Drain-Water Heat Recovery<br />Why would you pay for heat only to let it go down the drain? <br />
Whether washing clothes by hand or letting the machine do the work, the water going down the drain contains a lot of heat energy.<br />For homeowners, this wasted heat energy costs several thousands kroner per year. <br />For a business (school), it can add up to more than tens of thousands of kroner.<br />
Howdoesitwork? <br />Drain water flows through a spiral tube; this warms the tank water, which rises to the top. Water heater takes preheated water by circulation through a coil at the top of the tank.<br />
Benefits<br />Saves up to 40% on water heating costs!*<br />Maintenance-free and has no moving parts to break down.<br />Is environmentally friendly, reducing the energy consumption by five to 10%.<br />Reduces greenhouse-gas emissions.<br />* Heat-RecoveryWaterheatinghttp://gfxtechnology.com/HR3-7-1.PDF<br />
Data<br />Aftersampling 15 out of 200 studentstheresults show thatanaverage of 1.13 washes per personeachweekare done 200*1.13=226.6 washes per week. <br />Thewashing machine takes 0.25 kWh per kilogramof clothes. Anaproximation of 5-7 kilograms are washedeach time<br /> 0.25*5=1.25 kWh 0.25*7=1.75 kWh<br />
For 230 washesbetween 287.5-402.5 kWh are used. <br />Thecost of each 1kWh is 0.50 kr:<br /><ul><li>287.5 kWh (0.50)=143.75 kr
402.5 kWh (0.50)= 201.25 kr</li></ul>Assumingthatthe machines are used 9 monthseachyear:<br />5545kr <br />7765kr <br />
Accordingtoinvestigationsthissystem can save up to 40% of thecosts. <br />5545kr saving 40% =2218kr.<br />7765kr saving 40% =3106kr. <br />
FINANCIAL ISSUES<br />Costs<br /><ul><li>Between 2145 and 3580 kronerper system.
Withthesaving of 2218kr-3106kr theinvestmentwouldberecovered in oneyear. </li></li></ul><li>CONCLUSION<br />Ifthesystemisapplied:<br />Thecollegewillsavemoney (3000 kr per year, afterthefirstyear), and energywillberecycled. <br />Itwouldcontributetoourgoal of an eco-village. <br />
ALTERNATIVE OPTION<br />If for certain reasons the system can’t be applied in Uncle Tom’s Cabin, we recommend the College to use it in the new Leirskule building as a general system. It would be minimize the waste of energy through dissipated heat. <br />
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