"RJG" wrote in
:

Hello,

I recently drained my gas water heater to flush out rust residue that
was starting to color my hot water. I am on a well and the previous
owner did not have a proper iron filter.

To do this I shut off the gas, opened the hot water tap in my upstairs
kitchen and drained the tank.
I filled and drained the tank a few times to get it clean.

Now the hot water looks much better, but the kitchen hot water faucet
will not run at full flow.
If slowly turn the faucet on and gradually increase water flow, the flow
reaches a certain level, I hear water hammer in the pipe, and flow
slows down considerably.

If I then shut off the tap and repeat the process, flow increases
normally, and then reaches a point where I hear the water hammer in the
pipe, and flow reduces. So the effect is repeatable.

So it seems that the hot water flow is being choked past a certain flow
rate.

Other hot water taps in the house work fine.

This tap is only a few months old and worked fine up until I drained the
water heater and hot water pipes in the house.

What could be causing this?

Some of the debris from the water heater likely made its way into the
supply for your problem faucet.

Try these steps. Stop when you have success.
1) Clean the faucet aerator.
2) Clean muck out of all the tiny openings inside the faucet.
3) Clean muck out of the supply line under the sink.
4) Flush the undersink cutoff valve into a bucket at full force.
5) Rig a hose to run cold water backward through the faucet into the water
heater. You may be able to do this with your back yard bibcock, but most
likely you'll have to use the neighbor's water.
6) Call a pro.

Let us know how things go.