At Sunteq we have developed several significant innovations to ground loop installations and consequent manifolding of the loops that allows purging to proceed with relatively few problems. Deaeration is not a phenomonen that requires only hours to complete. In fact, it can require weeks, even months to fully purge a ground loop. Three to four thousand feet of piping offers a considerable amount of internal surface area on which air bubbles can adhere.
Where possible, we recommend bringing all individual loop tailpieces inside the structure to be manifolded. The manifold that returns the loops to the field should have each loop valved so that loops can be purged one at a time or two at a time for significantly more effective deaeration. If one or more loops are locked-up, the installer will know instantly.
Air in the loop water
Air is a constant problem to reliable loop operation. Air can cause “air-locking” which prevents the pump from circulating the water through the loops. But air also inteferes with effective heat transfer and, in addition, can cause corrosion of the cast-iron pump housings.
Industry methods of dealing with this anomaly do not adequately address the problem.
Debris in the loop water
While theoretically impermissable, debris in the loop water nonetheless occurs. Unless working in nearly clean-room conditions, some debris will penetrate the system. Debris that is abrasive can erode the pump housing and the internal tubing in the heat exchanger.
Sunteq created “Consta-Purge”, the very effective combination reservoir / strainer / air purger that totally eliminates air, constantly cleans the water returning from the loops, and stores excess water so as air purges from the system, water takes its place. In addition the Consta-Purge reservior provides a built-in sight glass that immediately tells the owner when water needs to be added to the system.
How does Consta-Purge deaerate water? Tiny air bubbles in an enclosed piping system will stay entrained in water moving at a velocity of 6 inches per second or greater. Water entering the Consta-Purge Reservoir from the loop manifold piping traveling at a velocity of approximately 44 inches per second is slowed by a factor of ten to about 4 inches per second. Air in the water, being lighter than water (naturally), rises to the top of the reservoir and, since the system is unsealed, out into the atmosphere. Further, the filter media immersed in the water provides enhanced surface area on which the small bubbles can attach and helps trap and release those bubbles so that they are more quickly purged.