New Pipe Hammer after installing an Expansion Tank

[WereOutThere]

Hello gentleman, and if your not a gentleman I would still appreciate your weighing in on this... it doesn't make a bit of sense to me.

I just installed a third water heater in our house after a couple water heater failures in fairly rapid succession.

The plumber that installed our first new water heater when we bought the house, did not incorporate an expansion tank into the installation.

I decided I shoud to install the newest water Htr exactly like recommended in the installation instructions, and per code requirements with a new 5 Gal expansion tank.

Or house has copper water distribution lines. We've lived in our house 5 Yrs, and proir to the installation of this new expansion tank we had never heard any pipe hammer.

I installed the expansion tank in the 1" main line within 5 Ft of the new water Htr. Suddenly when turning on the tub hot water proportioning valve in the closest bathroom, there's a new pipe hammer.

Any ideas???

 

[IFIXH20]

Did you open the farthest fixture when refilling the lines with water to blow the air out the system ?

 

[WereOutThere]

Did you open the farthest fixture when refilling the lines with water to blow the air out the system ?

Thx for the reply,

I Did... Opened all the hot and cold water fixtures, once the main was back on and the water heater filled I started shutting off faucets... Thats a water waster!

The proportioning valve on that tub wasn't working at all (wouldn't even run cold water through it) when I had the hot water lines shut down to install the water Htr...

I'm by no means an expert about how proportioning valves are supposed to work, but wondering if it could have something to do with that old faucet proportioning valve???

 

[IFIXH20]

If the valve at the tub is a pressure balance valve the valve has to sense hot & cold water pressure to operate. If you have replaced 3 water heaters in 5 years you have a problem that needs to be address. Something is causing the premature failure and it's being over looked.

 

[WereOutThere]

If the valve at the tub is a pressure balance valve the valve has to sense hot & cold water pressure to operate. If you have replaced 3 water heaters in 5 years you have a problem that needs to be address. Something is causing the premature failure and it's being over looked.

I'm with you, believe me my wife has been beside herself, and we've been without hot water for a total of 9 Wks over the last year! Since you bring it up I'm happy to reitterate the whole sordid affair if it will help diagnose and address this new pipe knock -

I'm in the trades and here's how they work here... The big plumbing Co's will quote you a price, but it's in and out as fast as possible, otherwise it's T&M and anybody's guess.

When we bought our house in 2009 we decided to have the water Htr replaced cause the inspection indicated it was OK but ooold! for expedience I had the new Htr Installed by a local plumbing Co. Frankly the plumber did a pretty mediocre job; Messy modifications of the supply lines, didn't install an expansion tank, didn't plumb in the pressure relief valve, didn't plumb a drip leg in the gas inlet... I rolled with it caus we had tons going on at the time...

Rheem's been good about replacing the water Htrs under warranty, but they don't come anywhere close to covering the service or installation costs; $125.00 to cover repairs, priced at $500.00, $250.00 to cover installation and the Min Cg I could find was $1,000.00. So from here I decided to do the subsequent work myself since I have a fair Amt of experience in the trades, have sweat copper, and am generally mechanically inclined.

The first Rheem had a 7 Yr waranty, and lasted 4 1/2 years. Pilot light wouldn't stay lit. Rheem Tec Assist sent me a new burner Assy, when that didn't fix it, they decided they had sent me the wrong burner Assy, and sent a second. When that didn't fix it they sent me a new control valve. When I was working on it, it was apparent that there had been water in the catch pan, and there was some mild rust around the bottom of the Htr. A month later without hot water Rheem replaced the 1st water Htr.

I installed the second water Htr. Unfortunately that water heater did not work right out of the box, pilot light wouldn't stay lit. When I called Rheem, and was looking closely to describe what was going on to the Tech, I noticed the front plastic cover on the control valve was dented and split, the Tech Assist decided it must have gotten bumped in shipment and sent me a new control valve. That got it up and running. I didn't make any substantantitive modifications to the previous plumbing job described above, but I did install a drain line on the pressure relief valve. The second water Htr failed after 7 Mos. This time it was leaking where the control valve threads into the tank. Rheem replaced the water Htr a second time.

So now I'm on my 3rd water Htrin a year. I decided I better replumb the whole thing as described in the installation instructions, and cleaned up the mess the plumber who installed the first water Htr left. I added the proper expansion tank, re-routed the lines in and out, added a drip leg to the gas line. Worked like a beauty right out of the box!

So that leaves me with this question of pipe knock after I installed the expansion tank???

 

[ExtraMilePlumbing]

Maybe you're water pressure is too high . Buy a pressure gauge and threat it on you're fartest hose bib . pump up you're expansion tank to 5 psi over you're water pressure .

 

[WereOutThere]

Thx for the feedback, can try that!

 

[ExtraMilePlumbing]

Also.go straight to the source . If you're getting a banging sound in you're shower valve then try replacing the shower cartridge or stems. Plumbing works in mysterious ways . Mysterious to the novice but by law to the worthy plumber