Plumbing Question 101
Question:
I have asked every plumber I know and they have never heard of such a thing as this. My entire water system is 3/4 copper except where it branches to fixtures.
Main shut off is a ball valve in basement feeds into a PRV and on into the to the house. Every now and then, we will get a water hammer like sound when we flush the toilet or the dishwasher calls for water. After that our hot water flow is a dribble; cold is still normal. When a faucet’s hot side is initially opened there will be pressure for a second and then it slows; the cold side is still normal pressure. The only way to get it back is to tap the vacuum breaker on the hot water tank and expel some water. It will operate for awhile again for a day or so and then return. I’m totally at a loss on this one. Any ideas on it’s correction is appreciated.
Answer:
Since the cold side is working with no problems we can assume the problem is on the hot side. How old is the water heater? You may have sediment built up in the water heater if it is more than 5 years old. Sediment from the water heater could cause the water to trickle and even the water hammer. Also check to make sure the valve is open all the way on the heater inlet. Sometimes gate valves or multi turn valves will get stuck partially closed and draw air into the line which will cause water hammer and drop in pressure.
Some water heaters have a little ball that floats up and down on the hot nipple that come with the heater. It is suppose to drop down and keep the heat in the tank and flow up when water is running. I would cut that nipple out and replace it.