FR-Series High Energy Efficiency Boilers FR-98 | FR-122 | FR-147 | FR-173 | FR-205 | FR-232 | FR Series Boilers are the choice of heating professionals for reliable, energy-efficient heating. A popular replacement for old, fuel wasting systems, FR boilers are also ideal for new homes. All FR Series Boilers are backed by a Homeowner's Lifetime Limited Warranty The FR acheives top ratings for combustion efficiency, overall efficiency and net stack temperatures. In comparison with most cast iron boilers, the FR heats up quickly, and has less pick-up and standby loss. What's more, the FR matches any boiler on the market for long lasting quality. Larger water content is an advantage for the new Radiant Systems and Cast Iron Radiation. The high-efficiency combustion systes features a flame retention burner and natural draft firing. This provides practically smoke-free operation with no flame pulsation.