Pump position on sealed system

[abh]

Could anyone please explain whether one of these systems is better than the other?

Sealed system, heat only boiler, pump on flow, just after boiler, expansion vessel on inlet side of pump.

or

Same as above, but pump on return, just before boiler, and expansion vessel on inlet side of pump.

Am I right in thinking that in both cases, the expansion vessel is the neutral point, and therefore the rest of the system is under positive pressure, whether the pump is on the flow or return, and therefore both systems are equally good?

thanks

 

[lor]

hi,
in this months "HPM" Roy Oxley has written an article on just that.

he reccommends the pump is placed on the flow with pv on the inlet side so the system is under positive pressure
yes the pv is the neutral point

 

[abh]

Thanks for that, lor. However, if the expansion vessel is on the inlet side of the pump, won't the whole system be under positive pressure whether the pump is on the flow or return.

The only part under negative pressure will be the section between the expansion vessel and the pump.

Or am I being thick!