What Causes Repetitive Water Hammering?

Users who are viewing this thread

jimolson

New Member
Messages
4
Reaction score
0
Points
1
Location
Indianapolis
I have a condo with a 10 year old, 40 gallon electric water heater. I have city-supplied water. Obviously I'm due for a new water heater real soon. I live in a region with very hard tap water.

Whenever a water valve is open in the condo (toilet, sink, or washing machine) there is a repetitive banging sound coming from the walls. I can also hear the sound in the water heater. The repetition rate is roughly 2-3 Hz. Some days the sound is so loud you'd think my neighbor is pounding on the walls with a hammer.

Someone at the local water company suggested to me that the problem is due to an air bubble in the water heater arising from calcification of the heating element. That sounds plausible to me, but how does an air bubble in the water heater cause pipes to bang?

What is the device in my house that is opening and shutting repeatedly and causing the banging sound?
 

Jadnashua

Retired Defense Industry Engineer xxx
Messages
32,770
Reaction score
1,190
Points
113
Location
New England
Make sure that the main shutoff valve is fully opened. Do you have a PRV? Does this happen with both hot and cold, or only one (and if so, which)? Have you checked the water pressure?
 

LLigetfa

DIYer, not in the trades
Messages
7,497
Reaction score
575
Points
113
Location
NW Ontario, Canada
I have seen where loose fitting washer-style faucets would oscillate up and down like a jackhammer air motor does but that produces a sound like a woodpecker, much faster than 2 - 3 Hertz. If the sound is prevalent at the water heater, I wonder if it doesn't have an anti-perc device. My water heater has an anti-perc that makes loud clunks, but it only does it at the start and end of the water flow. Some water heaters have a mixing valve on the outlet that blends some cold to reduce the temp of the output. I'd look for some such thing as well.
 

DonL

Jack of all trades Master of one
Messages
5,205
Reaction score
72
Points
48
Location
Houston, TX
Hello Jim and the Group,

Jim if it is in a Condo then it could be problems with anything within your building.

I would recommend contacting the Maintenance Person for Your condo and have them check it out.

If You pay for Condo Fees , Then Maintenance should fix it.

Sounds like others could be having the same problems.

Are any of your neighbors having the same problem ?

Maybe its that neighbor lady wanting you to come over. lol.

Have a Great Day.
 

jimolson

New Member
Messages
4
Reaction score
0
Points
1
Location
Indianapolis
Repetitive Water Hammering: Problem Resolved

I resolved the problem I posed to the forum last week. When I removed the 39 gallon low boy electric water heater it gave me better view of a tight nest of copper piping secluded in the closet wall behind it.

The nest of pipes included a pressure regulator/reducer. The regulator appears to have been installed ten years ago when the water heater was replaced. This regulator is the source of the 3 Hz oscillation.

When I adjust the screw on the front of the regulator, the frequency and intensity of the oscillation changes. I think that counter-clockwise adjustment of the pressure setting screw is the preferred direction, likely reducing the output pressure.

I verified that the street valve is completely open, as is the mains valve in the condo.

The water flow rate that triggers oscillation is quite low. Flushing a toilet is sufficient.

Is the regulator oscillating because of lime build up in it? A pebble wedged into it?

The suggestion that the problem was an air bubble in the water heater appears to be wrong. A new water heater did not affect the problem.

By the way, there's an amazing amount of pea gravel-like stuff that washes out of a ten year old water heater when you up-end it in the driveway.
 

Jadnashua

Retired Defense Industry Engineer xxx
Messages
32,770
Reaction score
1,190
Points
113
Location
New England
The PRV may be shot at 10-years. Also, when a PRV is installed, you also need an expansion tank. You can buy an inexpensive water pressure gauge for around $10. Get one with a peak reading hand (tattle-tale) and install it and leave it for say 24-hours. Note what the peak reading is, and your current value. It is generally recommended to install a prv when the pressure exceeds 80psi.

If you flush the water heater periodically, you'll remove a lot of that mineral buildup and it will work better, longer.
 

Ballvalve

General Engineering Contractor
Messages
3,581
Reaction score
45
Points
48
Location
northfork, california
Moral of story - Do not hide PRV valves. Install a full bore valve in the weater heater clean out and use a coat hanger or vacuum adapter every few years to suck the calcium out. Then change the anode every 5 or ten years.

And dont toss the old rig - its still fine.
 
Top
Hey, wait a minute.

This is awkward, but...

It looks like you're using an ad blocker. We get it, but (1) terrylove.com can't live without ads, and (2) ad blockers can cause issues with videos and comments. If you'd like to support the site, please allow ads.

If any particular ad is your REASON for blocking ads, please let us know. We might be able to do something about it. Thanks.
I've Disabled AdBlock    No Thanks