true to what inspector 57 said back draft can blow out pilet: since this is NEW TC I would still suspect it or the ground problem. I build ovens for a living and work on the systems, as stated the thermocouple is a generator uses a dc voltage between the flame and the ground, if the ground is dirty then you cant get DC... as all you have is a slight charge and no where for it to go. it stays on for a while and when the main lights the charge goes up the ground resistance changes and as soon as the main flame drops out the signal is lost for the pilot...
the fact that it stied lit when it was cool and moist tells me the dampness helps/helped out I'm pretty set that is the rusty ground problem. and or the new replacement thermocouple is not connected very well, a simple remove and reinstall will problably help out. and if you remove it might as well clean all the mounting surfaces. the water lines should provide a good ground but that is not always the case... That little red button is on the valve. it is held in by you untill the thermocouple voltage can hold it in electromagnetically. it could be a bad valve but most of the time the valves are OK and changed due to lack of troubleshooting by the mechanics part... also if you go to a persons house and only change a 5 buck thermocouple then you give them a 100 buck bill they get grumpy... on the other hand you tell them that the valve went bad and change it they are less likely to get mad...
Intermitant problems are a P.I.T.A. to find, most recent one is the furnace which uses a bi metalic stitch to heat instad of the thermocouple but does same function. it works 99% of time and when you go back to check it is reset when pulling the cover from the furnace! so finding it againe and can't duplicate can get to be a madning experiance. I could have changed valve and switch but chose to install a 24vac light into the circuit so that I could troubleshoot from the phone. (woman was in dire circumstances can't aford to pay for un needed parts.) light buld price was 2 bucks and few min time I didn't charge for. showed her what to look for when it happened next time she did and it aws the bi-metalic switch... I got one from e0bay for 9 bucks but she can't pay right now I'll fix t for her when I get time and won't charge her only for hte parts as I know her circumstances and what is happening in her life.
anyhow with a hot water tank that old you are looking for problems and the tank will prbably go pretty soon too. we are lucky to get 8~10 yrs out of a tank in our neck of the woods with the heavy hard water and excess salt treatments the water systems recieve here... nothing usually goes wrong in that time and the tanks usually end up leaking someplace. even the glass ones! I got stuck with that one 25 yr warrenty and was outin about 8 yrs. anyhow jsut my thoughts of the problem...
Mark M /forums/images/graemlins/smile.gif
