Having two tanks will not reduce efficiency. Adding a buffer tank will help to keep the boiler from short cycling during demands from very small zones. Buffer tanks are not typically used in high mass boilers like your cast iron model but it will really depend on the size of the smallest zone.
I would recommend working with your contractor to determine if there may be another problem causing the short cycling and if a buffer tank is necessary.
Hi Joe,
That is a very clean installation!
Having two tanks will not reduce efficiency. Adding a buffer tank will help to keep the boiler from short cycling during demands from very small zones. Buffer tanks are not typically used in high mass boilers like your cast iron model but it will really depend on the size of the smallest zone.
We have a technical journal on this very topic that may help you. https://www.caleffi.com/sites/default/files/coll_attach_file/idronics_1…
I would recommend working with your contractor to determine if there may be another problem causing the short cycling and if a buffer tank is necessary.
Best Regards,
Cody Mack
Caleffi North America