wrote in message ...
On Wed, 11 Dec 2013 21:11:09 -0600, "Irreverent Maximus"
wrote:


"Danny D." wrote in message ...
Looking up why a propane furnace needs a lockout timer,
I find that they want the gas to be cleared from the
pipes *before* igniting the pilot (hence why the lockout
timer is a normally open switch).

It seems to say so, on the last sentence, of this document:
http://xpedio.carrier.com/idc/groups.../58se-11si.pdf
http://xpedio.carrier.com/idc/groups...0394dp40-a.pdf


Actually, the timer times open, meaning that it activates when the pilot fails
to light. This prevents the pilot valve from filling the combustion chamber with
propane and subsequent ignition via the pilot igniter. The timer has a manual reset.
Something else for you to keep track of in case the unit does not start.

This timer is only for the use with LPG (propane). One of the reasons I disagree with
the installation manual's statement to discard the old parts. It would be preferable to
keep the old in a bag, with instructions, so that the unit may easily be converted back
to natural gas. In your case this might not be a big deal, but I know for certain that
if I had the chance to switch to NG, I would do it in a heartbeat. Cheaper to operate.

Oh, tell the wife that she is not a thermostat. Let the thermostat do its job. That and
to make you a sandwich and bring you a beer. :-)
Having the timer on for Natural Gas would most likely not be an
issue - just not REQUIRED, like it is for Propane.

True, but one still needs the orifices. Swap out the orifices plus MGV spring, then swap a
few wires and the system is 100% NG. The wiring takes about 2 minutes (if one is slow).
Some tweaking on the MGV output will be necessary, too...