I have no idea what's going on with my piping.

Basically, yes. I have Fleck valves on my tanks, all with bypasses. To rebed a filter or work on the valve, I turn off the main water valve and relieve system water pressure, then put the valve in bypass. At this point there's no pressure in the tank, so I can separate the valve from the bypass module and do whatever I need to do with it. Normally, I don't want any water to be used at all with a tank out of the system (for example, with the GAC tank out, there's a nasty chlorine taste and smell, and it doesn't do the softener media any good), but I can get along without softened water if need be, so if I'm working on the softener, I can turn system water back on while I'm working on the valve. I have a spare tank, so if I'm just rebedding one, I can have the old tank out and the rebedded tank in in about 10 minutes.

So it is looking like the bypass valve is just broken. I shut it off, but there was full pressure at both the right and left sides. Arghhhh...

LOL, that is why I stopped using gate valves 20 years ago. It is also another reason that the valve mounted bypasses are preferred to 3 valve designs in smaller application. The valve mounted bypass is very cheap and easy to repair/replace if it is ever needed in the future.

amateurplumber1 said:

So it is looking like the bypass valve is just broken. I shut it off, but there was full pressure at both the right and left sides. Arghhhh...

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Any mixer-type faucets on while you tested?

Mikey said:

Any mixer-type faucets on while you tested?

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I've tested that once. Did not affect the faucets at all. Neither cold nor hot, or mixed.

Did you ever make that system diagram I recommended in #11?

amateurplumber1 said:

So it is looking like the bypass valve is just broken. I shut it off, but there was full pressure at both the right and left sides. Arghhhh...

Click to expand...

You didn't know that opening a valve without shutting off the water before that valve that you'd get full pressure flow!!

Gate valves are a very bad choice for a valve that is left in one position for a long time. Usually they break off the stem that is connected to the 'gate' as you try to open or close the valve; or the gate won't go all the way closed which causes a leak that usually can only be fixed by replacing the valve.