAU fails to produce the expected CFM, then an alarm of some sort should be initiated. IMHO.

Might also notice heating/cooling doesn't keep up like it should. This probably more noticeable in commercial kitchen than most dwellings where the exhaust fan likely runs for much longer periods of time.

 

[the74impala]

The IMC disagrees. A single 8" diameter penetration is sufficient to passively supply up to 317 cmf of makeup air. See Table 501.4.2

Makeup Air Supply | UpCodes

Explore a searchable database of US construction and building code. Code regulations are consolidated by state and city for easier navigation.

up.codes

Not necessarily, depending on what other types of appliances/combustion devices are in the home.

 

[gadfly56]

Not necessarily, depending on what other types of appliances/combustion devices are in the home.

We were talking about the requirements for one device. You don't strengthen your argument by making ad hoc adjustments.

 

[the74impala]

We were talking about the requirements for one device. You don't strengthen your argument by making ad hoc adjustments.

Sorry, but since the whole discussion started stating 700 cfm, then others toss out 300 cfm. My concern is that saying what you did is only valid in a very specific situation, not all. So you call it moving the goal post, I say you overly simplified a very comprehensive chart. Have a great weekend!