I took specs from the Propex on-line brochures and
my Carver P4 manual and various on-line conversion sites
and assembled the following, which might be of interest
to anyone with a furnace or considering one.  This page
is also on-line at:
http://jones.colorado.edu/jones/PropaneFacts.html
For the curious, pictures of a Carver installation are at:
http://www.sittser.com/P4Pictures.htm   The Propex 1800
fits very similarly, I believe.
[Anyone noticing errors, please p-mail me.]

                        Richard A Jones
                        Boulder, Colorado
-----------------------------------------------------

        Propane Factiods
                                6 Mar 2006 RAJ

        US: 11" water = 0.03974 psi
        British: 37 mbar (= 15" water [14.86"] = 0.555 psi)

                        Propex   Carver   Carver  Propex
                        1800     P4 high  P4 low  2800

 gram/hr propane in     128      175      88      225
 kW propane in                   2.4      1.4
   = gal/hr             0.0664   0.09099  0.04576 0.11675
   hr/2.5 gal tank      37.6     27.4     54.6    21.4

 kW out                 1.6      2.2      1.2     2.8
 BTU out                5461     7260     4095    9556

 current consumpt (A)   1.2      2.5 max  1.2 max 1.9

        misc:

        1 gram = 0.00220462 lbs
        1 BTU = 0.0002930722 kW-hr
        1 mbar = 0.4165" water
        1" water = 2.4897 mbar
        1 mbar = 0.015 pse
        1" water = 0.03602 psi
        1 psi = 27.7612" water
        1 gal = 91500 btu = 4.23 kbs
        1 gal = 36 cu ft
        lbs / 4.23 = gal
        gram x 0.000519957 = gal