Kitchen sink pressure pump???

[Richard Moore]

I found this under a kitchen sink today.

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It's a small pump, on a timer, fed from the cold stop-valve, going to the kitchen sink faucet. House pressure was fine at 55 PSI. The sink was fitted with a faucet-mounted Pur water filter. I know squat about these filters and my first thought was that the Pur filter needed extra pressure to function, or for increased flow when being used. I've checked the Pur website and can't find anything in the install & use manuals that would suggest the need for one.

But...I can't think of any other reason for it(?). I do know it's definitely not a hot water circulation pump. Not a big deal, I really don't "inspect" these filters, everything seemed to work OK, no leaks, etc, and I'm recommending the client ask the absent seller about it. I did tell him I would ask my "knowlegable on-line colleagues" about it, but I made no promises he would get an answer that way.

So...I'm curious! Never seen one before. Was wondering if anyone else had.

[Jim Katen]

Originally posted by Richard Moore

. . . I do know it's definitely not a hot water circulation pump.

It looks exactly like a hot water circ pump. Are you sure that it wasn't plumbed to pull the water from the hot angle stop and feed it into the cold angle stop?

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If that wasn't it, perhaps the PUR filter caused enough friction to cause the impatient homeowner to improvise.

- Jim Katen, Oregon

[Richard Moore]

Well...I'll be....!!! Jim, I thought I had the various risers traced, but it was such a rat's nest that it was difficult to keep track of what went where. Looking at your photo, it does make some sense that it might be a re-circ system, of sorts.

But, then my next question would be...if you are pumping hot water around the house using the cold water supply as the return to the water heater, wouldn't that mean that you would initially get hot water at the cold tap? That doesn't seem very desirable.

[Jim Katen]

Originally posted by Richard Moore

Well...I'll be....!!! Jim, I thought I had the various risers traced, but it was such a rat's nest that it was difficult to keep track of what went where. Looking at your photo, it does make some sense that it might be a re-circ system, of sorts.

But, then my next question would be...if you are pumping hot water around the house using the cold water supply as the return to the water heater, wouldn't that mean that you would initially get hot water at the cold tap? That doesn't seem very desirable.

Oh yeah. Sure. That's exactly what happens. It's a poor man's recirc system.

The slick way to do it is to have the pump controlled by a motion sensor on a one- or two-minute timer. When you walk into the bathroom, the pump starts. By the time you need to use it, the hot water has arrived.

I don't know how you'd do that with the kitchen sink, though.

- Jim Katen, Oregon

[Richard Moore]

It's actually kind of funny with the water filter in place. "Anyone want a nice refreshing glass of filtered warm water?"

Anyway...thanks Jim. I live and learn!

[davidlord]

Like Katen said its a poor mans recirculation system. Typically you will see these at the master bathroom sink which is usually the furthest point from the water heater.

I installed a dedicated hot water loop in my house when it was built so you get hot water instantly anywhere in the house.

[Tom Raymond]

Originally posted by davidlord

I installed a dedicated hot water loop in my house when it was built so you get hot water instantly anywhere in the house.

And you use that radiant heat loop often in Florida[^]

Tom

[ozofprev]

Man, ya learn something everyday!

WRT the filter, adsorption by activated charcoal is affected by pH, temperature and flow rate. The filter will not work as well when the water is hot, or is forced to flow more quickly (not the case here, but still a fact).

[davidlord]

Yea. Radiant heat.

[Richard Moore]

Originally posted by ozofprev

Man, ya learn something everyday!

Yep! I had already inspected the water heater and knew it only had the normal connections, which is why I was dead certain, but dead wrong, it wasn't a circ system. Never occured to me that you could, or would want to, use the cold supply as the return loop.

It wasn't even that big a house, the water heater was centrally located, and so it wouldn't be that long a run to the kitchen. Besides the filter, I have this picture in mind of limp lettuce after rinsing it with hot water.

Thanks to Jim and his prompt reply I was able to explain it in the report, along with the downside. And, of course, I know something I didn't before. TIJ is the best for this. If I had tried this over at IN I'm sure one certain individual would have cut and paste about 20 pages of code "explaining" (term used very loosely) everything BUT what I needed to know.