There are 1 valve, 2 valve, and 3 valve setups. How many valves are there in the water lines behind your water heater. Until we know that, we can't really answer your question.
When you say that when the valves are turned fully either way, you get no water, it sounds like you are opening one valve and closing the other at the same time. Both valves would need to be open to get water. I am going to make an assumption that you have a 2 valve system. You need to try 4 different valve settings:
1. top valve left, bottom valve left
2. top valve left, bottom valve right
3. top valve right, bottom valve left
4. top valve right, bottom valve right
One of those will have both valves closed and you get no water, the winterized setting. Two of those will have one valve open and one valve closed and you get no water, never used. The fourth will have both valves open and you will get water, the summer setting.
If you don't have a 2 valve system, this is not applicable.
Bobbo and Lin
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