Posted by John Harvey (148.65.227.75) on April 27, 2008 at 00:04:18:
In Reply to: gas water heater + expansion posted by Chris Shaw on April 26, 2008 at 19:46:13:
I don't have an explanation of what the problem is, but I have noted that over the past several years, water heaters are installed with a small pneumatic expansion tank like found on hot water heating boilers now. Possibly your water heater really isn't large enough for the immediate draw, so instead of replacing your hot water with cold at a rate that simply mixes it with the existing hot water in the tank, it sort of layers itself, and makes a wad of cold water in the tank. That is just a guess on my part.