circ on water heater?

John S_2

30 gal electric low-boy in crawlspace below dentists office. Someone installed "Lil Red Booster" pumping toward the tank I guess to provide 'instant' hot water. However they neglected to by-pass any of the sinks so there is no continuous loop. All the pump is doing (as far as I know) is adding it's pressure diff to street pressure (averaging I'd say 75#) and the thermal exp pressure.
When I got there @ 8am Monday pressure (measured at the drain) was 110# and the relief valve was dripping. I was there to do annual maintenance on 2 warm air oil-fired units not to see about the leak. I left the gauge on while I did my thing and kept checking it. Pressure was averaging 75# and twice went above 110#.
So I told the office mngr they would need a reducing valve and thermal exp tank and my office would give them a quote on it. Here's my ques: If the pump isn't doing what it was intended for, can we just remove it? And will that be enough to keep the pressure low enough not to cause problems? I say they still will need the PRV and tank but I have a feeling they (and possibly my management) will want to do the cheapest thing they can get away with.
Thanks for any input you guys can give!



Sheeesh!

Larry Weingarten

Was there hot water...

...quickly at the taps? If so, there is probably a "bypass" installed under a sink somewhere to allow flow from hot to cold...an thence back to the heater. Have a look around before removing the pump!

Yours, Larry

Michal

check all sinks

what that pump is or should be doing is be a recirc pump to keep water hot at the faucets, it should be piped from the hwh to the faucets on the hot side of the faucet and be circulating water back. they do not need a pressure reducing valve if there averageing 75 psi, a expansion tank as well should not be required. can you send a pic?

John S_2

No they aren't getting instant hot water at the sinks. They weren't even aware of the pump. I looked for the bypass under the sinks and all through the crawl. The pipes aren't even hot unless some one opens a faucet. It's not circulating. That's why I thought of getting rid of it. How can you say they don't need a reducing valve or exp tank when the idle pressure is going over 110# and the relief valve is weeping? I was told anything over 75# is too high.

Mark Eatherton1

What...

is the cold incoming pressure of the water. The lil red booster is only capable of generating a few pounds of pressure. I suspect that you're looking at the residual pressure caused by water being heated and expanding, not water pressure being generated by the little booster...

If you go to the far end of the system, and create a cross connect between the hot and cold water, with a check valve in the cross, you will have an instantaneous system. However, they will have to run the cold water for a long time before it gets cold because the cold water line is now being used as the DHW recirc line. Better off IMHO, to install a seperate circ line from the furthest P.O.U. and bring THAT back to the source.

THe "spike" you're seeing could be caused by kinetic energy of someone closing a flowing valve quickly. If it happens in the blink of the eye, it's kinetic. If it happens over a period of time, its thermal expansion. Make sure you adjust the air charge of the tank to match minimum static pressure before you install it (75 PSI).

ME

John S_2

Right, that's more like what I was thinking. I'm pretty sure it's thermal expansion that's causing this problem because it seemed worst first thing in the morning when the system had been idle over Easter weekend. I wasn't hearing that distintive banging of the pipes like with kinetic pressure changes and never saw the gauge reading change quickly. I didn't mean to imply that I thought the pressure diff of the pump could cause this problem. On the contrary, I felt removing the pump would not solve anything.

Rich_18

Meter

Has the water meter been replaced? The new water meters have check valves ,if so ;domestic extrol tank