Dryer Vent Attached to Bathroom Exhaust Vent

[Rick Milano]

Just thought I would share this with you guys, since I just posted my intro after all these years, lets make it two posts. The vent on the right in the pic is the clothes dryer vent attached to the bathroom exhaust vent and taped heavily of course. Sure I had all kinds of things to explain to the client about why this was not ideal. First time I have seen this configuration and I searched all over the internet just for some more clear language but really nothing about this exact situation, not surprising. Anyway I didnt have a problem explaining it but I often look for more info on situations I have never seen just to help ensure clear explanations in my reports. Your thoughts would be interesting to read.

[Dan Hagman]

Dryer exhaust systems shall be independent of all other systems and need to terminate to the exterior. The duct needs to be 4" hard pipe with no screws and have a smooth interior finish, the maximum length is 25 feet, deduct 2 1/2 feet for each 45 degree elbow and 5 feet for each 90 degree elbow. It needs to be disconnected from the bathroom exhaust vent.

[Jack Feldmann]

Dryer vents can be longer - much longer if dryer manf. says so.

[Jerry Peck]

Dryer vents can be longer - much longer if dryer manf. says so.

Yes, but ... :)

From the IRC:
- M1502.4.6 Length identification.
- - Where the exhaust duct equivalent length exceeds 35 feet (10 668 mm), the equivalent length of the exhaust duct shall be identified on a permanent label or tag. The label or tag shall be located within 6 feet (1829 mm) of the exhaust duct connection.

[Jack Feldmann]

Yes, but ... :)

From the IRC:
- M1502.4.6 Length identification.
- - Where the exhaust duct equivalent length exceeds 35 feet (10 668 mm), the equivalent length of the exhaust duct shall be identified on a permanent label or tag. The label or tag shall be located within 6 feet (1829 mm) of the exhaust duct connection.

Like said, they can be longer than 25 feet.

[Jerry Peck]

Like said, they can be longer than 25 feet.

And like I said ... when permanently labeled with the length of the duct.

If the length is not labeled, then no extra length is permitted, which makes the answer a 'yes, but' answer ...

... longer ducts are allowed, but ...

... but the longer length is required to have a permanent label stating the longer length.

Not all simple answers are simply yes and no, some are 'yes, if', 'yes, but', or 'no, unless' ... the answer to the question/statement you replied to was one of those 'yes, but' answers - you provided the first part of the answer, I provided second part of the answer.

[Jack Feldmann]

Of course Jerry....I'll let you have the last word since its so important to you. I didn't list all of the exceptions, since I was just making the point that there are exceptions.

[Jerry Peck]

Of course Jerry....I'll let you have the last word since its so important to you. I didn't list all of the exceptions, since I was just making the point that there are exceptions.

Jack,

I don't know what has gotten into you lately, seems as if you have decided that if you can't do it your way you don't like doing it.

Dan made a statement, YOU made a correction, I then added information to your correction and essentially made a correction to your correction ... but that was unacceptable to you.

If you correct someone, make sure your correction is correct, otherwise expect to be corrected ... JUST LIKE YOU DID to Dan's statement. It is simple and why this board works - we all like to have the correct information on the topic being discussed - not sure why it bothers you to have the correct information provided ... Dan was correct in his way just as much as you were correct in your way, but you did not leave Dan's comment 'uncorrected' - yet you wanted your comment to be 'uncorrected'.

I guess we all are supposed to look at the posts and go 'Oh, Jack Feldmann posted that ... we are not supposed to comment any further.'???

[Tom Rees]

The clothes dryer and bathroom exhaust fan are not allowed to share a duct. The bathroom fan forces air from the bathroom into the dryer exhaust duct creating a back pressure in a connected dryer. The dryer can also force air and lint into the bathroom vent instead of to exterior.

[Dan Hagman]

Thanks for the added information Jack and Jerry! Just another thought, when I was installing HVAC and dryer vents in new construction the City Municipal Mechanical inspector would not allow over 25 feet including the elbow subtraction. If it was longer he would say to shorten it and maybe there was no way it could be done and I would ask him to show me a way and I will do it, and after he looked at it he would just walk away and let it go. The problem I had with the longer runs is that there was no dryer around during the rough in and I didn't know what dryer was going to be purchased either by the builder or the buyer so they made us stick to the 25 feet rule with no other information that was available. That's all I was saying, now if you have the information from the manufacturer then you would know how far you can go. Good information, thanks for the reminder!

[Dave Rose]

Thanks for the added information Jack and Jerry! Just another thought, when I was installing HVAC and dryer vents in new construction the City Municipal Mechanical inspector would not allow over 25 feet including the elbow subtraction. If it was longer he would say to shorten it and maybe there was no way it could be done and I would ask him to show me a way and I will do it, and after he looked at it he would just walk away and let it go. The problem I had with the longer runs is that there was no dryer around during the rough in and I didn't know what dryer was going to be purchased either by the builder or the buyer so they made us stick to the 25 feet rule with no other information that was available. That's all I was saying, now if you have the information from the manufacturer then you would know how far you can go. Good information, thanks for the reminder!Could you not use a helper fan if longer than 25'? (or I think it's 35 feet today...change recently)