We had our kitchen tap changed yesterday afternoon (the new faucet has two taps and one spout and suitable for ALL PRESSURE).

And since then the water has been running down the overflow pipe on the side of hot water cylinder through the pressure relief valve. The hot water is not hot at all, probably 30 degree or even less, only a little warmer than cold tap water.

The hot water cylinder is an electric low pressure one. We have been assured by the tap supplier that the new tap is not the cause, since it is suitable for all pressure.

We tried to turn on and off the pressure reducing valve in the basement under the cylinder, but the water is still running. The only time that it stopped is when the house water was shut off.

Could anyone help us to figure out what the cause is? Because this happened after the new tap, so my first guess is the tap. The plumber who installed the new tap disagree, but not giving me much answer about the overflow. Could it be the pressure relief valve or pressure reducing valve under the cylinder, or something else may be causing this?

Thank you in advance.

Linkback: https://www.plumbers.nz/q-and-a-hot-water-cylinders/44/hot-water-cylinder-overflow-continuously-and-water-is-not-hot-at-all/334/

Hi ,I have to disagree if it were your faucet it would only happen if you were running both hot and cold at the same time and to run the cylinder cold you would have to have both taps running for a long time
 
.My guess would be that when your plumber installed the taps. He shut of the toby and the hot water cylinder to prevent hot water flowing back through the cold line to the sink .

Now either way be it from dislodging some grit in the toby (holding the Ajax valve washer open ) or tuning valves in the hot water cupboard bumping an old relief valve  .

Either way its time to get both valves inspected serviced and or replaced .
Cheers Ali

wouldn't you just check the press red. valve washer first?