On Sat, 11 Dec 2004 13:35:42 -0800, Loren Amelang
vaguely proposed a theory
.......and in reply I say!:

remove ns from my header address to reply via email


Pure methane (the major component of NG) has a stoichiometric air-gas
ratio of 9.53 to 1 on a volume basis (the weight ratio is 17.2 to 1).
For air-propane, you need 23.82 to 1 by volume, or 15.25 to 1 by
weight.
http://www.process-heating.com/CDA/ArticleInformation/Energy_Notes_Item/0,3271,84749,00.html

The BTU/cuft for NG is 1012, and for propane is 2516, so you need only
40% as much propane by volume for the same output. Taking 40% * 23.82
/ 9.53 gives almost exactly 1 - theoretically the same amount of air
through the burner, with 40% as much propane, should give the same
output.
http://www.altenergy.com/propaned.htm

makes sense, and it saved me the trouble....G

Not only have I never reached equal heat output converting from NG to
propane, I've usually run into serious usability issues that forced me
to back off to even lower than maximum possible output.

Anybody out there understand why?

I wonder if it's because propane is _not_ delivered at much higher
pressures. BBQs etc have that regulator that really throttles things
down. You get a propane heating torh that comes straight off the
bottle and it has no trouble with burnback or blowout, and really
belts out the heat. Also I have a propane-based instant gas water
system, and it roars with gas and produces enormous amounts of heat.
Again at a higher pressure, largely letting the orifice do the work.
---
Only worry about the things you can control.

Then you have stuff all to worry about!