Help I caused a leak! Understanding my multiple water heater plumbing..

So based on the advice in this thread http://ift.tt/1QGHw1H

I closed the valves and started taking off the supposed vacuum breaker from one the closer tank. When water started coming out. I thought maybe that was normal and that the pressure would quickly go down it didn't.

I also noticed that the cold water in pipe I was going to use for the ice maker was really hot even with the water heater off for a few hours. I then tried to relieve pressure by opening a faucet. Water came out piping hot and the other hot water tank burner kicked on which caused the cold water in pipe on the one I was working on to go cold.

Of course the partially backed out vacuum breaker no longer has sealant on the threads and is slowly leaking :wall:

I realized that I really don't have any idea of what's connected to what and what goes where.

I'm hoping that if I post some pictures maybe someone will recognize the setup or at the very least give me some ideas on tests I can do to try and figure out what's what.

Pictures:

Here are the hot water tanks. The closer one is the one I tried to work on.



Pipes coming out top with valves


Pipes coming out bottom with valves


Close up of top left pipe (same both heaters),

Close up of top right pipe (same both heaters)


Close up of pipes from bottom of heater where it goes into the wall Same both

Extra valve in between heaters near floor


What makes it even more complicated is I don't know whether the cold water where ever it may go in comes from the street, or passes through the two water tanks we have or is connected to both systems.

This is the lower tank with the water which comes from the street coming in from below on the right. The water heaters are just to the left of this picture, could possibly be connected??



Water from that tank is pumped to this tank on the roof from which it goes to most the fixtures through out the house (but not the ones in the back yard, running those will not draw water through the tanks)






1. Does anybody know whats going on with my plumbing?

2. Any ideas for how to test whats going on?

3. Any way to temporarily seal the threads on the vacuum breaker that I started backing out while I can't depressurize the tank?


Thanks in advance.

Help I caused a leak! Understanding my multiple water heater plumbing..