Passive pump/valve for recirculating heat loop

[Gary Fritz]

My brother's house has a circulating hot-water loop running from the heater to the kitchen on the other side of the house. I've seen those before, but his loop is **passive**. There's a doohickey that somehow circulates the water, but no pump. No power. Totally passive. I have no idea how this thing works inside -- is it a Tesla valve or something similar??

Lately it's sprung a leak. He's tried a bunch of things -- JB Weld, other epoxy, fiberglass tape, etc. Nothing successfully plugs the leak. He's asked his local plumbers and they have no clues. He's looked everywhere he can think of online, no joy. He can't find anything like it.

Any suggestions where he might find a similar item, or some way to replace or repair it?

Many thanks!

 

[breplum]

so old you'll never find one. I remember them in the trade magazines for years. Might have even installed one thirty something years ago.

 

[Gary Fritz]

So this useful functionality just got dropped, with no replacement? What do you do with an existing installation? “So sorry, your hot water feed doesn’t work any more, and there’s no way to fix it” ??

 

[wpns]

What are the three pipes connected to? If there were just two I could see it being a zero backpressure check valve, but I don't understand three.

Theoretically convection will work if the return line goes to the bottom of the hot water tank...

 

[Gary Fritz]

Brother sez: "It’s a little hard to tell exactly which is which as the pipes are buried in the ceiling but I *believe* the top one is the main hot water feed to the kitchen, the small top one is the recirculation line and the bottom one comes directly from the water heater."

Not terribly helpful, I suspect. I can ask him to take a wider photo, but here's one with a bit more surrounding context. The hot-water feed comes from the tank in the background, which is actually just storage. He's got a boiler for in-floor heat, and the water heater taps off that. I think the gizmo in the center adjusts the flow from the boiler to control temps?