The Hydra Smart RTC is a condensing gas tankless water heater. It is manufactured with a high grade stainless steel heat exchanger to provide endless hot water. The unit has a 10 to 1 turndown and is highly efficient, with a .95 Energy Factor, making it Energy Star certified. The Hydra Smart RTC is eco-friendly with a low NOx combustion system with a highly innovative gas leak detector. The RTC will supply high temperature water for sanitation and will cascade up to 18 units. You will never run out of hot water with this advanced modulating tankless water heater, available in natural gas and liquid propane.