Efficient tank set up in regards to Supplemental Supply
In our last month’s newsletter we already touched the Importance of the Pre-charge of Pressure Tanks with special focus on reasons for tank failures. This time we would like to focus on the efficiency of the tank. The effective volume in operation is reduced by the amount of supplemental water. This Supplemental Supply will mainly always remain in the tank. It is caused by a precharge which is lower than the cut in pressure. The bigger the difference between precharge and cut in pressure the bigger will be the amount of Supplemental Supply (compared with a system with either the same precharge or the same cut-in pressure). Due to the facts that this Supplemental Supply will mainly always remain in the tank during regular cycles. Due to the fact that water is not compressible it reduces the amount of air available for compression and as a result the tank will act like a tank which is smaller (by the amount of “Supplemental Supply”) than the actual tank. The purpose of having this Supplemental Supply is to bridge the time from detecting the cut in pressure to the actual delivery of water at the tap. The starting time of the pump will delay the water delivery. The supplemental water bridges this gap. Due to this fact we advise for tanks installed with a pressure switch controlled pump with a differential pressure set up to 2 bar (30 psi) to set the precharge 0.2 bar (2 psi) below the cut-in pressure, which will ensure that effective tank volume is not wasted and at the same time some supplemental water is available if needed during the starting time of the pump.