Water Heaters Greens Heating & Air Conditioning can install any size conventional water heater. But consider this green option...a 98% efficient tankless water heater! Endless hot water never looked so good. By heating water only when it's needed, gas tankless water heaters cut water heating expenses by at least 30% while also providing continuous hot water delivery. Also, when you consider the size - about the same as a carry-on suitcase - think of the space you'll create! Advantages of Tankless Water Heaters: Endless Hot Water Lower Energy Costs Performance & Longevity Navien Tankless Water Heaters A Navien Condensing water heater reduces up to 964 lbs of CO2 per year compared to a conventional water heater, and up to 324 lbs of CO2 per year compared to a tankless water heater. Because this product boasts the industry's highest efficiency, rating (98%) means customers can cash in on low annual operating costs as well as receive the best payback, compared with conventional tankless or tank-type water heaters. Navien's Condensing 98% Tankless also enjoys the highest gallons-per-minute (GPM) when comparing input BTUs.