On Feb 16, 11:43*am, wrote:
On Feb 16, 10:02*am, "John Gilmer" wrote:





"John Grabowski" wrote in message

...

A few years ago a customer asked me about replacing her ancient hood which
had a duct going through the cabinet upwards. *I went up in the crawl
space above the stove to see the duct so I could figure on the proper
fittings. *I couldn't see it. *I went outside and looked on the roof for
the cap and could not find one. *So I asked her to cook something smoky
and turn on the exhaust fan. *When she did the smoke starting coming out
of the eaves. *Not through vent holes, but through gaps in the wood over a
wide area. *The duct through the cabinet was just poked through the
ceiling and stopped.

That's the way it used to be done.

The same for bathroom fans.

The primary reason to have it vented directly outside is to keep moisture
from condensing on the underside of the roof. * That's the potential of the
"downside." * In most climates, most of the time, it's a non-problem.

Most of the grease should be stopped by those metal mech "filters" which can
be cleaned in a dishwasher (somewhat, anyway).

Needless to say after about 30 years it was ugly up there. *Thank goodness
she never had a fire.

Unlikely. * Even in busy restaurants, such fires are rare.

The hood vent piping isn't installed like a flue; it often is directly
against combustible surfaces. * *If a stove fire gets out of control to the
point where the vent is hot enough to damage your 4" alluminum dryer vent
material, you have other problems.

The "flex vent (metal)" shouldn't be used mainly because it picks up crap
from the air flowing through. * *Sections of galvanized vent are dirt cheap
and are better for longer runs.

As a plumber and someone who doe's this for a living to code , please
consult the fire dept or your dept which handles code in your area .
Never use flexable alum pipe it is for dryers and not for stove fans ,
should not even be used there.
* * * Always use solid pipe as it last much better in a fire ,
flexable is for lazy not good work . * Restraunts usally will have
fire supression in the hood here they have to and they have to clean
more often hence less fires.- Hide quoted text -

- Show quoted text -

The hood vent piping isn't installed like a flue; it often is
directly
against combustible surfaces. If a stove fire gets out of control
to the
point where the vent is hot enough to damage your 4" alluminum dryer
vent
material, you have other problems

Yes you do consult the fool that did this install , your fiberglass
insulation takes more heat then the flexable dryer duct to melt and
hence is allowed to be around your galvanized pipe or vent . Still
new code calls for the vent to go down and across basement and out as
it stops attic fires . here the pratice of attic vents are on there
way out .