Canadian well is a geothermal well system which uses earth temperature to heat or to cool a house. Canadian well is known as puits Canadien or also puits provençal in french. The main principal of the canadian well is to absorb earth temperature during summer and supply fresh air to the house and supply the relatively hot air in winter.

This phenomena is shown in the figure below:

The VMC pipes are used to absorb the earth temperature. Earth has the temperature of a range 12-14°c only at some depth. So as to absorb this temperature  pipes must be at least 1.2m.

However this principal can be used for big house using the parallel pipes to absorb maximum earth temperature as shown in the figure below:

How it works:

In summer it absorbs the earth temperature of around 12°c in order to diffuse fresh air to house. In winter the exterior temperature is either negative or far less than 12° and this system is highly efficient as it brings the air negative temperature to 12°c.  As the average temperature for comfort in France is 19°C we don’t need to install big heaters to heat the air of 12°c to 19°c. The free earth energy is absorbed and the consumption of expensive electricity is thus reduced. This system is very useful for the people who have allergy to dust.

In order to absorb maximum earth temperature the pipes must be at least below 1.2m as I said before and the length of the pipes usually used is 40m anyway the longer is better. The air velocity must be very low (2.5m/sec) and the diameter of tube  between 15cm and  60cm. The slope of pipes must be less than 2% to assure the best air flow and the radius of curvature less than 50cm.

The best position of end of the tube can be your garden to absorb a fresh air by the tube as shown in figure: