Roughly a week ago, I started hearing sort of a 'pushback' or hammer noise coming from around the water heater. Noticed this everytime the dishwasher upstairs stopped the supply of hot water going into it. Thinking it was the dishwasher, I then tried the kitchen sink. When you abruptly shut off the water, and you are holding the hot supply line at the water tank, you can definitaly feel it, and hear it. You do not hear it at the sink/dishwasher area, but at the tank itself. If you slowly shut off the hot water at the sink, you do not get this type of action. I crawled under the house to see if the pipe was still connected (this is all in a farily tall crawlspace) and it appears to all be in fine shape. If I hold the line in the crawlspace while the water is abruptly stopped, I do not hear or feel it. I seem to only hear/feel it back at the hot water side of the tank. House was replumbed around 6 years ago with wirsbo/pex with crimp style fittings. Up to this point, everything had been hunky dory.
I did a little reading on here and did the whole turn off the water, open the hot/cold to drain the air/water out. I did this a couple of times and this didn't seem to make any difference. The cold water line doesn't seem to show this symptom, or at least it isn't apparent as much as the hot line.
I hope this is a decent explanation from a small brain like myself... Hope this helps. I was just hoping to cut in one of these arrestors on the 1/2" line before it enters the sink shutoff valve down in the crawlspace, or would a 3/4" one at the water tank make a difference?