On Mar 19, 2:23*am, "Gary" wrote:
"fftt" wrote in message

...
On Mar 18, 8:36 pm, "Gary" wrote:

I installed 4 grohe thermostatic valves today with volume control valves.
3 showers and one tub. I ran water to them and found that two of them
would hammer when turning off the volume valve. Because I used pex I can
see that there is air in the lines. I have let them run for about 20
minutes but the air doesn't want to come out. I can't see it when the
water is flowing, but when I turn the water off I get the hammer noise and
then the air appears and it looks like it comes out of the valve into the
pex.

Will this air come out of the water line with use? Or is there something I
should do? I would like to make sure that my pipes won't be hammering once
I have my drywall installed.

Thx

The air should clear on its own...if you;re getting hammer, pressure
is too high, valve shutoff too quick, need to add arrestors

cheers
Bob

Thanks Bob. *I just put a pressure gauge on it and got 85psi. *Should I be
looking for a regulator?

Gary-


For residential supply, 85 psi is rather high. The arrestor folks
(jrsmith mfg) suggest keeping pressure under 65 psi.

When I repiped I installed arrestors in various locations and a Watts
pressure reducing regulator. I went from 75 psi down to 65 psi. I
miss the "firehose" behavior of my garden hoses but I don't have any
hammer.

If oyu really want to read about arrestor behavior & placement

http://www.jrsmith.com/products/water/pm/pm1054.pdf

I cheaped out & didnt put on on my upstairs toilet....still had
hammer, but attic access allowed me to install one in a few minutes.

Even with PEX (which is more flexible than copper or steel) I would
put arrestors in kitchen (d/w & ice maker), laundry for sure and all
toilets. My downstairs toilet only has about a 15' run from the
manifold...no arrestor / no hammer.

cheers
Bob