Expansion Tank and Tapping into Existing System

[ME27272727]

I'm tapping into a steam fired variable primary hot water heating loop with a CHP loop, in what will then almost resemble a primary secondary piping arrangement. Would the pump for the CHP loop need its own expansion tank and air separator? My current line of thinking is that if the added system volume is significant enough to warrant more expansion tank capacity, then I should look into increasing the size of the existing tank on the suction side of the distribution loop pumps rather than adding a section expansion tank to the CHP pumps. Thanks.

 

[Compositepro]

There should only be one expansion tank per closed system.

 

[LittleInch]

"Almost resemble"?

Can you sketch a schematic?

From the description it sounds like it is one system so would only needed one tank, but a drawing would help a lot.

Are there any actuated sectioning valves that isolate the system?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[ChasBean1]

If the systems are hydraulically connected without checks preventing expansion or contraction one way or the other, you should be good. If you are making the system much bigger (higher volume), the existing expansion tanks might need to be replaced by larger models.