Fitting water hammer arrester.

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the op isnt complanin about the flow.

agree modern arresors are way to go. bad experience saysthat stubs of pipe can sometimes fill up in 12 months or so.then youve got to drain down an start again but in a tricky installation refillin could introduce possible air locks.

site an fixin a expansion vessel probly isnt for diy an the diaphragm can wear pretty quick in some conditions.
as far as i now they are for temp expansion.
I was reminded about this post I made a few years ago. The device is still working ( but not on my machine )
The pipe to the washing machine does not need to have a tap on it, just the hose to the appliance. The tap shown can be the appliance isolator. To reinstate the air cushion, just turn off the one isolator that is shown, and turn on the washing machine. The expansion pipe is Emptied. Then turn on the isolator to complete the wash cycle and reinsate the air cushion. The isolator has to be in a convenient location, like in an adjacent cupboard. A 1/4 turn stoptap would be ideal for user use.
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i guess the isolator you ref to is the w/m tap.
the diy arrestor will be on the w/m inlet male with the w/mhose attached to the arrestor?
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Use only one tap, as shown. The outlet pipe to the hose has no tap. Read again what I wrote. A DIY job to reinstate the air cushion. The device needs to be above the appliance to drain out.
i understod your post was offpage about a diy arrestor at a w/ problem with thatbut your description an terms confused me.

whoa! youve changed your post.
on my screen ther was no pic of a tap or instruction to expand the pic in bernardgreens post?now i look again an a iso appears when i click the expansion thing.

anyway ive learned somethin new an interestin.
well bernard was correct about needing to loosen it. Perhaps the word "drain" is misleading, because in reality you're replacing the water with air. If you just turn the washer on, no air can get back in so there won't be any draining going on. Same as when you break into a pipe with the stop tap off. nothing much will drain until you open a tap higher up in the building to let the air in.

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