x-posting with plumbing forum, still need help please!

Ever since our kitchen renovation, the cold tap on our two kitchen sinks both pour out hot water for the first 8-9 minutes. We have to waste a ton of hot water before the water finally becomes cold. Sounds silly, but it's so hot that you can't even wash your hands without running the water first. Then, if we wait twenty minutes or so, the cold tap again becomes hot and I have to run it another few minutes to get cold. If you run the cold tap continuously, the cold stream doesn't stay cold, either--it will change to tepid, then warm, the cold again after a few minutes. The hot water tap works fine--cold for a few seconds, then hot, as expected. This happens only in the kitchen. The bathrooms are fine--and they are approximately the same distance from the water heater as the kitchen.

We had a recirculator at our hot water heater, which I turned off and unplugged, thinking that was the problem. I really thought it must be related to the recirculator because the problem always seems worse at certain predictable times (afternoon). But there was no change. We also adjusted the hot/cold balance under the sink. But the problem continues. Our gas bill is quite high and I'm sure all this wasted hot water is one reason. I'm worried that our sinks might not have been plumbed correctly during the renovation.

Had our GC back out to look, but he'd never seen anything like this before. He called the plumber, who's coming out next week--but he didn't have any ideas either, and the walls are closed up already.

Any thoughts what could be causing the problem?