Re: water pressure low
If that polybutene tube on the water heater has a smaller ID than the pipe that was there it will act as a pressure reducer for the hot water.
You don't say if he has city water or a well. If he has a well the pressure switch may have been replaced with one with a lower on/off setting. Off the shelf they are usually set for 20/40 or 30/50. You can remove the cover and inside should be instructions on increasing the pressure. It will be either a one screw adjustment or a two screw adjustment.
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