As with everything, laying the ground loop needs planning. The trick is to arrive back at the entrance/exit point to the house with the right amount of pipe. For the 1st loop I use a combination of a single pipe in a single trench and the method Ice Energy call "slinky" which involves loops of 1m diameter 0.5m apart. The latter method obviously requires a wider trench (1m) but (using Pythagoras) you can lay 4m of pipe per linear meter. This is a more efficient use of the ground available. After some careful calculations I conclude that the 2nd loop must be all "slinky".
The basement manufacturer (ThermoneX) came out within 24 hours to take a look. It turned out not to be a leak but a lack of ventilation. The room is completely sealed and there is no movement of air at all. A call to ADM who supplied the ventilation provided a solution - move the air inlet from the other end of the basement (the utility room) to the store room. This should generate a constant airflow from the store room to the utility. The necessary parts have arrived and will be fitted next week.