Good Afternoon Everyone! I hope we can get some advice, it's kind of a long story. I'll try to start from the beginning but may be off by a month or two.
Last May 2011, the water heater that came with the house shut off and would not light. This old model was before the "sealed combustion chambers". We had a plumber come in and he described it as when he was able to create an ignition there was a big flame and believe he mentioned deterioration. Well, solution was a brand new water heater. It was purchased and installed by Home Depot and everything was fine again...till about three weeks later.
Late May 2011 - Found ourselves with no water and when we checked the water heater the pilot light was completely out. We couldn't even get it to light again, but could vaguely see the "lighter" charge up. Also, the window of the chamber was completely fogged up. So we contacted Home Depot and eventually a replacement water heater was provided and installed, with modifications to the vent.
Here's where it really sucks...we went through this round three times. Three brand new water heaters. The new one would last, then die a few weeks later. We've had the gas supply tested, was good. Contacted the manufacturer which had little thought, but did recommended a "separate plumber" from Home Depot contracted.
August 2011 - A symptom we did notice pretty consistently prior to a water heater dieing was "the window would fog up". Once the water heater died, it would be completely fogged up. When we noticed slight fogging, we contacted a new plumber to assist us. He opened the chamber and found tons of white powder on the burning plate and up inside the water heater where it vents. He wasn't sure what it was. But he cleaned it out and wiped the window cleaned. He re-did the vent stack towards the top - *didn't like how the previous person had done it* and checked for suction or draft from the vent opening. Also, the burner is sometimes a sporadic violent rotation between blue and orange/yellow.
April 2012 - Almost a year since the original water heater died.
So anyway, it started to fog ever so slightly, but it never died these past several months. However, today I noticed the window was much foggier and I'm starting to worry. Anyway, I've been searching about this "white powder" and "venting" and noticed the following forum post:
Rheem white powder near exhaust vent?
Then it dawned on me, shortly before the original water heater died...our roof along with three neighboring units was replaced. Could something they have done be the whole cause of the water heaters failing? And what can we do to get this fixed permanently. We were going to contact the plumber again, but is this powder the key to our issue and if it is...how we explain to them what this is or even how to identify it? Any help is greatly appreciated, thank you for everyone's time!
White Powder -
Fogged Window -
Scorch-marks on right-side
Fogged Window -