Furance pilot goes out frenquently in cold days

I have a new gas steam heat furance that is less than a year old, with a consistently on pilot. The pilot goes out almost every day when the outdoor temperature is bellow 25F, but it is fine at other time. I have replaced 3 thermocouples and even ask the installer to replace the gas Valve for me, but none of these helps. I also make the fresh air outlet bigger and clean the chimney but without any improvemant.

I have a 75 gallon water heater with a consistently on pilot in the same boiler room. The gas for the water heater is from the same gas supply. And it goes to the same chimney. This water heater never has problem with its pilot.

This house is in NYC, where the houses are close to each other. Someone mentiones that it may be a drip of water from the furance that kills the pilot, but I don't see any steam or water at one time that the furance reaching the cut-off pressure of 5 psi couple cycles, and the water level inside the furance is also not too high when I see the pilot is off.

There is no window to outside world from teh boiler room other than the fresh air inlet and the chimney.

Another thing that I am not very sure is: it seems that the pilot usually goes out in the afternoon, becuase when I go there at noght after work , the water inside is still a bit hot. But because I did not live there, I am not very sure when it goes out exactly.

Any idea or suggestion?

Eric

Replace w/ pilotless?

Have you checked with the manufacturer? Is there a way to convert to a pilotless ignition? Since the house is unattended, this would also save on the gas consumed by the pilot. Most pilotless ignitions today are pretty reliable.

The corralation between low outside temp and the pilot going out must be more that a coincidence. Could this boiler be getting the brunt of a downdraft in the chimney - that blows out the pilot? Cold air = heavy air which could cause a downdraft. Or does this boiler have any sort of flue pressure saftey switch which senses a reduced draft or backdraft and shuts the system down?

These are all (somewhat) educated guesses - but they might help you ask the right questions of a manufacturer rep.

Let us know what you discover.