HTP PHR-199-55 | Boiler + 55 Gallon Storage Tank | 66,000 -199,000 BTUs | 95% AFUE

A: This is a boiler with a built-in buffer tank. The Pioneer features a single loop installation – the heat exchanger is immersed in water and protected against flashing due to low flow conditions. The Pioneer is retrofit – a direct replacement for low to mid efficiency cast iron boilers. Unlike other modulating condensing appliances, the Pioneer features a built in buffer tank, eliminating the need for primary/secondary piping design due to thermal mass.

Product Literature: https://htproducts.com/pioneerdocuments.html Answer provided by:  Kris (9/29/2022)