On 31 Jan 2006 19:54:48 -0800, "paaji" wrote:

Since yesterday Pilot light in furnace was out so i went out bought
thermocouple and replaced it. I wasn't able to light up pilot light
after so many tries I held i down for 15 minutes. Finally it woked and
remains lit. But when I turn on the thermostat(manual) not automatic it
remains on then goes off. Also other thing i noticed it if put the
thermostat to max pilot goes out right away. Could it be Thermostat or
something else? Thanks

You might have a partially clogged main gas valve.
I've seen this quite a few times. Most such valves have an input
screen to filter the impurities out of the gas. It clogs with time due
to sediment and the output gas pressure drops due to the restricted
flow.

To me, the hint is your statement "when I put the thermostat to max
the pilot goes out right away". Thus there seems to be a pressure drop
when the main gas valve opens.

In an emergency when it's been zero degrees at 2:00 AM, I've opened
and cleaned out gas control valves. However, it's not something that I
recommend and suggest you get a replacement or better yet, hire a
repairman.

Also, makes sure that the pilot oriface is not partially clogged.
The pilot flame should be mainly blue with the tip of the thermocouple
immersed about 1/3 of the way into the flame.

Doug