Bath Fan with Makeup Air

mkgrady

Senior Member
Location
Massachusetts
A customer is building a new house in Scituate, Mass. He is asking me to include bath fans with makeup air. He mentioned Panasonic makes them. Anybody know what he is looking for. He is not sure what they are. He says its a building code requirement. I looked at a Panasonic bath fan brochure on line but I still don't know.
 

qcroanoke

Sometimes I don't know if I'm the boxer or the bag
Location
Roanoke, VA.
Occupation
Engineering
A customer is building a new house in Scituate, Mass. He is asking me to include bath fans with makeup air. He mentioned Panasonic makes them. Anybody know what he is looking for. He is not sure what they are. He says its a building code requirement. I looked at a Panasonic bath fan brochure on line but I still don't know.
AFAIK makeup air is what the fan needs to work. Which is a vent through the wall or door of the bathroom or a heat duct in the bath.
It needs a source to draw air from. If the room is airtight it won't move any air.
 

mkgrady

Senior Member
Location
Massachusetts
AFAIK makeup air is what the fan needs to work. Which is a vent through the wall or door of the bathroom or a heat duct in the bath.
It needs a source to draw air from. If the room is airtight it won't move any air.
Right, thanks I understand all that. There is something special about the fan he wants to meet the energy code. I believe it functions as as makeup air for the whole house somehow,not just the bathroom
 

charlie b

Moderator
Staff member
Location
Seattle, WA
Your customer is using the phrase "make up air" incorrectly. He also is confusing the purpose of a bath fan with the purpose of providing fresh air into the house. A bath fan will take the not-so-fresh air from the bathroom and send it outside. It does not, and cannot, bring fresh air into the house. You need something else to do that job, something with a much higher capacity for moving air than you would ever get from a bath fan.

I suggest you speak with this customer and try to get clarification of his design intent. Also, if he claims that there is a building code requirement at play here, then ask him for chapter and verse.
 

qcroanoke

Sometimes I don't know if I'm the boxer or the bag
Location
Roanoke, VA.
Occupation
Engineering
Your customer is using the phrase "make up air" incorrectly. He also is confusing the purpose of a bath fan with the purpose of providing fresh air into the house. A bath fan will take the not-so-fresh air from the bathroom and send it outside. It does not, and cannot, bring fresh air into the house. You need something else to do that job, something with a much higher capacity for moving air than you would ever get from a bath fan.

I suggest you speak with this customer and try to get clarification of his design intent. Also, if he claims that there is a building code requirement at play here, then ask him for chapter and verse.
Or the part number of the fan he wants.
 

wwhitney

Senior Member
Location
Berkeley, CA
A bath fan will take the not-so-fresh air from the bathroom and send it outside. It does not, and cannot, bring fresh air into the house. You need something else to do that job, something with a much higher capacity for moving air than you would ever get from a bath fan.
Some bath fan manufacturers have a kit consisting of a programmable controller and a (remotely located) motorized intake damper that allows using the bath fan for whole house ventilation. E.g. Panasonic SelectCycler.

As to the ventilation rates required, for medium sized homes a bath fan can do the job. If I recall correctly, ASHRAE calls for a residential ventilation rate of 0.35 air changes per hour. So for a 2000 square foot house with 8 foot ceilings, that's 5600 CF per hour or 93 CFM, which is well within the range of bath fan capacity.

Cheers, Wayne
 

GoldDigger

Moderator
Staff member
Also to the point, a high efficiency house with minimal air infiltration will need a forced air exchange with the outside for comfort and safety.
To avoid energy loss an air exchange system will run outgoing air and incoming replacement air through a heat exchanger so the outgoing air heats (or cools) the outsidevair coming in.
It is possible that the HO is thinking of such a unit on a smaller scale for bathroom use.
The fan functions both for odor removal and reduction of excess humidity.
 

growler

Senior Member
Location
Atlanta,GA
A customer is building a new house in Scituate, Mass. He is asking me to include bath fans with makeup air. He mentioned Panasonic makes them. Anybody know what he is looking for. He is not sure what they are. He says its a building code requirement. I looked at a Panasonic bath fan brochure on line but I still don't know.

What does this have to do with electrical? Let the HVAC contractor figure it out.
 

mgookin

Senior Member
Location
Fort Myers, FL
The mechanical code has a requirement for "Balanced Air" which is easily understood when thinking of restaurant kitchen hoods. The industry common term is "makeup air".

As far as the requirement to introduce fresh air into a building, I always understood residential units to be exempt because "habitable" spaces have existing requirements for light & ventilation. You can open doors & windows if you have stale air. It's commercial occupancies where you get non-operable windows and large areas relative to door openings.

I agree he should have his mechanical contractor design the systems; you don't want it on you. Once the mechanical guy gives the owner what he wants, you can wire it for them. It's not an area of expertise for an EC and it is for the HVAC contractor.
 

qcroanoke

Sometimes I don't know if I'm the boxer or the bag
Location
Roanoke, VA.
Occupation
Engineering
Some bath fan manufacturers have a kit consisting of a programmable controller and a (remotely located) motorized intake damper that allows using the bath fan for whole house ventilation. E.g. Panasonic SelectCycler.

As to the ventilation rates required, for medium sized homes a bath fan can do the job. If I recall correctly, ASHRAE calls for a residential ventilation rate of 0.35 air changes per hour. So for a 2000 square foot house with 8 foot ceilings, that's 5600 CF per hour or 93 CFM, which is well within the range of bath fan capacity.

Cheers, Wayne
I had no idea of such a thing.
I don't do residential, most of our stuff is equipment shelters.
 

david luchini

Moderator
Staff member
Location
Connecticut
Occupation
Engineer
A customer is building a new house in Scituate, Mass. He is asking me to include bath fans with makeup air. He mentioned Panasonic makes them. Anybody know what he is looking for. He is not sure what they are. He says its a building code requirement. I looked at a Panasonic bath fan brochure on line but I still don't know.
I think he's talking about a continuous ventilation fan, which is an option on some of the panasonic fans...look up FV-VS15KF1 on the panasonic website.

The fan will provide a continuous lower ventilation rate, and will switch to a higher ventilation rate when activated by the fan switch.
 
I think is what your customer is referring to is the Panasonic WhisperSupply Wall which supplies filtered make-up/supply air. They make two versions of this fan, 1 which is 10cfm and uses a 4" duct (FV-01WS2) and the second which is a 20 cfm fan which uses a 6" duct (FV-04WS2).
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Electrical Contractor
I have never heard about needing makeup air for a bath fan but most of the range hoods we see installed are required to have makeup air but those units are large cfm. I think if the hood is larger than 600 cfm it must have makeup air or it will put negative pressure on the newer homes that are so tight.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Electrical Contractor
Correction to above-- it appears the code is 400 cfm

The International Residential Code Section M1503.4 and the International Mechanical Code Section 505.2 require Make-Up air for all domestic range hoods in excess of 400 cfm. States such as California, Wisconsin, and Minnesota have different requirements, as does ASHRAE 62.2. Always check with your jurisdiction for specific Make-Up air requirements and code amendments that are applicable in your area.
 

GerryB

Senior Member
What does this have to do with electrical? Let the HVAC contractor figure it out.
I think you are right. I did a high efficiency type house 3 years ago with a geo thermal system. House had spray foam insulation. If I remember there were some outlets in the attic needed for fans in relation to this system.
 

Buck Parrish

Senior Member
Location
NC & IN
I've wired them in a couple of houses. The HVAC guys handled it. We just ran the 120 volts.
We use to install the fans until they started requiring that insulated duct be used.
I'm glad to be done with them. The electricians have enough to do in some of these custom homes.
 

ptonsparky

Senior Member
Location
NE (9.06 miles @5.9 Degrees from Winged Horses)
Occupation
Electrical Contractor
My brother did the testing on our new home a few years ago and I gave the results to #1 born daughter. She informed us we were on the borderline of needing forced fresh air intake. It didn't sound like it took a lot, other than needing to be the heat exchanger style.

When my brother did a check on our previous 1914 home he looked around and told me "You have one hell of a big hole someplace."

Went from one extreme to the other.
 

mkgrady

Senior Member
Location
Massachusetts
Thanks for all the responses. I ran into the customer tonight at a local restaurant. I suggested he give me a catalog number. Once I see that I will decide how to proceed based on what the thing is
 

edlee

Senior Member
Thanks for all the responses. I ran into the customer tonight at a local restaurant. I suggested he give me a catalog number. Once I see that I will decide how to proceed based on what the thing is
Panasonic is making fancy bath fans that will run continuously at a low volume and then you can kick up temporarily for bath exhaust. This is likely what your customer is talking about. They are very sophisticated and have plug-in modules that can be added to make the fan do different things (humidity control, LED night light, etc).

I have wired a number of them at this point. But FYI: the wiring is different than a conventional fan and if you get it wrong on the rough-in, it will be a huge PIA! They require a constant feed to the fan unit itself, along with a two-conductor(unpowered) from the switch location. If it has a light also, then it needs ANOTHER 2-conductor (powered) from the switching locating. This is because the fan speed booster is a non-powered control wire from the fan itself, so the lighting is entirely separate. Edited to add: or for fan/light unit you can run a 3-wire to bring hot, neutral and light leg to the unit, plus a 2-wire for fan control.

http://ep.yimg.com/ty/cdn/rewilliams/whispergreenselectbrochure.pdf

They are good but allow some extra time for installation in your pricing.
 
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