On 12/17/2011 10:38 PM, jerry4 wrote:
On Sat, 17 Dec 2011 10:00:22 -0500, Kickin' Ass and Takin' Names wrote:

On Fri, 16 Dec 2011 18:20:26 -0500, "
wrote:



Also -- how does your system dispose of condensate? Is there a
condensate pump? If it's not working, the system will start up then
shut down when it sense the condensate pump is not working.

This has been the prob with my Mom's gas furnace... the condensate
reservoir fills up and trips the float switch because the condensate pump
isn't working (or the drain line is frozen in my case). the fans run but
no gas, etc

That would be the first thing to check. If not that, then I
would check the induced fan blower system that exhausts the
hot gasses.
You would want to make sure the flue pipe is clear, and
also the little tiny hole that is in the blower housing,
which is inside the nipple where the little usually rubber
hose connects. Many times that little hole will become
plugged and the pressure switch will fail to operate.
You can jump the float switch for a quick test.
You can also jump the pressure switch for a quick test,
but you have to start the furnace cycle first, let the exhaust
fan start running, and then jump the switch.
If you jump the pressure switch first, and then try to cycle the
furnace, it will see it as a bad pressure switch, and it will not
operate.
But in this case, the condensate reservoir is the more likely
culprit. That's a fairly common problem with those.