Upon returning from a trip and turning the water back on, we discovered that the hot water line to the kitchen sink and the dishwasher has low pressure. How do we find what is causing this?

speedball1

The first thing you must do is to trurn off the water under the cabinet and open up the faucet and check the inlet ports of the cartridge. Also, unscrew the aerator from the spout and check and clean the screens. While you have the faucet apart turn the hot water back on to flush out the supply. That should get you pressure back on the sink.
The dishwasher has a screen located in the inlet. Unscrew the connection and check and clean the inlet screen.

Now, as to what caused all this. Do you flush your heater on a regular maintenance schedual? No? Let me show you how to flush your water heater and keep mineral buildup outta yo pipes. For long life and fewer troubles you should keep your heater clear of mineral build-up by flushing on a regular schedule. Attach a hose to the boiler drain at the bottom of the tank. With the pressure on, open the boiler drain and let it run untill the water runs clear. You will see a spurt of red,(rust) followed by white or yellow grains,(lime or calcium carbonate). This shouldn't take more then a few minutes. Do this monthly to keep it clear. Now flush out your hot water lines on ALL fixtures that are affected . Now pull each aerator and clean the screens. Be sure you put them back togather the same way you took them out. Don't forget to flush it out every month. Your heater will thank you for it. Hope this helps, Tom