Water Hammer

Can anyone here tell me the thread that discusses how
to drain your pipes to evacuate the air that maybe causing
water hammer???

Is it as simple as

1. Turn off main water shut off
2. Flush water from all lines> I assume
you open the all faucets in all bathrooms
ect??
3. Turn water on?

Ski

Any air chamber open to the water supply will quickly have the air absorbed and stop functioning. The only way to resolve this long-term is to use a proper engineered hammer arrester. These either have a piston or bladder that separates the air and water.

Just like a soda straw with your finger over the end, you may not get all of the water out of an air chamber...So, good luck.

skidoddle said:

Can anyone here tell me the thread that discusses how
to drain your pipes to evacuate the air that maybe causing
water hammer???

Is it as simple as

1. Turn off main water shut off
2. Flush water from all lines> I assume
you open the all faucets in all bathrooms
ect??
3. Turn water on?

Ski

Click to expand...

These are the steps you take to remove all the air in the system. With all faucets open there is really no way you can trap air in your system. Unless ofcourse you have an old house and someone has installed hand made shock arresstors.

Flush your toilets too.

If you do all this and you're still getting water hammer then there is something else going on and it's not air. Your PRV may have failed and now suddenly you have much more pressure and velocity in your pipes. Maybe some strapping came loose.... etc.

air chambers

As a practical matter, it is almost impossible to get all the water out of the system, especially in "drops" so that the air can get TO the air chambers. And once it does get to them, there is also the problem of the water draining from the air chamber which probably will not happen since you cannot "open" the top of it to let the water drain out.

Before I found out about hammer arrestors, I used 3/4" x 16" pipe with caps.
Those would water log in a few months, but would drain out, because of the larger size.

The other day, I replaced and outdoor hose bib in the garage.
There was a 1/2" pipe from the 1" before the tee for the hose bib.
I pulled it's cap off hoping to drain below the solder joint for the hose bib.
The 1" x 1/2" had plugged and I had to use a screwdriver to knock out the sediment.
Unused stub outs can fill with gunk.

air chambers

When I used to install them, I would use a 3/4x1/2x1/2 tee with a 3/4 riser. The larger area gave a better chance that air could get into them to let the water escape, but it was always a toss up whether it would actually happen.