I know how to fix a Water Knock in the Cold Water, is it the same for the Hot Water?

[Werz Kit]

I fixed a Water Knock that started about 2 years after we moved into OUR new home (the house itself was not new.) Now we get a knock when turning off the HOT water. Do I fix it the same way - cut off the water, open the lowest drain ( the water hose faucet) then open several fixtures in the house draining the water in the knock arrester. I believe that is right - it fixed the knock in the cold water any way.

But, is it the same for the hot water knock? Or do I need to do something with the water heater to open it to atmospheric pressure?

Any help would be appreciated so I don't screw up the new water heater I managed to install without any cussing or screw ups.

Thanks RC

[Travelover]

Yep, fix hot water the same way - drain it and let it refill trapping air in anti knock pipe.

[hallerb]

first look for loose pipes, try grabbing pipes whil;e someone creates the trouble. might be easier than you think

[Steve]

Travelover wrote on 27 Nov 2007 in group alt.home.repair:

Turn off the water heater before draining it so it doesn't burn out.

See the many other discussions on this list about how to drain a water heater. You may be in for more work than you think.

[Werz Kit]

Ok, I admit I am a poor DIY, but when you say "it" do you drain the pipes or drain the hot water heater?

IF you are speaking of the HWH, can't I just drain it below the emergency relief value and just open that to give the tank Standard Atmospheric pressure? Well, comment on it please, but if I have to mess with the tank, that is what I'm going to do.

Hell, I guess I should have just tried what I did with the cold water first. Then mess with the tank if that doesn't work.

Please comment.

Thanks. R>Yep, fix hot water the same way - drain it and let it refill trapping

[Werz Kit]

If I have to drain the heater, I'll just drain it below the level of the Emergency Relief valve. Then open said valve to atmosphere. That SHOULD work, IF messing with the HWH is the right thing to do.

Ron

[Werz Kit]

I appreciate the advice but the wall are all closed. I have to rip sheet rock. Not that I wouldn't do it, but it would be well behind any easier fix. But thanks for the suggestion.

Ron

[Ron Cliburn]

Steve,

Maybe it is a good thing I didn't read about how to drain the heater. I just put a hose on the drain, ran it through a filter to my pressure and used the hot water to clean the walk. Then let the rest of the water run into the lawn. Opened the emergency valve on the tank to help it drain and all the hot water fixtures in the house. No Problem.

I was planning on just opening the emergency valve and draining it to that point, but then I realized that the hot water enter a pipe on the bottom of the tank, not the top ( or hell I could be completely wrong), so as I said, I drained the entire tank.

The hardest part was turning off the water to our home.

RC

[Steve]

Ron Cliburn wrote on 15 Dec 2007 in group alt.home.repair:

Congratulations on the repair. You're on your way to full-time employment as a handyman!

I'm glad the draining went well. It usually does, but some people have trouble getting the valve to close again because of lime buildup. It's even worse when the valve is plastic.

Yes, the cold water is introduced at the bottom of the tank by a "dip tube". Please check your emergency valve too. You should check it every year. Beware that it, also, can build up lime and not shut off, so be prepared for a trip to the hardware store.