Hello, I have a water heater that's hooked up in a way I can't explain. It has the usual hot and cold lines coming through the top, and a gas line going in the side, and a drain valve coming out the side (near the bottom). But there's a "T" off the drain valve, with a pipe running straight up into pipes that eventually lead straight back to the rest of the hot water pipes (in the basement) - in two places. (Both about 15 pipe-feet away from the heater - in opposite directions.)

Is there any possible purpose for this? It seems like it would just mix cold water from the bottom of the tank back into the hot water system. (Or maybe mix hot water from the rest of the system back into the water heater?)

Here's a picture of the heater:



To reiterate - that extra pipe connects back to the same set of pipes as the regular 'hot' outflow pipe - in two different places. (And nowhere else.)

Thanks for your help!

quote...
"(Or maybe mix hot water from the rest of the system back into the water heater?)"
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exactly. it is a gravity recirculating line. there must be a check valve in there some where to avoid cold water going from the bottom of the tank into the hot pipe.
also all the hot should be insulated from the points where it connects to all the way back to the tank. leave off 18" of insulation right at the tank drain connection to create the recirculation.

Huh. Thanks! (There is no insulation, but that's fixable.)

I looked for the check valve, and it seems to be there - but pointed the wrong way! You can actually see it in that earlier picture, right at the top.

I also took a closeup:



The arrow is pointing up - away from the tank. Is that how it's supposed to be?

That is a ball valve. The directional arrow is to orient the valve during installation for the drain side of the valve.

Yes, thanks - I eventually did a bunch of reading and realized my mistake. Today I went and looked for any other sort of valve - and there isn't one. I'm going to try to figure out a way to test it.