hot water tank problems... kenmore power miser

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!!

You may be better off by using the drain valve on the tank to rinse out the sand periodically than relying on a filter. Precipitated minerals can look like sand, and the filter may not do much except create a new maintenance issue and restrict the flow when clogged.

Are you sure you have the hot and cold supply pipes hooked up to the right place? Getting them backwards will shorten the time you can get hot water significantly because of the dip tube. If backwards, instead of drawing water off the top (hottest) portion of the tank, you'd be drawing it from nearer the bottom, where the coldest water is.

A common reason for cool water is from a single handle valve that has a cross-over. This can happen on some valves when the cartridge fails. Whenever you do maintenance on the water supply system components, when you turn the water back on, it can release some debris and clog things up.