Our old oil water heater began to leak about three weeks ago. I ordered a KenmorePower miser 12 electric 272.5 litre from Sears. By the time it made it here last Sunday the oil water heater was leaking huge amounts. We installed the new tank. When we were moving our old tank We discovered it was about half a foot full of sand from our well. My husband installed a Rainfresh BH010 filter to try to reduce the sand in the new water tank. Everything seems to be installed properly but when we turn on the taps (sinks, bath or shower) on our upper level, there is hot water for about 30 seconds, then lukewarm water, then cold. It seems to stay hot in the kitchen and downstairs powder rooms. Anyone have any ideas?? Please help!!