Mystery Water Heater Gate Valve

[Troy's Bucket 74]

Just moved into a house with two water heaters and no one seems to know what this blue valve controls. Any ideas?

 

[TomFOhio]

That's a return line so the hot water gets to your fixtures quicker. If the left water heater goes bad then you can
shut that valve off and drain it without interfering with the other tank. Can't see if the other tank has the return
tied into it or not.

 

[Jeff Handy]

Is that pipe going down to the floor just a support leg?

 

[Troy's Bucket 74]

That's a return line so the hot water gets to your fixtures quicker. If the left water heater goes bad then you can
shut that valve off and drain it without interfering with the other tank. Can't see if the other tank has the return
tied into it or not.

Thanks Tom, here is another angle where it goes back towards the wall then diagonally up and into the wall but doesn't connect the to the tank on the right.





My main question concerning the gauge is we found it not fully opened or closed. Is there any reason it would be halfway open or should I make sure it is turned all the way open?

 

[Troy's Bucket 74]

Is that pipe going down to the floor just a support leg?

Correct, it has a cap on the bottom that just rests on the floor.

 

[Jeff Handy]

Looks like you have a valve on both sides of the recirculation pump, very handy to isolate it to swap in a new one easily.

I think a gate valve is not meant to be a throttle, and best left fully open.
Or wear and tear from friction can damage the gate.
But pros can weigh in to verify or dispute.

And that might not be a gate valve anyway.

 

[Diehard]

It sounds like it would be a good idea for you to get totally familiar with all that piping around the water heaters.

Are both water heaters in use and connected together?

Take pictures for ALL water piping associated with the heaters.