Why would you pay for heat only to let it go down the drain?

Drain-Water Heat Recovery

• Whether washing clothes by hand or letting the machine do the work, the water going down the drain contains a lot of heat energy.

• For homeowners, this wasted heat energy costs several thousands kroner per year.

• For a business (school), it can add up to more than tens of thousands of kroner.

OUR PROPOSAL

• To implement “Drain-water heat recovery” in Uncle Tom’s Cabin, using the hot water used by the washing machines.

How does it work?

• 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.

Benefits

• Saves up to 40% on water heating costs!*• Maintenance-free and has no moving parts to

break down.• Is environmentally friendly, reducing the

energy consumption by five to 10%.• Reduces greenhouse-gas emissions.

• * Heat-Recovery Water heating http://gfxtechnology.com/HR3-7-1.PDF

Data

• After sampling 15 out of 200 students the results show that an average of 1.13 washes per person each week are done 200*1.13=226.6 washes per week.

• The washing machine takes 0.25 kWh per kilogram of clothes. An aproximation of 5-7 kilograms are washed each time0.25*5=1.25 kWh 0.25*7=1.75 kWh

• For 230 washes between 287.5-402.5 kWh are used.

• The cost of each 1kWh is 0.50 kr:287.5 kWh (0.50)=143.75 kr402.5 kWh (0.50)= 201.25 kr

• Assuming that the machines are used 9 months each year:– 5545kr – 7765kr

• According to investigations this system can save up to 40% of the costs. – 5545kr saving 40% =2218kr.– 7765kr saving 40% =3106kr.

FINANCIAL ISSUES

• Costso Between 2145 and 3580 kroner per system.oWith the saving of 2218kr-3106kr the investment

would be recovered in one year.

CONCLUSION

• If the system is applied:– The college will save money (3000 kr per year,

after the first year), and energy will be recycled. – It would contribute to our goal of an eco-village.

ALTERNATIVE OPTION

• 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.