Water heater won't fill.

[Beachside]

I was sanitizing my fresh water system and drained my hot water heater. When I was ready to run the bleach solution from the fresh tank, the hot water heater wouldn't fill. Had the pressure relief valve open. After trying using the water pump I even hooked up to city water and never got water out of the relief valve. Pulled the plug and tank was empty. Kept running water though the system with both pump and directly to city water and water never came out of the heater's drain. Any thoughts?
It's on a 2014 Montana High Country 338DB with a 10 gallon Atwood heater.

[limit4]

I am sure you checked but it sounds like the by pass is on.

[bsmith0404]

Sounds like your water heater bypass valve is closed. Not familiar with your setup, but on the High Country there is probably a valve for winterize somewhere, try changing the position of it and see what happens.

[14george]

X 2 what they said

[limit4]

Hey Beachside, What was the outcome?

[Beachside]

You guys were right. Water heater bypass was on. Never use it so did not think to check it, but I must of flipped it at some point. As they say, always check the obvious stuff first. Thanks for the replies.