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Water Heaters Heating domestic hot water for bathing has come a long way in the last 20 years or so. But chances are if you go and look at your water heater right now, you will see a large white cylinder about 5 feet high and 20 inches around. If you have gas it will include an energy-wasting flue and if you heat water with electricity you probably pay 2 to 3 times more for your hot water than you should. On top of this obvious waste, you might consider that an electric water heater, powered by electricity from a coal-fired power plant, generates twice the carbon footprint of a natural gas-fired water heater. The water heating industry uses an energy factor, which is almost as useless as the AFUE rating used by the heating industry. Application and installation or operating efficiency (every bit as important as combustion efficiency) is hard to calculate and thus ignored. But with the standard tank type water heater there is little to go wrong; little to do to improve efficiency. You are stuck with about 35% of the fuel you burn to make hot water going up the chimney instead. The good news is is that conventional water heaters only last about 10 years, so you are liable to get a chance to replace yours very soon! High efficiency water heaters Of course a water heater has to condense to be considered high efficiency. In this catagory we are left with Polaris tank style from American Water Heater and the new Navien tankless style from Korea. Both excellent-if pricey-alternatives to conventional water heaters. Tank-less water heaters All the craze these days, many enthusiastic customers call to inquire about this "Green" solution. I am an advocate in fact, but the combustion efficiency of a tank-less water heater is very close to a conventional water heater (80%). The savings then must come from eliminating a hot tank of water, connected flue and the standby losses that occur thereby - perhaps 5% of the total. With limited output and no standby for peak loads, care must be taken in order to fit a "tank-less" to the American lifestyle. This is particularly true of our more northern climes where domestic "incoming" water can be very cold in winter. The Japanese and Germans are quite familiar and comfortable with 'point of use' tank-less water heaters. I design systems for individuals and commercial concerns all the time with great results! By the way, tank-less water heaters will last about 20 years properly applied and installed for residential use.
Indirect water heaters One of my favorite ways to make copious amounts of domestic hot water, without compromise. Coupled with a Mod-Con boiler the indirect water heater acts as a huge thermos bottle, super insulated, lacking a fuel wasting flue and capable of utilizing the full output of your space heating boiler for - as they like to say - endless hot water. By integrating your comfort system you can afford to buy the best and most efficient boiler available and use it to heat water, floors, radiators, fan coils, sidewalks.... well you get the idea. Expect an indirect water heater to last over 20 years!
"But I don't want to run my boiler in the summer time!" Well, even though domestic hot water demand is important (25% of a home energy bill) and water is usually stored for peak loads, the time it takes to make say 50 gallons of hot water for bathing etc. is typically 20 minutes (hardly enough time to overheat the basement). Consider further that we will be storing this heated water in a super-insulated storage tank lacking an energy wicking flue pipe. Combination water/space heaters Bradford White makes the most popular combination water/space heater known as the Combi1. I like them, though they are pricey and only 82% efficient, they have the distinct advantage of providing space heating and domestic hot water in one neat package that can usually replace an existing water heater with a minimum of labor. In smaller homes or for "basement only" radiant floors, this is the unit I often use. http://www.bradfordwhite.com/products2.asp?id=13&product_id=92 | Before 65% efficient  | After 95% efficient with hot water!  |
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