PVI's Power VT is a condensing firetube boiler with part-load efficiency up to 97 percent. Four sizes are available from 399 to 1,000 MBTUH with 3 to 1 turndown on the largest model. Boiler can sidewall-vent through up to 500 equivalent feet. Steel vessel is ASME-stamped. Stainless steel parts and polymer coatings are used in condensing areas of the boiler.