Dear HVAC designers

Something to consider:

"Wow the exhaust fan in this bathroom is waaay too powerful" -- Said no one ever.

I don't know... the sound of a Harrier Jet overhead can really ruin the mood...

Supe said:

I don't know... the sound of a Harrier Jet overhead can really ruin the mood...

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Right, because we don't want the fan to drown out any of the sounds coming from the stalls.

If I've indulged in the musical fruit, others should appreciate the resultant music.

is that really something that the HVAC folks "design"?  or more like something that gets bought at a store and installed?

Road Guy said:

is that really something that the HVAC folks "design"?  or more like something that gets bought at a store and installed?

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In a commercial building, HVAC guys spec in the fan to use.

I just figured it would be some sort of building code. i.e. for a XX stall bathroom in a XX facility use minimum XX "fart fan"

Road Guy said:

I just figured it would be some sort of building code. i.e. for a XX stall bathroom in a XX facility use minimum XX "fart fan"

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Building codes may be at the root of the issue.  But, as you note, they likely read Minimum...

I also think if you have one of those half bath rooms in the main floor of your house (for guests) that it should also be equipped with a higher "capacity" fan!

When I "designed" the renovation of my last house, i put in oversized bathroom fans and it was worth it!

Dleg said:

When I "designed" the renovation of my last house, i put in oversized bathroom fans and it was worth it!

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I guess @Supe will be disappointed if he ever visits.

LOL.  Well, I don't live there anymore, and my more standard American-style home now has more standard, American-style vent fans int he bathroom.  It takes a looooong time to clear the stench.

yeah you defin have to buy the $150 dollar one for it to "really" work. the cheap builders grade ones are fairly worthless.. sort of like the low flow toilets..

Road Guy said:

yeah you defin have to buy the $150 dollar one for it to "really" work. the cheap builders grade ones are fairly worthless.. sort of like the low flow toilets..

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My cheap builder grade is so bad, that it can't even spin up until full power unless you pull the grate off for some reason, at which point it speeds up to full tilt (and can stay there if you put the cover back on).  Of course that's all moot, because the asshole builders didn't duct it out of the soffits, just TO the soffits, so if its cold outside, the moisture condenses, accumulates, and then runs down the soffit onto the drywall and leaks.

The IMC calls for 50 or 70 CFM per fixture depending on use.  I used to design the fans to 75 CFM per fixture or 2 ACH per hour, whichever was greater.

Audi driver said:

In a commercial building, HVAC guys spec in the fan to use.

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It was VE'd

Must be spec'd for sh!t hitting duty. 

Code used to require 2cfm/SF, but now its about 70cfm per potty/urinal.  Not sure how they came to either of those values, but 2cfm/SF could sometimes wreak havoc on building air balance in the old days if you had large restroom groups.  Not to mention your throwing perfectly conditioned air outside.