Venting Bathroom Fan problems

[ffemt]

As the title says I'm having a condesation problem need help. I had 4" flexible dryer vent hose that sag and held water what I replaced it with is at the fan is shuttters to close the out side air out a flexible 90 coming out of fan to rigid flex 4" to a regalur square roof vent. Sometimes I have water dripping into the tub from fan but not always, doesn't matter if shower was used or not.This is the first house I owned out of four with this problem also the first that wasn't vented to the soffit Is this and insulation problem around the fan or a down draft problem from the always open roof vent.


Thanks for any help

Geoff


X2 both baths or call 847 417 4018

 

[scottiking]

I would insulate all the exhaust pipe and around fan, and make sure the flap is closing on the fan and the roof vent so cold air wont blow back in which will cause condesation due to cold air hitting the warm inside the exhaust pipe!
Sometimes if the flap on the roof side of the vent is facing west or northwest the wind will blow the flapper open!
Just dont let the exhaust blow into the attic either because that can cause a big mold issue down the line!
Good luck

Scottiking OUT

 

[anonomoose]

Re-route the vent to the soffit, the wind won't "force" cold air back down the pipe and cause condensation.

Bath has high humidity levels and the combination will cause condensation to occur all along the vent hose and including the exit. So expect it....insulate the hose all the way to the soffit and make sure that the hose is running "down hill" to the soffit. If you use the fan a bunch (if it turns on with the light) then you probably could get away with a long slow belly in the hose to the vent where water from condensation will collect and eventually evaporate....unless you have teenagers who take long hot showers twice a day when you can actually FILL the hose up with moisture....so expect that too!

 

[favoritos]

Run a straight pipe to the roof and insulate the pipe. Put a timer on the fan and run it long enough after using the shower to get the moisture out of the room. Simple rule is to run the fan 20 minutes for a 10 minute shower.
Put a good flapper vent at the exit location.
Do not use flex hose. It has issues with condensation on the ridges and that is what is falling back down the tube. Do not run to the soffit. Most homes use that area as the inflow to the attic.

 

[scottiking]

FYI- he said it gets condensation even if with no showering!

Scottiking OUT

 

[yamahauler]

If the pipe vents directly out the roof, can you put a 90 degree on the end so the outside air would have to travel up and around.
I would recommend the insulation and would run the black pvc pipe.

I don't know if mine is insulated but when it is really windy above 20mph I can hear the flapper in the exhaust fan flapping but have never had
moisture come out of the fan.

 

[dereks2623]

Insulated pipe is the way to go as it was posted earlier you have the warm moist air in the winter from your bathroom (weather the fan is on or not) exhausting out in the winter into a cold attic creating condensation on the inside of the pipe, and in the summer months its the same with cooler air going out into a hot attic. It does not matter if you have flex pipe or smooth metal piping it will all do the same untill you insulate it. With the fact that you have condensation issues all the time its because your home is probably fairly tight. If you have condensation on your windows its not because your windows are bad its because no matter how much money a person spends on the windows in their home it will always be the weakest point in a home when it comes to an r-value standpoint. When you have warm moist air in the winter (because your home is all shut up, meaning no open windows or doors opening very often) hitting the cold surface of the window and it drops the dew point and creates the condensation. Best thing you could do to remedy that problem is either spend lots of money on a HRV or ERV system which requires a fair deal of maintinence or install a timer on your bathfan that every time you turn it on it runs for either a half hour to an hour after each time you switch it off. It will draw in fresh air through all of the small cracks and what not that are still in your home and help with reducing the condensation issues in your home and also bring in the fresh air that brings the humidity level to the range it should be in a home (between 40 and 60 percent) were there is a less chance for any type of mold or mildew to build up in the top corners of ceilings. Also do not vent it out of the soffit unless you have unvented soffit. If its vented soffit every time you crank on your bath fan it will dump all of the high moisture air out at your soffit and depending on the wind it could take it directly back up into your attic hitting the roof sheeting underneath and start rotting your roof sheeting out. If possible take it to a gable end either on the south or east side but if not an option buy a roof vent with its own flapper and again install it away from the direct wind side use insulated pipe or wrap with duct wrap and install the timer on your switch and it should take care of a big majority of your problems.

 

[IceJam]

Was a Insulation Contractor for 18yrs and this is 100% correct !!

Re-route the vent to the soffit, the wind won't "force" cold air back down the pipe and cause condensation.

Bath has high humidity levels and the combination will cause condensation to occur all along the vent hose and including the exit. So expect it....insulate the hose all the way to the soffit and make sure that the hose is running "down hill" to the soffit. If you use the fan a bunch (if it turns on with the light) then you probably could get away with a long slow belly in the hose to the vent where water from condensation will collect and eventually evaporate....unless you have teenagers who take long hot showers twice a day when you can actually FILL the hose up with moisture....so expect that too!

 

[dereks2623]

i highly recomend if at all possible do not take to soffit if vented soffit. If it is solid soffit this will work to a degree. While it is easier to get even a down hill slope to your soffit if you are dealing with pre existing conditions and if your home is a ranch with a 4-12 pitch its hard for even the smallest of workers to get squeezed out to the edge of the attic and add possibly 8 to 10 inches of either cellulose or blown fiberglass and it makes it even worse. For the state of wisconsin's weatherization program which is guided by ASHRAE's 62.2 standard for ventilation we are required to only vent out of soffit if its last possible approach. Another great way to maximize the cfm from your bath fan is to take it from 4" to 6" with a simple adapter, run 6" insulated flex to the gable reduce back down to 4" and vent to exterior with a louvered 4" dryer vent. I have been to numerous conferences and other seminars where this is a proven method to get the maximum amount of cfm out of your bath fan. If you put on 4" white flex the whole way and have any bends or turns at all you can almost gaurentee that you will reduce the cfm of your fan by three eighths to half of the rating from the factory. If you do it the way i explained you can honestly darn near tie the six inch flex in a knot (this was actually demonstrated to me once) and even with reducing it back down to 4" at the termination you will only lose at the very most ten cfm. You can test this either with a anemometer or a pressure flow meter from the minneapolis blower door company. Another idea is have an energy audit done on your home. Im willing to bet that with the conditions that you noted that your home is tight enough and the occupancy count is high enough that you could use cont ventilation to control the high moisture problem. Contact your local utility company and see if they offer a discounted rate for energy audits. Our local utility company (excell energy) is offering them to home owners for 35 bucks per person. A certified energy auditor will come to your home and do a full home performance test and inform you of the best way to tighten your home up safely without causing any potential health and safety problems from back drafting water heaters and other various home related problems. I dont work for any utility companys but i work for a local weatherization agency and have had extensive training in these fields.

 

[ffemt]

Wow thanks for all the responses Have a lot of thinking to do here, yes we have 6 occupants so alot of showers but they are usually timed. House has been always humid in winter moisture on windows, we always run a dehumidafier in the basement near furnace f/a house is 5yrs old offset ranch with three roof lines. I think the biggest problem is the standard square roof vent with no luovers out the east side of roof getting a down draft on windy days.To go out the gable end would be along run. I'm not running flex hose right know I thru that in the garbage fill with water and mildew, I have rigid but flexible pipe to the roof vent. The house has a ridge vent on every roof and all soffits are vents so it make sense not to dump the humid air there. I guess dryer vents to the gable will solve the problem would be a 20 ft run x 2 . Thanks again Geoff

 

[favoritos]

That standard roof vent without a flap may be a major factor. Condensation is where cold air meets warm. No flap means that you either have warm air trickling out or cold air sliding down into the home. Try replacing that vent on the roof before cutting new holes on the outside.

The humidity inside the home is always something to keep a watch on over time. Condensation on windows will shorten their lifespan considerably. Does the home have any type of ventilator system? I have seen awesome HRV systems that never get used because the homeowner does not know the benefits.