Hi aclute,

I'm not a pro, but here's my two cent's worth as a person who recently bought a fixer upper with extensive water damage: you found a motor that will be easy to swap out, and you didn't mention finances being a key consideration, so...why not?

Moisture is the enemy, especially in the bathroom. Small amounts over a long period of time can do considerable damage before you can see it. Consider your picture window your proverbial canary in the coal mine. A little time and expense now vs. a possible problem later that could run into the tens of thousands down the road.

This is my second home with water damage. The first one was back in 1998 in Sacramento, in a house my now ex and I bought. I was out in the back yard while DH was in the shower and noticed a veritable river running down the outside of the house! We were lucky. We were able to successfully sue the home inspector, which I've been told is very, very hard to do, plus our new neighbor had a garage full of every tool known to humankind and was the best DIY-er I've ever known. Really lucky.

My current house I knew had water damage, and pretty much every other kind of damage, going in. I just didn't know how much. The home was previously owned by hoarders who were completely negligent and just didn't care that the house was falling down around them. That being said, I was able to pick up the house for almost nothing, and my daughter and I are rebuilding it from the ground up.

Anyway, I shudder to think what we're going to find when we pull up the tile in the bathroom and open up the walls. I'm putting in a combo light/fan/heater, and I'm going to ask the electrician to wire it so the light and fan are both turned on with the same switch. This is because I have a daughter who likes long hot baths and doesn't love having the fan running. So if she wants light, she's gonna get the fan too, ha! :-)

As I said, I'm not a contractor of any kind, just a person who has seen first-hand what moisture can do to a house over time. I ran the numbers too, and 80CFM is not adequate for your large bathroom; it doesn't matter what brand fan you have, an 80CFM can't handle that size room, and you have proof of that by measuring the humidity when you and your wife shower with the door open or closed, respectively. Further evidence is the window situation.

My advice, as a fellow homeowner who has lived through it before and who now has to likely spend in the neighborhood of $20,000 to fix water damage in my new house (throughout the house, not just the bathroom), is do it now.

I hoe this helps. :-)

Sincerely,

Debbie

Thanks! Money is not a factor in this decision, because the replacement motor is only like $100-$150.

I ask because it is obvious that 80CFM is undersized, but 110CFM also appears to be undersized as well, and is only a ~35% increase in capacity. Would even be worth the effort?

Interesting thread. I would just add that the CFM's may not tell the whole story. If you existing fan is not ducted properly, or if the legth of the ducts are too long/too mant turns, that could reduce the effective flow rate to below the stated CFM.

Good point. This is a first floor master. Duct is solid metal that travels up through a common wall to the attic and out the side of the house. Total run is about 25', with 2 90 degree turns. Duct in attic is wrapped insulation.

I have confirmed that it is exhausting to the outside (can see vent open up outside when fan is on).

This is a 15 year old fan unit and the manufacturer doesn't sell it anymore. From the user manual I can tell the 80 and 110 units use the same housing. Should be a straight forward replacement .

http://homeappliance.manualsonline.com/manuals/mfg/broan/s80u_1.html

This is would be a "hack" so not much I can rely on other than people's advice and trial and error.

From my experience the cost of the larger motor is way too high. Have you searched the net for one? Grainger supply used to carry such things at a much lower price. I bought a 110 cfm Broan squirrel cage fan for my home about 17 years ago. At that time the list price was about $140 but I got mine for much less at a local discount plumbing supplier.

Shipped, and one the way. Bought up eBay (new) for $90

Well, look at it like this: if you don't see significant improvement, you're only out ninety bucks and a little time. That does seem like a pretty long ways the air has to travel, and with two 90 degree turns, I worry that it might not be adequate. But I think it's worth the risk to try the "hack." Good luck, and let us know how it turns out! :-)

Day 1 of showers and there was no noticeable spike in humidity at all during or after my wife's turn. :D

One contributing factor might have been the old fan blades had a noticeable layer of gunk on them. I had seen it before, and tried wiping them down without success. I thought maybe it might have been some type of coating for soundproofing. Whoops! Once I got it down and started going at it, I found it to be coated.

So I don't know if it is the extra capacity, or the clean blades that is helping, but am not going to mess with anymore!

One benefit is that we use to set the timer for an hour -- I am thinking now we can reduce that down to 30 minutes.

If you can afford to do so a larger capacity fan will benefit you by removing more moisture out of the room quicker. However it Sounds like you should dedicate an entire room just for the growroom. It is too difficult to control an area when it is being used on a daily basis especially a bathroom area.

Grow room? I am not sure what you are taking about.

Unfortuently I cannot do a larger fan because I am limited to a 4" duct.

Hey there! I'm happy to see you did it and it worked! I'm with you; if it's doing the job, I'd leave it alone. Happy showering! :-)