Water hammer, high pressure, intermittent low pressure
Posted by Debbie Salierno on October 28, 1999 at 19:27:12:

I have a lot of water pressure and hammer/clank problems...

I have a new home in an area that is supplied with high water pressure (125# or more). In the last year
I have experienced these problems, which may or may not be related:
- water hammer (really loud bang) when my first and second auto sprinkler sprinkler valves turn on
- faultly water pressure reducer valve
- occasional warm water in the cold water line of an upstairs faucet (the water heater is in the garage; this is not the closet faucet to the heater but it is not too far)
- if I'm in the shower or have a faucet running when the sprinklers turn on, the water flow stops momentarily

By code I have an expansion tank on the water heater. The plumbing contractor replaced the tank twice and in a short time, the water hammer returned. As an experiment we replaced the expansion tank with an arrestor and the really loud hammer went away. However we just put the expansion tank back on so that I can meet code. For the moment no water hammer, but if previous pattern holds true it will resume after a while. The first two auto sprinkler valves do "clank" though. We replaced them and for a while they were ok, but now they clank again. The third sprinkler valve is always ok. I even changed the order of the valves, and a valve that didn't clank in the 3rd position does in the first or second position.

The pressure regulator valved has been cleaned (didn't help) and finally replaced. Now this replacement reducer valve is not working.

Early on we put a water hammer arrestor in between the sprinkler valves and the water line to the house, but it did not stop the hammer. Only the arrestor on top of the water heater tank solved that, but I've had to put the expansion tank back on.

None of the new houses around me, even those with identical floor plans, do not have any of these problems.

Any ideas as to why the sprinkler valves are causing so much trouble? Would you recommend putting the T to the sprinkler valves before or after the pressure reducer valve ( or is this irrelevant to the problem)?

Is it normal to experience a drop in pressure when the sprinklers turn on (doesn't happen to my neighbors)? Is the intermittent back up of hot water into the cold line related to all of this?

thanks for reading this and for any suggestions you might have,

Hammered and confused,