You mean kind of like a tankless water heater from Lowe's?
Otto
Actually, YES! There are two cylinders, a cold water and hot water.
Water comes in to the cold cylinder, is pumped into a heater chamber, gets heated, pumped out into the hot water cylinder, and then into the boiler. The "heater" is a very small tank compared to the big thing you see on top of the front of the boiler in an Elesco heater.
And BTW... This is for the Worthington Type BL.
The Worthington Type S is a much smaller device with just the cold and hot pumps in it, usually mounted up closer to the front of the engine, and the heater tank IS up on top at the front of the boiler, mostly buried in the smokebox section, but with a small rectangular section showing in front of the stack.
Finally, the SA is much like the S, but the heater appears to be completely down inside the smokebox at the front of the boiler.