My 12 year old Keeprite furnace is heating the place OK but its cycling
without firing up intermittently. Sorry for the non-technical
description but here goes: when I listen to it fire up normally, I hear
a click followed by the flue fan (draft inducer) motor coming on and
then the gas ignition and heat. But recently, it has started doing all
of these without the gas ignition and heat. It sounds like its trying
to fire up but failing for soem reason. Anyone got any suggestions
before I call in a tech.

Thanks.

Jimbo

I had the same happen with a Sears induced draft gas furnace. The flue
blower runs and runs and runs but no gas and no heat.

The problem is the safety switch that detects the flue draft pressure is
stuck OFF and so prevents the gas valve from opening.

This device has two hoses attached to it that go to the flue blower and
two wires. You may be able to TEMPORARILY by-pass it to have heat now.
Switch the furnace power OFF, disconnect the wires from the safety
switch and jump them.

Order a replacement - it's there for a good reason.

On 12 Dec 2005 11:23:45 -0800, "Jimbo" wrote:

My 12 year old Keeprite furnace is heating the place OK but its cycling
without firing up intermittently. Sorry for the non-technical
description but here goes: when I listen to it fire up normally, I hear
a click followed by the flue fan (draft inducer) motor coming on and
then the gas ignition and heat. But recently, it has started doing all
of these without the gas ignition and heat. It sounds like its trying
to fire up but failing for soem reason. Anyone got any suggestions
before I call in a tech.

Thanks.

Jimbo

Yes,
Get a tech before you get suggestions. We cant see it from here.
Bubba

On Mon, 12 Dec 2005 17:42:02 -0800, "T.G. Lambach"
wrote:

I had the same happen with a Sears induced draft gas furnace. The flue
blower runs and runs and runs but no gas and no heat.

The problem is the safety switch that detects the flue draft pressure is
stuck OFF and so prevents the gas valve from opening.

This device has two hoses attached to it that go to the flue blower and
two wires. You may be able to TEMPORARILY by-pass it to have heat now.
Switch the furnace power OFF, disconnect the wires from the safety
switch and jump them.

Order a replacement - it's there for a good reason.

Bypass a draft pressure switch? TG, you are a ****in idiot. Yeah it
might get him heat and it might also get him dead. The pressure switch
could be doing its job by letting you know that the furnace has a big
hole in the heat exchanger. Would you like me to tell you about the
one I found today with a hole in the secondary big enough to put my
fist in? It was running when I got there. Some idiot told him how to
jump the pressure switchWas it you? 1000 ppm in the flue. Was it you?
Bubba

T.G. Lambach wrote:

I had the same happen with a Sears induced draft gas furnace. The flue
blower runs and runs and runs but no gas and no heat.

The problem is the safety switch that detects the flue draft pressure is
stuck OFF and so prevents the gas valve from opening.

This device has two hoses attached to it that go to the flue blower and
two wires. You may be able to TEMPORARILY by-pass it to have heat now.
Switch the furnace power OFF, disconnect the wires from the safety
switch and jump them.

Order a replacement - it's there for a good reason.

Because a safety is there for a good reason it's best not to by-pass it.
Never ever bypass a safety unless you're a qualified tech
troubleshooting the system. Even so a volt/ohmeter is the preferable
test for open limits and safeties when that option is available. Nobody
under any circumstance should ever leave a furnace running with safeties
jumped.

BTW, it's most likely not an open safety or limit given the OP's
description of his observations. It is likely an ignition failure
problem, but then we can't see it from here, so it could be that the gas
has been shut off, the gas valve is shorted or open, or any of a hundred
other things.

hvacrmedic

"T.G. Lambach" wrote in message
...
I had the same happen with a Sears induced draft gas furnace. The flue
blower runs and runs and runs but no gas and no heat.

The problem is the safety switch that detects the flue draft pressure is
stuck OFF and so prevents the gas valve from opening.

This device has two hoses attached to it that go to the flue blower and
two wires. You may be able to TEMPORARILY by-pass it to have heat now.
Switch the furnace power OFF, disconnect the wires from the safety switch
and jump them.


You can see that from where you sit?
Man, I have a job for you....seriously...couple of hundred an hour, if you
are that good...just pack up, and MAKE SURE YOU BRING YOUR CRYSTAL BALL WITH
YOU!!!


Order a replacement - it's there for a good reason.

Yea,....so is proper troublshooting advice, not that any was given.

T.G. Lambach wrote:

I had the same happen with a Sears induced draft gas furnace. The flue
blower runs and runs and runs but no gas and no heat.

The problem is the safety switch that detects the flue draft pressure is
stuck OFF and so prevents the gas valve from opening.

This device has two hoses attached to it that go to the flue blower and
two wires. You may be able to TEMPORARILY by-pass it to have heat now.
Switch the furnace power OFF, disconnect the wires from the safety
switch and jump them.

Order a replacement - it's there for a good reason.

Because a safety is there for a good reason it's best not to by-pass it.
Never ever bypass a safety unless you're a qualified tech
troubleshooting the system. Even so a volt/ohmeter is the preferable
test for open limits and safeties when that option is available. Nobody
under any circumstance should ever leave a furnace running with safeties
jumped.

BTW, it's most likely not an open safety or limit given the OP's
description of his observations. It is likely an ignition failure
problem, but then we can't see it from here, so it could be that the gas
has been shut off, the gas valve is shorted or open, or any of a hundred
other things.

hvacrmedic

Boys, please. Thanks for the suggestions but let me be clear, I'm not
looking to replace a tech by posting on here. My hope was that someone
could simply suggest how big an issue this is before I call in the
tech. TG's suggestion of checking the safety switch is fine. In fact
he did very clearly state *TEMPORARILY* in his post. As for the idea
to get a tech before suggestions, I've been burned that way before.
Nowadays I like to have some clue before handing over that blank
cheque/check If anyone can recommend an honest tech in Toronto, I'd
be happy to give him/her a call.

Jimbo wrote:

Boys, please. Thanks for the suggestions but let me be clear, I'm not
looking to replace a tech by posting on here. My hope was that someone
could simply suggest how big an issue this is before I call in the
tech. TG's suggestion of checking the safety switch is fine. In fact
he did very clearly state *TEMPORARILY* in his post.

We know what he said, apparently you don't yet.

hvacrmedic


As for the idea
to get a tech before suggestions, I've been burned that way before.
Nowadays I like to have some clue before handing over that blank
cheque/check If anyone can recommend an honest tech in Toronto, I'd
be happy to give him/her a call.

So, RP, is there any additional information I can offer or get that
might help someone help me analyse the problem. I'm not trying to put
anyone out of a job - just trying to gain a little knowledge.

Thanks in anticipation.

Jim

Jimbo wrote:

So, RP, is there any additional information I can offer or get that
might help someone help me analyse the problem. I'm not trying to put
anyone out of a job - just trying to gain a little knowledge.

Thanks in anticipation.

If you had read my previous post you would have found plenty to work
with without me actually telling you point blank what the problem is.
With a few more fill in the blanks I could probably do just that with a
comfortable margin of error. Hot surface ignitor or spark ignition?
Gas bill paid up? Smell gas during this sequence?

hvacrmedic

On Friday evening, I shut everything off, and spent 20/30 minutes
cleaning every surface I could easily access. Also, I checked all
connectors and contacts. Afterwards, I vacuumed all debris and
switched everything back on. For now, everything seems to be working
correctly.

Thank you all for your help and guidance.