Easy fix for water hammer
Bleed system to stop clanging pipes
June 24, 2009
By Bill and Kevin Burnett
Inman News®
Once again it's time to empty the question bag. Today it's a bit of a hodgepodge. Water and electricity usually don't go together, but today is the exception.
Q: We must have air in our plumbing pipes, because every time we turn them on and then shut them off there is a big bang. After searching online for "air in pipes," I have discovered that we have a water hammer problem. The loud noise occurs only when we shut off any sink, or the dishwasher stops. Do you have simple, easy-to-follow instructions on how to get rid of the water hammer?
A: Maybe. Water hammer is hydraulic shock. It's the sudden increase in water pressure in the pipes when there is a change in the direction or velocity of the water. Water is not moving in the pipes when all the valves in your water system are closed. The pressure is constant. When a faucet is turned on, the water flows. Depending on the water pressure, it probably moves at a pretty good clip.
When you turn off the faucet, the water flowing in the pipeline suddenly stops. The result is the transfer of energy created by the flowing water to the pipe walls, making the pipes shudder and vibrate. The pressure wave bounces back and forth, hitting the sides of the pipe until it dissipates because of friction. The pressure wave causes the banging you hear.
Try this simple fix: First shut off the water to the house at the main shutoff valve. That could be at the water meter. Next, open all of the faucets (sinks, showers and tubs). Go to the lowest water outlet. It will usually be a hose bib, but could be a laundry sink in a basement. Drain the system of water.
When all of the water is out of the system, close all of the faucets and turn the water back on to the house. With luck, it will eliminate the water hammer. Be careful when turning on the faucets, as they will spit air until the water refills the pipes.
(Our reader followed these steps and her water hammer is only a memory.)
Q: We have an argument over which way to properly install a standard two-outlet electrical receptacle: with blades up and the grounding pin down, or round pin up and both blades down?
I'm under the impression that electrical codes have changed in the past 10 or 15 years. With the two blades up it would be possible for something to lie across the blades, thus shorting out the socket. The grounding plug being on top would prevent this.
A: This is a new one for us. We've been doing our own electrical work for almost 30 years. We've never had an inspector or an electrician comment on whether plugs should be installed with blades up or blades down. We've installed plugs both with blades up and down -- and sometimes sideways -- and the work has always passed.
But given the choice, we usually install them with blades up because we think it looks better. We've done a little research and haven't come up with anything definitive one way or another. So no one wins the argument. The choice is yours.
As for something falling across the blades, that's a remote possibility. Just push the plug in all the way. If something should contact the hot side and the neutral side of the circuit at the same, all that will happen is that it will trip the circuit breaker.
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