So in the kitchen I have a faucet with small water heater under the sink. It is always connected to electricity but works only to support set temparature, so just from time to time. When heater starts working, faucet starts dripping for up to 10 seconds, and it is getting worse everyday. Also, when I turn on just the hot water and then turn it off, the water just keeps going for couple of seconds.
The faucet has three pipes: one for incoming cold water from the house system, one for outcoming cold water to my heater, and one for incoming hot water from my heater.
The heater has a small tank, about 1 gal, but there is no relief valve. The only places for air and water to come out are two pipes for cold and hot water.
Hot water from the heater goes directly to the faucet, so doesn't have separate faucet. The faucet itself is regular, with one handle to be turned left/right to get hot/cold water.
What do you think the problem is about? The faucet or the heater? Can I do something without plumber's help?