Water hammer

**Hobo Bill** · 02-13-2021, 02:44 PM

2019 Reflection 337RLS. Last couple of weeks hearing a clunking noise - clunk clunk - when I turn on water - either hot or cold, or toilet. I am full timing in the same place for the last few months and on city water. Sound coming from behind the hutch where the hot water tank and water panel is. Doesn't happen every time, only happens a few times per day. Sounds like water hammer from taking in air somewhere, but I don't know where that would be from. Any ideas ??

**Second Chance** · 02-13-2021, 02:55 PM

"Water hammer" happens when you turn the water off abruptly. Is the sound happening when you turn the water on or off? Also, air is more compressible so usually reduces water hammer - that's why many plumbers put the little capped-off pipe above the faucet manifold for an air trap. On the other hand, sometimes reducing the pressure in the hot water heater will cause some air bubbles to rapidly form. That's usually a one or two second sound rather than a single "rap."

Rob

**Hobo Bill** · 02-13-2021, 02:58 PM

Originally Posted by Second Chance

"Water hammer" happens when you turn the water off abruptly. Is the sound happening when you turn the water on or off? Also, air is more compressible so usually reduces water hammer - that's why many plumbers put the little capped-off pipe above the faucet manifold for an air trap. On the other hand, sometimes reducing the pressure in the hot water heater will cause some air bubbles to rapidly form. That's usually a one or two second sound rather than a single "rap."

Rob

Happens as soon as I turn on the water. It goes clunk clunk, just as you would say it. No other strange noises.

**Second Chance** · 02-13-2021, 03:08 PM

Originally Posted by Hobo Bill

Happens as soon as I turn on the water. It goes clunk clunk, just as you would say it. No other strange noises.

My guess is, then, that it's expansion in the hot water heater. If that's the case, it's nothing to worry about. Is the water pressure at the park high and are you using a water pressure regulator?

Rob

**AZMike** · 02-13-2021, 03:19 PM

Originally Posted by Hobo Bill

Happens as soon as I turn on the water. It goes clunk clunk, just as you would say it. No other strange noises.

I've had it happen with old (especially hot) water faucets with bad gaskets/washers. In fact, it's happening now in the bathroom that I haven't gotten to remodel yet.

**Hobo Bill** · 02-13-2021, 03:22 PM

Originally Posted by Second Chance

My guess is, then, that it's expansion in the hot water heater. If that's the case, it's nothing to worry about. Is the water pressure at the park high and are you using a water pressure regulator?

Rob

Yes, using a water pressure regulator set at 45 psi and yielding 45 psi. Campground pressure ranges from 50-60. Would the expansion of the hot water heater also be as a result of flushing the toilet ? Thank you for your help and if you have other questions or comments let me know.

**Second Chance** · 02-13-2021, 03:32 PM

Originally Posted by Hobo Bill

Yes, using a water pressure regulator set at 45 psi and yielding 45 psi. Campground pressure ranges from 50-60. Would the expansion of the hot water heater also be as a result of flushing the toilet ? Thank you for your help and if you have other questions or comments let me know.

Yes - if it causes a drop in pressure on the input side of the water system. If you watch the gauge on your pressure regulator while someone opens a cold faucet or flushes, you'll probably notice a dip in the needle.

Rob

**Hobo Bill** · 02-13-2021, 04:07 PM

Originally Posted by Second Chance

Yes - if it causes a drop in pressure on the input side of the water system. If you watch the gauge on your pressure regulator while someone opens a cold faucet or flushes, you'll probably notice a dip in the needle.

Rob

Yes, you are right, hot and cold is all "connected" at the front end. I will check that with my pressure gage. Thanks

**CoChris** · 02-13-2021, 10:39 PM

Originally Posted by Hobo Bill

Yes, you are right, hot and cold is all "connected" at the front end. I will check that with my pressure gage. Thanks

I think Rob @Second Chance has you on the right track. But if that does not pan out, any chance you have your water pump turned on? My thought is when you first turn on the water, the pressure drops for a minute and the pump kicks in. Then pump turns off as soon as the pressure comes back up. Definitely a low possibility but wanted to toss it out there.

Chris

**traveldawg** · 02-14-2021, 07:11 AM

Isn't there suppose to be some air space in the water heater such than when it is filled there is some air in the top of the tank to allow for expansion? Isn't there a particular way to fill the water heater to establish (or re-establish) that air pocket? Could lack of an air pocket cause the noise?

I like the idea about the pump being on.