Backdraft problem

[Greg-s1]

Ever since I replaced my water heater, the pilot light on the new one occasionally goes out. I assume it's backdrafting as it seems to only happen on overcast or windy days. The WH is right next to the chimney and the vent duct seems to be good with regard to length and slope. I haven't been up top to look but it seems my home inspector years ago mentioned there was no cap up there. I never had an issue with the old water heater so I never worried about it. Would a cap possibly fix this issue? If it doesn't, can I put a inline fan on the vent duct? Any options I have overlooked?

 

[TomFOhio]

Take a match and light it then blow it out and put the smoke from the match up to the divertor on the top of the tank and see if the smoke sucks up in the vent pipe. Also I would put a cap on like it is suppose to be. If none of this helps then consider a chimney liner down through. Does your furnace go into the chimney too. Let us know.