Looking to move a circulator and fill valve, system is now pumping toward tank

CodyM4399 · January 5

I very much appreciate your time so let me make this short and sweet. I’ve noticed my circulator pump on my boiler is pumping toward the expansion tank…no good from the standpoint of physics and all these great books from Mr.Holohan. I’m looking to also move my fill valve from its current location to the point of no pressure change, as a T between the air scoop and expansion tank. I’m only on my first year in the trade and don’t work with hydronic systems too often, so I’m really wondering if my idea will work and so I can carry it out, I don’t see why it wouldn’t work but we know how that line of thinking goes…right? Thank you for your time guys.

LRCCBJ · January 5

You are correct in the preference to pump away from the tank rather than toward it. But, before you take out the wrenches and the soldering tools………….consider the fact, in not too distant past, that all the boiler manufacturers would provide packaged units with the circulator on the return. 98% of the time, the systems worked fine. And, if they failed to work fine, raising the pressure on the boiler usually cured the problem.

So, is your current installation ideal? No. Will it affect the operation of the boiler? Likely not.

The location of the fill is typically irrelevant. You use it once and forget it.

hot_rod · January 5

I don't think you system will see much gain from the repipe. In some systems pumping toward the tank can pull a negative pressure in the piping. Air could get into the system from an auto vent located at that negative pressure area.

Another option would be to add a tee where the red purge valve is and move the tank connection to that point. Now you are piping away with a simple piping change.

A B&G drawing that started the Pumping Away movement

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pedmec · January 5

i'm with @LRCCBJ on that. if its working fine and your not having air problems don't worry about it. This is the the difference between commercial and residential. Smaller circulator pressure differentials wont really come into play where as in a commercial setting it can really be a problem.

But…. if you need an option you can do the Weil-Mclain way. Put the expansion tank and fill on the return side right before it enters the boiler or on a tapping in the boiler. Both put the expansion tank on the suction side of the circulator creating a pumping away system.

CodyM4399 · January 5

https://forum.heatinghelp.com/discussion/comment/1832114#Comment_1832114

That’s certainly a much more sensible approach than what I had in mind. So something like this would be appropriate? Appreciate the help

hot_rod · January 5

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Here is a little demo board I'm building for some videos. With a 8 psi fill, this circ flowing @10 gpm. The circ adds about 6 psi when pumping away from the expansion tank. Or subtracts when I switch the expansion tank connection to the discharge side of the circ.

It really depends on the circ and the piping circuit it is attached to regarding the pressure differentials.

Gauges and PT ports allow me to check pressure in various locations.

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Looking to move a circulator and fill valve, system is now pumping toward tank

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