Yeung Fun Ho wrote:
Can anyone recommend any cheapo DIY ideas on how to exhaust heat from
an attic in a house?



unlike some of the folks here, who are forgetting a very important point,
let me remind you of something:

many places in the USA have high RADON levels
(RADON, a colorless, odorless gas, is the 2nd leading cause of lung cancer,
after smoking)

many of the solutions that are typically presented in this group involve
exhausting attic heat via a fan, turbine, etc.

True, but many places have no problem with radon.
Besides, the solution is generally simple and
inexpensive. (Of course there are "fixers" who
will insist that very expensive solutions are
necessary). Before anyone gets excited, check
with local health or other organizations for
radon in the local soils.


most of these are "negative pressure" solutions, i.e. they suck air out in
order to exhaust the unwanted heat

this will cause RADON to be sucked IN to your home from the ground

Almost any attic ventilation solution requires air
inlets and outlets. A fan that blows out requires
air inlets, either openings in the end gables or
openings in the soffits. As a result, very little
negative pressure will be developed. In any case,
negative pressure in the attic won't have any
effect on Radon in the house unless the attic is
tied to the rest of the house, the basement, or
the crawlspace and that isn't the case in most
houses (it may be the case with a whole house
fan). For radon to be a problem, radon has to
infiltrate the house from the soil. That may
occur from a basement or crawl space, but not from
an attic.