I am getting water hammer when someone turns off the taps in the upstairs bathroom in our 2 storey house. They are single lever taps on the vanity sink and a single lever tup control – both made by Delta. I try to gently turn them off but my family is not so careful. I often hear it while sitting at the dining room table having my morning coffee. It sounds like it is coming from the basement but I haven’t tracked it to source. I have experimented with expansion chambers made up from 3/4 copper pipe but don’t seem to have improved matters much. Any advice on location or sizing? I believe it is supposed to be best if they are close to the taps that cause the problem but that is difficult to add in a finished house. Can this be overcome with a larger expansion chamber located in the basement? I am wondering about using a pressure tank with a bladder like used on water systems with a well etc. in the main line somewhere. Alternatively, something larger like 1 1/2 pipe instead of 3/4. Advice from those with real experience will be really appreciated.
Randy
Replies
Many homes already have anti-thump devices (anything from a verticle column of pipe to one of the fancy jobs with the rubber diaphram); but, apparently they stop being effective after a couple of years unless you completely drain the system once in a while to restore the air to the device (the "air" slowly gets absorbed into the water).
If there's no current protection, you can add an anti-thump column to the lines (you have to do hot and cold lines) in the basement and it will give you some relief.
Phill Giles
The Unionville Woodwright
Unionville, Ontario
First hammer arrestors need to be near the point of use to be effective. That is where the water stops and you need a "shock absorber" to handle the water flow when it is shut off suddenly.
The cap'd t's work, for a short time. But the air will be absorbed by the water in a few months.
But they make units with either a small diagrpham (about the size of a softball) and ones with a sealed piston. They start at about $10.
But water hammer from manually operated valves is not common. I would check for excessive water pressure, loose pipes, and worn/loose faucet parts.
Phill and Bill both give good advice.
Check your water pressure, see if it has changed recently. Not likely if you're on your own well, possible if you're on a town/city line.
Then I'd turn off the valves under the sink and disconnect the lines coming out of those same valves. Open the tap to help the water to drain. If you do have hammer arrestors that have become water-logged, this should drain them. Hitch up the plumbing and see if there's a difference.
Plumbing sounds can sometimes be hard to track down, and the location of the sound may not neccessarily be co-located with the problem that is causing the noise.
Don't tinker too much with the expansion chamber in the basement without knowing what and why it does what it does.
Would these be the 1/4 turn disc valve type of valve? I just install some in a house and the hammering started! Turns out you could only turn off the old faucets slowly (many turns), the new faucets 1/4 turn and its a slam shut!! Spent 2 days cliping down the pipes, air chambers and the like. Never did cure it 100% but got close. Clipping the pipes worked the best.