Using Fixed BTU Input Water Heaters to Satisfy Variable Hot­ Water Demand Wastes Energy!

by Product Support Team; Bock Water Heaters, Inc.

Wasted Energy

What would happen if you had a car that could travel at one speed only,it couldn’t travel faster or slower? The likely answer is that once in a while you would get lucky and your cars speed would be a perfect match for the situation at hand. But,there are many other instances when your car would be either too fast or too slow for the situation then present.

Conventional water heaters are similar in that they operate at a fixed speed only.With water heaters, fixed speed relates to the amount of fuel per hour (expressed as BTU Input/hour) that can be fed into the burner to generate heat from which to raise the temperature of cold water to the desired hot temperature.Similar to the “one speed car” story,a fixed BTU Input water heater operates at full throttle only (maximum rated BTU Input) regardless of how quickly water needs to be heated to satisfy the situation.Heating water more quickly than is actually needed wastes energy.

Water heaters attempt to accommodate for the varying amounts of hot water needed throughout a day by keeping a supply of hot water stored in an internal tank.When a hot water tap is opened,hot water is drawn (i.e. hot-water draw) from the internal tank to the open tap. A problem often arises when it comes to refilling (hot-water recovery) the internal tank. If water must be heated quickly to accommodate a large or continuous hot-water draw,then a water heater operating at its fixed maximum BTU Input may be a good match for the situation.But, not every hot-water draw requires maximum BTU Input recovery – sometimes the majority of draws throughout a 24-hour period require much less than maximum BTU Input. Operating at “full throttle” when maximum recovery is not needed is a significant waste of fuel.

The problem: “hot-water draws are variable and conventional water heaters are not!”

Lower BTU Input Yields Higher Energy Efficiency

As a general rule,”lower BTU Inputs yield higher thermal efficiencies’:Thermal Efficiency is the percentage of energy contained within a fuel (natural gas or propane) that is transferred into
water (i.e.raised water temperature).Just as an automobile typically attains better Miles Per Gallon traveling slowly than it does traveling fast,a water heater typically attains better Thermal Efficiency heating water slowly at lower BTU Input than it does heating water quickly at higher BTU Input.

Modulating BTU lnput the Solution to Variable Hot-Water Draws

The solution to consistently maximizing Thermal Efficiency when hot-water draws are variable is to also have variable (i.e.modulating) BTU input. Modulation technology exists and has been utilized in boilers for many years. Inspace heating applications, modulating boilers are known to reduce energy consumption significantly compared to fixed input non-modulating boilers. Similar modulation technology is built into optiTHERM modulating high-efficiency water heaters.

optiTHERM® (Optimal Thermal-Effidem:y)

optiTHERM gets its very name because it is engineered to provide “optimum thermal efficiency” by treating each hot-water draw as unique. By modulating fuel input according to the unique needs of each individual draw of hot water,optiTHERM is able to reduce fuel consumption compared to typical “full-throttle” water heaters. Scientifically conducted laboratory simulations show that optiTHERM can reduce fuel consumption by 1S% to 2S% compared to conventional fixed BTU Input high or standard efficiency water heaters.

optiTHERM also incorporates the Bock Turboflue® helical fin heat exchanger. This patented technology features hundreds of steel fins welded in a helical pattern to the interior of a heat exchanger tube. The fins act as additional surface area to scrub heat from the combustion exhaust, while their arrangement in a helical pattern creates turbulence in the air stream to direct the exhaust through the fins.

optiTHERM dual-stage Turboflue heat exchanger and 3rd pass condensing tubes are maintenance­ free, never needing cleaning,unlike some coil-type heat exchangers that require periodic removal and cleaning – an expensive and interruptive procedure.

Together, optiTHERM modulating burner and ultra-efficient Turboflue helical fin heat exchanger minimize fuel consumption,saving fuel and saving you money.

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