On 11/14/2010 8:39 PM, hr(bob) wrote:
On Nov 14, 7:47 pm, The Daring
wrote:
On 11/14/2010 4:04 PM, wrote:

Hi;

I have a ruud furnace that wont stay running. The unit goes through
the start up cycle. The electronic igniter will start sparking, and
the flame will ignite. It will run good for about 5-7 seconds, then
it it will go out like the unit cut the gas off. I think it is a
flame sensor, but I am not sure what it is called.

This furnase has a circuit board with 3 leds. two are green and one is
yellow. It says Flame. This light flashes, but the other two stay
solid green. I cant find a manual to see how to read these. Any help
or pointers would be appreciated.

Does your furnace have a draft inducer fan? There can be one or two
safeties with a draft inducer. A centrifugal switch on the fan motor
and a diaphragm operated pressure switch to detect the air pressure
cause by the running fan. The diaphragm switch will be round plastic or
metal with a silicone rubber tube connected to the draft inducer
housing. The air line could be bad or the connection to the inducer
housing could be clogged. A piece of wire can be used to clear the
connection and you can blow gently on the tube and listen for a click
from the diaphragm switch. You can jump out the safeties to test them
but never leave the furnace running like that. There are several sites
where you can post a question about your problem. You'll need to post
the model number and such because the folks reading your question can
be dealers for your specific equipment.

http://www.hvacmechanic.com/index.php

http://toad.net/~jsmeenen/index.html

TDD

Couold there also be a thermocouple to sense thast the flame is
actually on?

No, it has an electronic igniter. Most new NG furnaces use a hot surface
igniter which is a silicon carbide or nitride resister which glows red
hot and will ignite the pilot when gas hits the igniter.

http://homerepair.about.com/od/heatingcoolingrepair
/ss/furn_electr_ign_4.htm

http://preview.tinyurl.com/2g27es8

The igniter is used in conjunction with a flame sensor which is a heat
resistant metal electrode that sticks into the pilot flame. Both devices
are hooked to the control module which will turn off the igniter when
a flame is detected by the flame sensor circuitry.

TDD