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dpb[_3_]

On 2/23/2020 2:28 PM, wrote:
....

I have never had a gas dryer but the more I read about them the more
it sounds like they just start a fire, blow air across it and exhaust
through the drum (No real heat exchanger at all). Again Yikes!
I hope you have plenty of makeup air.

Well, in the most basic, yes, but they have a combustion chamber and air
is blown over/around it, not just directly onto the flame.

As for makeup air, a clothes dryer is in the 20-25 kBtu/hr while an old
50% natural draft furnace would typically be 100-150 kBtu/hr so it's
only a fourth or so of the combustion air required.

In looking, I was surprised to learn the tumble dryer as we know it is
really relatively recent -- it appears the first economical design
didn't become commercial until 1938; I'd've thunk would have been at
least 20 year before that.

But, they've been around now long enough there's ample evidence there's
no significant health consequences in design as are; did find that CPSC
did study in 1990s-2000 range that said in 1996 that were 15,000
dryer-related fires. But, also noted that there were an average of some
3-4 million electric and another 1-1.3 million gas units sold/year and
an estimate of about 73 million dryers in use. So, 15,500/73,000,000
isn't a terribly high failure rate.

Did note that of a small sample (79 incidents total) investigated that
about half the fires were either in the ducting or the lint trap w/ no
real pattern of any of the rest. Of those, about 50:50 whether the
owner would fess up as to that didn't regularly clean the trap/inspect
the ducting.

Numbers were somewhat higher of ~2:1 gas vs electric where there was
fire for the type of dryer reported (70 of the 79; 9 unknown type).
Didn't report on the 15,000 incidents by type.

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