The Johnston 358 series boiler is specifically manufactured for the state of Ohio with 358 square feet of heating surface.
In the State of Ohio, boilers over 358 square feet of heating surface requires a licensed operator, and boilers with under 358 square feet of heating surface does not require a licensed operator.
The Johnston 358 series meets all of these requirements with units or processing applications in sizes from 80 to 250 horse power. Steam, 15 to 250# pressure- higher pressure designs are available. Hot water, 30 to 160# pressure with a 250 degree maximum water temperature – up to 250# water pressure and/ or 400 degree water temperature available on special order.
Ratings are based on 358 square feet of heating surface, measured on the fire side (ASME METHOD). Custom designed forced draft burner matched with large furnace volume and primary heating surface, provide for the proper combustion and guarantees and average 80% efficiency throughout a 30-100% modulating range.