is this water hammer?

(edit: 48 hours later - problem seems to be solved - thanks)

Hi all, hoping to solve a lil problem.

My kitchen sink has a single handle faucet that blends from cold to hot as desired. The problem described may have to with the method of hooking up the hot water..?..

When trying to use hot water in the sink, it will flow a bit. As it starts to become warm, it'll bang a time or two, then stop completely. When I move the faucet handle to bleed in some cold water, it will flow and eventually warm somewhat with the limited hot that is flowing through. Trying to go back to hotter, or hot only, will again stop the flow completely with something of a bang.

Plus, running the dishwasher is basically not possible. It will cause pretty aggressive banging though its' running water cycles.

The hot line is connected as shown. There is the copper to the valve, and the two lines from the valve, to the sink and the dishwasher.

The dishwasher has a high loop waste into the sink drain before the trap. fwiw, there is no evidence of water backing into the dishwasher. It's clean. I'll likely add an air gap but that would not play into the other issue would it? And what does?

Thanks in advance for any ideas. I'm plenty ignorant here.



The Washer, and everything in the full bath work as they should. Between them, that represents connections both before and after the kitchen stuff.

sounds like a problem with the faucet cartridge. It is not water hammer

Since it affects both the sink faucet AND the dishwasher I'm going to say that it is either the stop valve or another valve in the hot water branch serving the sink and dishwasher. Most likely a loose washer in the stop valve.

Furd said:

Since it affects both the sink faucet AND the dishwasher I'm going to say that it is either the stop valve or another valve in the hot water branch serving the sink and dishwasher. Most likely a loose washer in the stop valve.

Click to expand...

Showing my ignorance... The stop valve (or one candidate anyway) would be the hot valve in the pic with 2 attachments? I'll check the guts.

Looks like the faucet issue is resolved. I turned off the house water,
(all 'valve' references refer to the hot and cold under the sink, shown in the original picture in post #1.)
pulled the hot water valve core,
all looked well, washer looks great (flat washer, not beveled),
hole in the pipe is clear,
put valve core back in and tightened it up.
turned house water on,
left hot closed and ran cold only - ok
turned cold off and ran hot only - ok
turned cold back on (both on now) and ran forever,
hot runs full if called on, no stoppee, just as it should.

YAY. Theory - The valve was FAR from fully open when I started looking. Could have slowly tightened,(?) to allow the washer in there to start chattering and be bad! It IS a loose fit washer so I could see that going on. Both valves are not quite fully open now (opened full and backed off slightly).

Running the dishwasher now to prove full fix...
later: Yep, it ran fine as well.

Ahhh, life is good,

Thanks for the pointer. This was kind of a laying on of hands thing. Works now and I'm lovin' it.

A Plummer once told me that the water hammer was caused by air in the water lines. To cure this he shut off the water at the main and drained all the line by opening all the faucets. After water quit running he turned the water back on leaving the all the faucets open after about a half hour he started turning the faucets off one at a time. When he was finished there was no more hammering sounds. When I say all the facuets I mean all outside and inside.