efficency of atmospheric steam w/water heating coil?

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  • This topic has 1 reply, 2 voices, and was last updated 19 years ago by Harold Kestenholz.
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    • #275784
      Byron Bennett

      I have an 8 family unit in NYC that needs boiler replacement. It provides steam heat and has a water heater coil. It is currently 400,000 btu. I have applied for a NYSERDA loan that specifies at least 81.5% efficiency for the atmospheric steam and at least 85% for the water heater. I have found that Burnham makes the steam boiler at 82.5% but I need to find a separate water heater for our size building at 85%…any suggestions on sizing and manufacturer?

    • #292882
      Harold Kestenholz

      Check the reading of the loan. Generally, water heaters are not rated the same as boilers in terms of efficiency. A water heater energy factor (EF) difffers in testing procedure.

      An electric water heater will have a very high EF and cost you the going rates for electricity, which in your area is many times that of other fuels per btuh.

      There are boilers that have efficiencies over 85%, enabling you to have one service company take care of both the steam boiler for heat and a boiler to make hot water as an independent water heater to comply with the loan. http://www.monitorproducts.com/FCX.html http://www.aceee.org/consumerguide/topwater.htm

      Energy savings can accrue from having the hot water in the boiler pumped through heat exchanger tanks after the boiler has heated the building, thereby recovering the energy in the hot water in the steam boiler not used to heat the home and ordinarily wasted up the chimney and into the basement.

      Energy loans are often affected by ‘special influences’ with clout such as utilities and manufacturers who can influence the legislature to create special rules in equipment selection that ‘look good’ but do not save money and energy in the long run. As water heaters rarely have efficiencies over 70 percent, so are given EF’s which hide that rating, this is one of those areas. You could have high EF water heaters installed that will cost you the entire loan to the utility within 5 years and become a money drain from the rentals thereafter.

      An electric heater can cost you three to four times that of a fuel-burning appliance.
      Everything else being equal, select a water heater with the highest energy factor (EF), the measure of a water heater’s efficiency. EF is
      based on recovery efficiency, standby losses, and cycling losses. The higher the EF, the more efficient the water heater. Electric-resistance water heaters have an EF ranging from 0.7 to 0.95; gas water heaters from 0.5 to 0.6, with a few high-efficiency models at around 0.8; oil water heaters from 0.7 to 0.85; and heat-pump water heaters from 1.5 to 2.0.

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