The house was built 1994. The pipes are plastic
There likely is some sediment or corrosion , this could be just in the hot water shut off valve under the sink. Or a supply line to the faucet. The Branch line could be Clogged. The most likely thing with this is going to be a loose or broken washer in the under sink valve.
The hot water shut offf valve under the sink was tested by rerouting to the dishwasher cutoff valve with the same result. All washers were replaced today when the faucet was replaced and the supply line from the cutoff to the new faucet was replaced today as well.
Either the branch line supplying water to the kitchen is Clogged, or the new faucet is bad. To test this the flow should be checked first on the cold water flex line running to a bucket, time How long it takes to fill, then test the hot water flex line. Of it fill the bucket very slowly with a new supply line, and the dishwasher supply valve is also slow, then the branch line will need either replaced or attempted back flushing.
We checked the things that you suggested and you were right, the cutoff valve is broken. The plumber told us that he checked it today but it seems that perhaps he didn't. Now the question is whether to trust them to come back and finish the job that he started or find someone we can trust. And I have a new faucet that I obviously didn't need. :(
Thanks again for your help.
I think, if you believe the plumber is from a reputable company, then you should give him a chance to redeem himself. Have him replace the hot water cutoff valve, and show him how this resolved the problem, and ask if he can give you a discount on the faucet. Of course there should be no extra charge to install the hot water cut off valve. If he refuses to comply, or tries charging you more, your best recourse is a scathing review online. Sometimes this will help him decide that it is best to admit his mistake and make it right.
Sorry about your inconvenience. Hopefully you will be able to come to a fair resolution.
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