On Mon, 4 Jan 2010 01:29:42 -0600, "William Wixon"
wrote:

is this possible? plumbing together two 20 lb. propane tanks? i've got a
propane heater in my workshop, it draws too much propane for one 20 lb.
tank, freezes the propane. i was wondering if i plumbed two together if i'd
be able to get enough gas to run the heater. is this stupid? do people do
this? was wondering if they were plumbed together should it be before or
after the regulator(s)? wondering if that's even possible, to have two
separate regulators on two separate tanks running one heater. i don't want
to get a larger tank, i've collected about 6 - 20 lb. tanks, i don't want to
have to buy or rent a larger tank. (100 lb.?) i usually use propane for
quick heat, warm up the shop until i get the wood stove fired up and making
heat, then i turn off the propane heater so i'm not running propane
continuously, maybe 1/2 hour.

It's very possible - the simplest way is to get one of the Double
Check-Valve Tees off an old travel trailer, then remove the POL
fitting from your existing propane hose. Attach the OUT port of the
tee to the Heater hose, then attach the two short whip hoses to the
two IN ports of the tee.

The check valves are Very Critical, if you can't find the purpose
built piece (that they stopped using widely in the 1970's for the
automatic units below) get a regular tee and two spring-loaded ball
check valves rated for 300 PSI.

The check valves ensure that even if some dimbulb disconnects one
tank hose with the other one pressurized, you won't have a huge gas
leak out the whip hose POL fitting.

The hot ticket is an automatic-changeover regulator like this one from
Emerson Fisher
http://www.fisherregulators.com/products/literature/lp/R962/

Or this one from Taiwan somewhere...
http://www.tractorsupply.com/home-improvement/home-improvement/propane-heaters-accessories/propane-regulators/mr-heater-two-stage-auto-changeover-propane-regulator-2136085

Or the Marshall 250 - nice because it's a lever to show which tank is
the 'preferred' and the red flag shows transfer.
http://www.propaneproducts.com/Merch...ode=Regulators

If nothing leaks, the check valves and/or the automatic changeover
valves let you change tanks on the fly as it runs on the reserve with
no problems - but you want to make sure there are no leaks BEFORE you
try it with a lit appliance anywhere close.

The automatic valves drop a red flag in a window (some more visible
than others) when they have switched to the reserve tank, to indicate
that you need to change the empty. Once you change tanks you have to
follow the instructions to reset the flag, so it pops again when the
second tank runs dry and switches back to the first.

-- Bruce --