dryer vent question

[phish]

my new dryer vent was installed down into my crawl space approx. 12" then a 90, then about 5' horizontal to the outside termination. problem was it was to low to meet the 12" height requirement from the ground at the termination. called the installer back, and he just went vertical again for about 6" then back out. so my question is before i call for another inspection..is it ok to vent down then horizontal, then back up? it creates a u type shape. is it permissable since it only goes back up a short distance?

thanks

[marter]

I dont have my code book handy but I would think that would be a violation, that would be creating a lint trap a fire hazard. could be wrong though

[hvamimi]

Believe that Marter is right. That would get full of lint quickly and than their would be no vent.

[phish]

this is what i also assumed, which is why i asked. i didnt want to tell someone who's supposed to know what their doing how to do their job. i wanted some backup input before i call them back out. i guess my next situation would be how to run the vent...right next to the dryer is a slop sink, then the outside wall the installer had suggested notching the slopsink cabinet, and just making a straight termination to the outside, but i was leary about that also. seems the easiest way. is it acceptable? how hot do those get? is there a clearance to combustibles with a dryer vent?

i'll be calling the installer today to schedule an appt to remedy

any help is appreciated...

[gevans]

The straightest shot, shortest distance, and least number of bends is always the best.
The pipe gets hot, but not hot enough to cause a fire (unless your dryer has a major malfunction).
From what you describe, I think I'd run through the slop sink cabinet. And use hard pipe, not flex. Flex should only be used to attach the dryer to the pipe.

[hvactech1968]

International Mechanical Codes 2006 (IMC) Codes for Clothes Dryers Section 504

504.3 Cleanout. Each vertical riser shall be provided with a means for a cleanout.

504.6 Domestic clothes dryer ducts. Exhaust ducts for domstic clothes dryers shall be constructed of metal and shall have a smooth interior finish. (no screws section 504.4) The exhaust shall be a minimum nominal size of 4 inches in diameter.

504.6.1 Maximum length. The maximum length of a clothes dryer exhaust shall not exceed 25 feet from the dryer location to the outlet terminal. The maximum length of the duct shall be reduced 2 ½ feet for each 45-degree bend and 5 feet for each 90-degree bend. The maximum length of the exhaust duct does not include the transition duct.


I am neither your contractor nor your inspector. I will let you interpret the rules.

[phish]

the installer was quick to call back, since he knew i was waiting on an inspection..the image shows whats proposed..since the cabinet has no back, it will be notched with a 3 sided box on the inside to prevent anyone acidentally putting something against the hot pipe..it will now be a 90 down from the dryer (stackable) short 12" piece to another 90 then horizontal about 4' to the outside. think it will be fine?

[cem-bsee]

damm shame that the IMC is not a preformance code! --
as quoted, it is quite restrictive!-

[dad211]

no it cant go down then up. good for you for having it inspected