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Old 01-15-15, 02:23 PM   #8
buffalobillpatrick
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Join Date: Mar 2014
Location: Florissant, Colorado
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Geothermal heat pump system at Mt Best

"The crucial part of a heat pump system is the source of heat. In our case it is 10,000 litres of water stored in pressurised underground tank.

In winter, we take heat energy from this water (we cool it down) and deliver this energy at a suitable temperature to the house interior.

Water in the tank is heated by two sources: the Earth interior and our custom made low-temperature polyethylene solar collectors.

Why is this system energy efficient?

To begin with, the system is designed (with Dr Mirek Piechowski from MP Energy Consulting, who holds a PhD in thermal sciences) to operate at very low heat source temperatures (4-10°C).

In this temperature range, the planetary interior actually heats up the water in the undergound tank, because underground soil temperatures are higher. We turned heat storage loss into heat gain. Isn't it intelligent choice?

Secondly, during sunny winter days our solar collectors warm up our 5°C water to higher temperatures, even on partly cloudy days.

Since solar collectors operate at very low water temperatures (5-10°C), heat losses due to convection are minimal. On a sunny winter day we once managed to capture 57kWh from our 24 m² collectors. Who needs fossil fuels?

Thirdly, our heat pump has COP (coefficient of performance) between 4 and 6 in the temperature range of our heat source.

It means that for every 1 kWh of electricity we use to run the heat pump, we transport 3 to 5 kWh of heat from the underground water tank to the house interior."
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