"My furnace only has a 5" bore a 6" exhaust would not be possible
unless you are talking 6 square inch, which is doable."
In that case, you won't ever turn the 3/4" up far enough to need the full
exhaust size so don't worry about it. In your case a smaller exhaust is
> If 6" is needed for a 3/4 burner (got your design from Dan), would a
> 1/2 inch work just fine for my small 5" bore. What is the
> approximate formula to relate burner size to exhaust port?
That depends on the burner type, effectiveness, and gas pressure you plan to
run it at.
> Dan said that 4" long x 1/2 diameter set of inlets was needed for the
> burner, if I scale back to 1/2 inch burner would the length still be
> 4" or scaled down also (what ratio).
Scaled down to four intakes (air openings) 5/16" x 2 1/2"
> I was thinking about using the 3/16id by 5/16od brass tube from
> online metals to mount the tweeco tip since it would provide less
> constriction to air flow than the 3/8 od of standard brass gas
That's a fine plan, Tom. You should be able to run both internal MIG thread
and external pipe thread on that size (put the tube in a drill and spin it
under a file to prepare it for a 1/8" pipe thread die). Make sure the tube
length does not fall below 3" (not including the 1 1/2" long MIG tip). The
1/2" burner is probably a better choice for your furnace. You have done very
well with your questions up to this point. I will answer no more of them
here. If you need private help and are willing to sign a nondisclosure
agreement, then I will take this further--otherwise not.
> Michael Porter
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