I am installing cpvc supply in a detached garage to make into an apt. do I need to make provision for anti-hammer as I have seen in copper installations? Pressure is around 80 psi, with 3/4" service to garage, apt will have : toilet, bath lav, shower, kitchen sink,electric water heater, possibly washing machine.

You need an air chamber, this prevents water hammer. Why is your pressure so high, norm is 40-50 psi inresidential apps.

Not sure if the pressure reading is accurate, the pressure gauge and test fitting were left over from a remodel job long ago.The city w.p. had been intentionally lowered by the utility to help with the drought and ensuing water use restrictions. I'm not sure if they raised it or it is an erroneous reading. Assuming the pressure is within an acceptable range, does each fixture require an air chamber, are they cpvc or they cu/ with cpvc connection, and are they available ready made?

561 ratpack...

With the fixtures you mentioned I would install water hammer arrestors at the washing machine... both hot and cold lines get one each. The washing machine has fast acting solonoid valve that can cause water hammer when turns on or off so it is always a good idea to install them here... ;)

Water hammer arrestors (see picture) are available with a threaded connection and can be joined to a cpvc or copper female adapter (see picture below).

Otherwise, hang pipes correctly and should not need to install them anywhere else.

I would also have you confirm your pressure by purchasing a hose bib pressure gauge (see 2nd picture... available at home depot for $10.00) and taking a pressure reading by connecting it to your outside faucet. If the pressure is anywhere near 80PSI then I would have you install a pressure reducing valve (see last picture) and reduce the pressure to about 50PSI or so... your pipes, especially if CPVC, and all the valves and faucets in the house will last a lot longer and have fewer repair issues over time if you do. I promise!

Let us know if have any more questions...

MARK

does each fixture require an air chamber, are they cpvc or they cu/ with cpvc connection, and are they available ready made? To add a little to Marks answer. In addition to the washer our code mandates that we install air chambers on the hot and cold stub-outs of all lavatories and the kitchen sink. These air chambers can be manufactured, as in Marks image, or you can make them yourself out of 12" of 1/2" or 3/4" PVC on the cold side or CPVC on the hot side with hard caps. Your choice. Good luck, Tom

Funny how codes differ from state to state huh..?

In my area we are not required to install air hammer arrestors on anything... not even on washing machines.

Many old school plumbers and even some of the new plumbers being trained by old timers will install air chambers by making them from 1/2" copper or 3/4" copper x 12" and capping them (as mentioned by Tom)... but I don't do it myself (even though I was trained to install them by an old marine shipfitter that was in the water for 3 days at Iwo Jima). Instead I hang my pipes properly and add plastic inserts wherever I penetrate wood in any way and I allow for expansion/contraction of pipes on longer runs. Now, I am not suggesting that people that install hammer arrestors are not hanging their pipes properly... ok? But, I am suggesting that I have never had any issues (residential or commercial) except on washing machines... especially the newer ones with the faster closing solonoid valves... so now I install water hammer arrestors on all washing machine water lines.

Anyway... did not know Florida required them, Tom. Interesting for sure! They sure can't hurt anything... ;)

Thanks all...

MARK