Pumping Away-------sort of

Ron Schroeder_2

Hi,

I am working on a Buderus oil fired boiler that has the circulator in the return. The expansion tank is on the suction side of the circulator so it is "Pumping Away" from the tank.

Does anybody see a problem with this arrangement or should I re-plumb the near side piping.

Thanks,

Ron

DanHolohan

It will work

as long as there's just that one pump.

Al Letellier

pumping away???

> Hi,

>

> I am working on a Buderus oil fired boiler

> that has the circulator in the return. The

> expansion tank is on the suction side of the

> circulator so it is "Pumping Away" from the

> tank.

>

> Does anybody see a problem with this

> arrangement or should I re-plumb the near side

> piping.

>

> Thanks,

>

> Ron





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Al Letellier

pumping away---sort of???

Maybe in theory,Ron, but pumping away mean placing the air elimination device at the point of lowest system velocity, so with the pump on the return, it is just AHEAD of the air device, which is now at the point of highest system velocity, making it more difficult to eliminate the air.
There are thousands of systems out there piped like yours. Properly purged, it should work just fine. I wouldn't repipe it unless it really gets into "air trouble". I am a firm believer in pumping away, but the old way works too.

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Ron Schroeder_2

The circ. is after the air elimination device (standard air scoop at the expansion tank)---------but there is a second pump. Both pumps are on a Tee at the return. The second pump is for the indirect DHW tank. There is a flo-check in that loop but not in the heating loop. The heating loop is monoflow Tee's and will not self purge. Once the air is bled from each baseboard it runs fine but only one of the baseboards will heat until the other baseboards are bled.

Sometimes I hate following in someone elses footsteps.

Plumbob

system velocity...?

> Maybe in theory,Ron, but pumping away mean

> placing the air elimination device at the point

> of lowest system velocity, so with the pump on

> the return, it is just AHEAD of the air device,

> which is now at the point of highest system

> velocity, making it more difficult to eliminate

> the air.


The water velocity before the pump must be the same as the water velocity after the pump...as long as there is no change of pipe diameter and no tees introducing additional water.

This follows from the famous Law of Conservation of Water.

Ron Schroeder_2

Hi Chuckles,

That's what I was thinking too.

DanHolohan

One circulator

is pumping away from the point of no pressure change, and the other is pumping toward it. This leads to system problems when both circulators try to run at the same time. I cover this in my Pumping Away book.

Ron Schroeder_2

With priority, both circs. won't be on at the same time but I see about the heat circ. pumping away and the DHW circ pumping toward.

This system will be really difficult to re-pipe. There are 6 zones piped in about the place the circs. and expansion tank should be. ----And it is in a tight location with very little clearance.

Ron