Circulator on supply or return and Danfoss valve change?

[goosegunner]

I am installing a different boiler and I am trying to decide if I should make any piping changes. I have had my circulator on the the Supply, down stream from my air eliminator and expansion tank connection.

Wondering if I should move it to just the left of the Danfoss on the return to the boiler?

If so Where would you put the air separator and expansion tank connection?

Also thinking about changing the Danfoss to a valve that fully closes and doesn't need to be throttled like a Thermovar LK 823 or Caleffi Thermoprotec 820.

Worth the effort and expense to change 3 way valve or no?

I will also be putting in a purge valve just to the right of the Danfoss and purge flanges on the top circulator. To help when filling the system. I have had some tumbling pebble noise at the top of the bypass T and need some way to purge better for new setup.

 

[maple1]

I don't have any experience with a Danfoss, or a layout like yours.

But my loading unit is plumbed down low, on return, just outside the boiler return fitting - and I think the design of a loading unit is similar to what you are thinking of doing - circ pulls through the valve. And I think that is the typical install location of a loading unit. For what that is worth? Also my expansion tank is plumbed into my zone return line, just upstream from my zone circ, which is just upstream from my loading unit. So it's down low too - on inlet side of each circ.

I can't say one way or the other if you would see any advantage changing it, or if it would be 'worth it'. But I have always thought having to use a ball valve to throttle bypass flow was a jimmied up way to overcome some sort of design issue. Throttling is not needed with my loading unit - so no direct experience there either.

(All that goes against the 'pumping away' axiom - but seems that axiom isn't really super important with these setups).