water pipe hammering

[David Klein]

Got a question for the experts. For some time now we have had pipe hammering when we do laundry and when we flush toilets. I have tried shutting off the main water valve and flushing toilets and draining water lines by opening up the faucet cold and hot with water line shut off. The hammering will stop for a little bit when I flush toilet but then eventually go back to hammering again. I am afraid the hammering will cause issues after a while. When washer is running it I can really hear the hammering. my basement is where the hammering is but my basement ceiling is also finished so I can't get to these pipes to look at them.
Any ideas of what my options are?

Thanks
Dave

 

[Jeff Handy]

Hammering often happens when quick-closing valves shut off.
Like a washer or toilet, and even modern single handle faucets for sinks or showers.

Water is moving and then comes to a dead stop, and the weight and momentum will shift the pipes.

Sometimes it is due to loose or failed clamps on the plumbing pipes.

Sometimes it is when plumbing pipes move a little, and bang on each other or something hard right next to them.
Like a drain pipe, gas pipe, furnace, whatever.
If you can find pipes almost touching, you can stuff cardboard or foam pipe wrap in the gap.

If you can’t see what is banging and making noise, you have to either start opening things up to hunt for the loose pipes, or try to minimize the water hammer situation.

You can install water hammer arrestors on the valves for the washer and toilets.
Ideally they should be hidden in the wall, but they can be exposed if done neatly.
They are short cylinders that have a trapped air chamber inside, to act like a shock absorber.

Sometimes, adding an expansion tank at the water heater will also act as a shock absorber.

 

[Jeff Handy]

Here is what can go by your washer, one each for hot and cold.

They make similar add-ons to attach to a toilet shutoff valve.

3/4 in. FHT x 3/4 in. MHT Copper Water Hammer Arrestor for Washing Machine

https://www.homedepot.com/p/308601314