April 16, 2015, the minimum Energy Factor (EF) ratings for virtually all residential water heaters increased. An EF rating measures the annual efficiency of a water heater – a higher EF means a more efficient water heater. Manufacturers will no longer produce units that do not meet the new standards. Products manufactured prior to April 16, 2015 can continue to be purchased and installed.
What is the new regulation for 20-55 gallon water heaters?
Both gas and electric water heaters between 20-55 gallons will have more insulation. This means they could be up to 2 inches taller and wider. If water heaters get bigger, then some units might not fit in current installation sites. (e.g. small closet)
What is the new regulation for water heaters over 55 gallons?
Both gas and electric water heaters will have unique installation requirements. Gas water heaters over 55 gallons will use a new condensing technology. Electric water heaters over 55 gallons will be required to use heat pump technology, which calls for the installation of a condensate disposal line, and the provision of sufficient air volume to accommodate the heat source, which may prevent installation in smaller spaces.
courtesy of: http://www.homecarebuzz.com/