The bathroom is small and the cfm required would be minimal, which will end up being 80 according to what most brands now sell.

House is tight, but I don't have an hrv/erv. I've heard a lot of people talking about panasonic's exhaust fans but I don't understand how they're any different than something I would pick up at a big box store.

What do you think?

Not all fans are the same.The cfm rating is the amount of air that the fan will exhaust at a specific static pressure.Fans are also rated in sones.The higher the sone rating the noisier the fan will be. Panasonic makes a great line of bathroom fan products.

Some brands of bathroom fans, including Panasonic, use ECM (electronically commutated motors) fans which appear to the be most efficient fan motors that are available.

Another gadget feature that is available on some Panasonic fans (and perhaps other brands) is an infrared sensor to automatically turn on the fans when they sense people. They will then turn off after a period of time that the user can set when they no longer sense people present. This is handy for guests visiting the bathroom, and for turning off the fan automatically after it has had time to clear steam from a shower.

As acwizard says, noise is an important specification for bathroom fans. I am happy with the relatively low noise of the Panasonic fans that I have.

I put Soler-Palau ducted fans into my attic space with a short insulated flex from the ceiling to the blower and from the blower to the gable end exhaust. Like it a lot and very quiet....only air movement noise.

Now when I visit other folks their fans really grate on me.

All the answers are well said. Noise and control of that fan for energy efficiency is where panasonic excels.

All the answers are well said. Noise and control of that fan for energy efficiency is where panasonic excels.

My area code allows one to NOT have a bathroom exhaust fan as long as you have an operable window in the bathroom. I might try and run the ERV return line from the bathroom but I have never run exhaust fans here in AZ and I have never experienced moisture issues. It's so dry out here that we sit at 25% indoor humidity levels even after taking a shower.

Similarly in dry Colorado, I use a bathroom exhaust fan (as well as the HRV) in the warm season, but just the HRV in the cool season. I don't even fog the mirror with a shower in this area. I add humidity via a whole-house humidifier to maintain an indoor humidity of 35%, which is automatically adjusted lower when the outdoor temperature is low. (It was 23% this morning when the outdoor temperature was 3 degF.)

Posted By Lee Dodge on 06 Jan 2013 10:07 AM
Similarly in dry Colorado, I use a bathroom exhaust fan (as well as the HRV) in the warm season, but just the HRV in the cool season. I don't even fog the mirror with a shower in this area. I add humidity via a whole-house humidifier to maintain an indoor humidity of 35%, which is automatically adjusted lower when the outdoor temperature is low. (It was 23% this morning when the outdoor temperature was 3 degF.)

I noticed that the 2012 IRC separates the dry climate(B), marine climate(C) and moist climate (A) zones and assigns them a separate sub-category. So there is a Zone 4 and then my area would be Zone 4B.

One could get away without a bathroom exhaust fan out here but in Georgia or the Midwest, not likely.

What do you think?

I would like one that pulls through the toilet for more effective control of odors.

Posted By jonr on 06 Jan 2013 11:01 PM
I would like one that pulls through the toilet for more effective control of odors.

An excellent point, jonr. I should have been more specific with my comments above. I have a separate "throne" room for the toilet, and a separate exhaust fan in the throne room. I always use that fan when that room is in use, and it is effective in getting rid of bad odors.

I have a separate larger room for the shower, tub, and wash basins, and a separate exhaust fan in that room mostly for exhausting the steam from the shower or tub. I use that exhaust fan more in the warm season for exhausting the moisture. Both rooms are served by the HRV since the duct system has separate inflow ducts for both rooms, and in the winter I mostly just use the HRV in the shower area to recirculate the moisture to the rest of the house and/or exhaust the moisture from the house.

So it is definitely nice to have an exhaust fan for exhausting bad odors, whether or not it is used to exhaust moisture from the bathroom.

Can one run ERV return ducts from the bathroom instead of a simple bathroom fan?

I think that is a recommended location for exhaust intakes. As the size of the bathroom increases, the fan capacity needed to service it goes up. HRVs/ERVs are fairly low volume systems and large bathrooms may need more than the ERV intake to service it depending on your expectations.

If you are not sure, now would be the time to install the additional exhaust only fan. I put mine in the toilet rooms. If the bathroom itself needs more exhausting than the ERV can deliver, you can open the door and pop on the fan for a few minutes. The electronic timer switches are ideal for this. Make sure you get the right timer. DO NOT put one in with a max time of an hour. That is completely unnecessary and wastes energy. Get one that tops out at 10 min or something.

I was told that if the indoor temps are 74F and the outdoor temps are 20F, the conditioned air coming through a HRV (70% efficiency) would equal 57F. That's cold air.

I can see why some people are apprehensive about installing mechanical HRV/ERV systems. Although the alternative is not any better, which is letting a house "leak air" through the walls or a tight home with no ventilation which would cause CO2 problems and air quality issues.

Posted By Lbear on 11 Jan 2013 04:27 PM
I was told that if the indoor temps are 74F and the outdoor temps are 20F, the conditioned air coming through a HRV (70% efficiency) would equal 57F. That's cold air.

I can see why some people are apprehensive about installing mechanical HRV/ERV systems. Although the alternative is not any better, which is letting a house "leak air" through the walls or a tight home with no ventilation which would cause CO2 problems and air quality issues. Comp

Comparing leaked air pulled in by an exhaust fan to fresh air brought in by an HRV, it takes about 3.2 times as much energy to heat the same mass of air from 20 F to 74 F as from 57 F to 74 F.  That is one of the attractions of HRV or ERV systems. 

With a ducted HRV or ERV system, the fresh air can be uniformly distributed in the house, as opposed to leaked air that could be just in some areas of the house.   

Count me in on the Panasonic fan club, too. I've been very happy with their performance and quiet operation. Good to hear the OP is doing the necessary cfm calculations. In my region it's the electrical contractor that installs the fans, and he told me they never even think about calculating and just put the smallest cheapest fan in every bathroom regardless of size. Good I was checking up on everything as I went along.

Panasonics seem to be the gold standard, whisper fits are a good value, higher end delta breeze are also good. Metal attached outlets on any fan versus the snap on plastic tend to indicate a better built fan with a better damper. Broan has a higher end line to compete with panasonic but i can get panasonics cheaper. Sometimes the deltas will be cheaper than panasonics. Built in humidistat overide is a feature I usually spec regardless of brand, nice insurance policy so homeowners dont need to mess with timers or turn off the fan too early.

While lower sones is quieter and generally a better fan, some people like a little fan noise to cover "bathroom" sounds depending on bath location. I've had people ask for a fan thats "not too quiet."
The drone of a fan beats total silence when there are 10 people at the kitchen island 8 feet from the half bath and you're on deck trying to ninja poop, in such cases the loud, cheap Broan from Menards is your friend.

Posted By greentree on 13 Sep 2016 07:24 AM
While lower sones is quieter and generally a better fan, some people like a little fan noise to cover "bathroom" sounds depending on bath location. I've had people ask for a fan thats "not too quiet."
The drone of a fan beats total silence when there are 10 people at the kitchen island 8 feet from the half bath and you're on deck trying to ninja poop, in such cases the loud, cheap Broan from Menards is your friend.

It's posts like this that keep me coming back to this forum. "Ninja Poop"... Love it. FWIW. I like the Panasonic fans as well.

I use a recessed LCD light with the fan built in above the can. It is also very quiet.