ARETHA Costa del Grillo


I’m proud to announce that few days ago we officially started the ARETHA Costa del Grillo, the third and the first productive prototype of ARETHA system.

ARETHA means AiR Exchange THermal Assembly and is a new simple, light and cheap Flat Plate Solar Thermal Collector without water inside.

The idea of ARETHA came to my father, FRANCO MANTEGA, who is a retired nuclear researcher. He observed that there are a lot of demolished cars everywhere, and each one of them has a probably still running radiator, which is one of the best water/air heater exchanger. The thermal exchange power of a car radiator is based on the maximum power of the engine, which means that a medium car has a radiator exchanging more or less 100 KW; so much power in a very little space and weight.

The questions that my father was asking himself were: how many copper pipes are needed to exchange the same heat of a radiator? And, how much is the weight of the pipes full of water compared to a radiator. And last but not least: what about the costs?

So Franco begun to build at home the first prototype of ARETHA: a little 1 m2 plate where inside there are only air, a radiator and a fan. Like every first prototype, the ARETHA ONE was full of defects and needed improvements but overall results have been positive. Therefore Franco did a second step in his research: find a scientific help which would confirms his ideas.

So, in collaboration with the Politecnico di Milano University and CISE 2007 (a scientific community mainly formed by former researchers), Franco build the second prototype, bigger than the first one, full of sensor and with a live connection to the internet.

The results and the improvements originated by the ARETHA CISE 2007 were used to build the third and the first productive prototype of ARETHA Solar Thermal Collector: ARETHA Costa del Grillo.

The Costa del Grillo Farm has mainly three zones: the fields and woods, the living zone down there and the horse zone, where we are, which includes paddocks, a little barn, a saddlery and a Club House with a small kitchen and a toilet. Since the beginning, the horse zone had its own solar power and it is not connected to the electrical network. Till yesterday the water for the services in the Club House was only cold.

This characteristics were a big opportunity for my father’s projects.

In the late springtime we started to build a shelter for washing and shoe horses. Its roof was a good place where to lie ARETHA and the hot water produced would be used in the Horse Zone.

ARETHA is divided in three parts: the primary circuit, the secondary circuit and the controller. As components of the primary circuit there are a tank, that was insulated with straw, a pump, a panel with a radiator, a fan and some pipes.

The secondary circuit brings the cold water into the tank and gives back hot water ready to use.

The controller checks the panel temperature. When the temperature is grater then the tank water, the controller starts the pump and use the fan to keep the panel temperature constant in order to save energy. I built the controller with Arduino which is an open source platform very flexible and customizable.

ARETHA will be at MAKER FAIRE ROME from October 3 to 6, 2013

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