Q: I live in a condominium that has a lawn sprinkler system that works in four cycles of about 45 minutes each. After each section shuts off there is a loud clanging noise in the pipes in our apartment, and I am afraid this the plumbing. I have been told there is air in the pipes, but no one seems able to tell me how to get rid of it. Can you suggest a solution?
A: I think your problem is "water hammer." This is not uncommon where there are automtic valves in a system. When fast-moving water is brought to a halt suddenly (by the fast-closing valve) it cannot compress, so it bangs against the pipes and fittings.
The problem is easily solved by installing one or more antihammer devices in the water line -- sometimes one will be enough for the whole system. In your case you will need one near each of the solenoid valves that shut the water off as the system cycles. An antihammer device is an air chamber that is installed by cutting into the line, then installing a tee and screwing the device into the upper, or vertical, leg of the tee.