Heater not working - 46deg inside!

[zometool]

[zometool]

Oops, with all that new info I momentarily mixed up jolt's info w/ [e-mail]'s info. I deleted the entry I just posted b/c it was a little confused about matters of credit. In case anybody read it, I'll correct myself - Thank you both, but Jolt, you're the person I meant to lavish praise upon. Everything YOU said was right-on! Now I'm gonna fix my furnace and unfreeze myself! A successful thread, for sure! I'm very grateful!

jolt wrote:

[Doug]

Where'd you come up with the above info?

Until the last 15 years or so, most furnaces including horizontal ones typically used in crawl spaces had pilot lights. There nothing wrong or unsafe about that, unless you like to pour gasoline down into your crawlspace, in which you're likely to have greater problems than a pilot light...

I've got several places with horizontal furnaces installed in the early 1980's that are horizontal flow and in crawl spaces.

As another poster pointed out, the only reason for elimination of a pilot light was to achieve SLIGHTLY increased energy efficiency.

I installed a furnace in 1994 that still used a pilot light. It had an AFUE of 78% versus the identical furnace with spark ignition which was rated at 80%. I didn't sweat the 2% difference. I got the pilot ignition furnace at a $200 discount...cheapsake that I am...

As for the original poster, I suspect that since his furnace is more recent, it doesn't have a pilot light.

Also, the fact that his fan comes on is a clue. Many pilotless furnaces have a blower control PCB that uses a simple time delay to turn on the fan rather than a heat sensor. Thus, for example, if the thermostat calls for heat, the main blower turns on 2 minutes later, whether or not the main burner has achieved ignition.

Most later furnaces also have a draft inducer or small blower that starts the air flow up the chmney. If that blower doesn't come on the main burner will not ignite since there is a draft flow sensor switch that must turn on to allow ignition.

To trouble shoot the above type of furnace, I'd turn the thermostat all the way up, check to see if the draft inducer blower was operating, check for a glow at the hot surface igniter or a snapping spark at the spark ignitor, if it has one and also check to see if there is a main control PCB with indicator lights. Many recent furnaces have indicator lights that light in a sequence showing certain fault conditions. If he knows how to use a volt/ohmmeter, more tests can then be done...

Doug

[Stormin Mormon]

• Bad wire to the thermostat

• Hot surface ignitor not working properly

• Flame sensor gone bad

• Bad gas valve

• Burners clogged

• Safety limit switch tripped

• Bad transformer

• Fuse opened (possibly one on the circuit board)

• Bad circuit board

How about some more information. Are you familiar with the use of a VOM?