What’s this and why?

[Mitchell-DIY-Guy]

So my neighbor asked me to come and tighten up their lavatory faucet. Which I did.
Underneath the sink in the vanity, however the faucet is not connected directly to the shut off, so it goes through this contraption in the photo.
Functionally it just seems to be a connector. It doesn’t seem to be doing anything like mixing but then again, I don’t know. It does add another set of shut off valves, but everything seems to be connected with the same 3/8 inch standard fittings.
Anyone see anything like this?

 

[breplum]

That is what is referred to as a 'bridge'. It mixes hot into cold for 'one pipe' hot water recirculation...the worst effect being that the cold water is always hot until flushed out with the hot faucet opened.
Used typically with Grundfos kit. https://www.amazon.com/Grundfos-595...ocphy=9032015&hvtargid=pla-350545422178&psc=1

https://www.amazon.com/Grundfos-595...ocphy=9032015&hvtargid=pla-350545422178&psc=1

 

[Mitchell-DIY-Guy]

Hmm. Will have to tell the neighbors that they have hot water circulation. They don’t know. Their heater is a tankless in the attic.

 

[havasu]

If you look closely, it does not look like a Grundfos bridge. It looks like a mixer, without a thermostat.

 

[breplum]

If they don't have a pump anywhere, then it should be removed.
Watts makes them too

 

[wpns]

Does it connect to both hot and cold? Looks like someone kludged up a 3-way manifold. What else is connected?

 

[Mitchell-DIY-Guy]

Does it connect to both hot and cold? Looks like someone kludged up a 3-way manifold. What else is connected?

The hot from the wall shutoff connects to the left side, braided flexible hose. The cold to the right side, again with a braided flexible hose. At the front of this bridge are two short pieces of white PEX and then right angle shut offs. The faucet lines connect to these shut offs. Nothing else connected.

Neighbor had no idea about it, or a pump or circulator. The only thing they know is the tankless hot water heater is in the attic…

 

[wpns]

Ah, then it's probably what breplum said, an 'automatic' hot water recirculation kludge, but nonfunctional because of the tankless.. I'd pull it out, but I'm not sure I'd want to own it, which is usually what happens when I help a neighbor. 8*)

 

[Mitchell-DIY-Guy]

Just going to leave it there until the next problem…