[tidelaw343]

We recently had our bathroom renovated in our 55-year-old home, a process that included new sheetrock, tile, a new tub, and a new shower fixture. The original plumbing that was run at the time the house was built included a three valve tub faucet. We replaced it with a single valve system, and the new plumbing included a mix of hard lines and flexible piping (I assume it's some sort of flexible PVC, it's blue). I know nothing about plumbing outside of mounting a sink or toilet. Hot water for the house is produced from an oil furnace/boiler that is also responsible for our baseboard heat.

For the first month of using the "new" bathroom, everything was fine. Showers were hot, there were no leaks, everything worked great. In the past week, the weather dropped here from highs in the 80s/90s to highs in the 60s. For the past three days, our showers have been lukewarm, and trying to get more hot water by turning the knob produces more hot water, but also a knocking in the pipes behind the wall. Presumably, this increased demand from the hot water line is causing the knocks.

We had the furnace guy out today, and our boiler is fine. He suggested tweaking the anti-scald disk in the valve, which I did tonight. The change was mild and we're still not getting the temperature we want/used to get, plus the knocking is still there when you crank the hot water.

Our contractor sourced our plumber, so I dread trying to find this guy or deal with our contractor again, but when I do (see how good this warranty really is), what do I need to make sure they check to remedy this problem? I don't want to run into one of those "turn a screw, scratch their head, that's all I know to do" things, and I certainly don't want a back and forth between them and the furnace guy.

[ballengerb1]

Do not tweek anything. How long ago was the remodel? Your installer/plumber should come out an take a look. I think some debris came loose in your hot line and is caught in the intake. Knocking can also be a loose washer vibrating, it will reduce the flow considerably. Call your contractor and tell him you want him to fix it. If the remodeler won't help come back and we will try to walk you through the steps

[hkstroud]

Hot water for the house is produced from an oil furnace/boiler

the weather dropped here from highs in the 80s/90s to highs in the 60s.

trying to get more hot water by turning the knob produces more hot water, but also a knocking in the pipes

All those things make me think you have a problem with the domestic hot water mixing valve. Knocking should be loudest and pipe vibration should be greatest at the valve on the boiler.