The Caretakers' Forum

PAUL.C wrote: ↑31st Mar 2023 at 10:40amwhy

If its being stored at 60 degrees for example, but coming out at the end of the run at 45, then there's possibly an issue somewhere down the line, which would need keeping an eye on/investigating.

On the flip side, if your cold tank is storing at 15, but comes out of the tap in the low 20's, is it because there's a hot pipe that runs parallel with it which is heating the water in the pipe up, or is it just a really hot day.

Should take storage temps, but also needs to be the running water temperature, which can tie in with your water flushing anyway.

PAUL.C wrote: ↑31st Mar 2023 at 10:40amwhy

For many, many reasons of which some good examples have already been given.

PAUL.C wrote: ↑31st Mar 2023 at 10:40amwhy

because the system as a whole needs to be safe. Just checking a cold water storage tank or hot water cylinder doesn't tell the story of what's going on by the time it comes out at the taps.

Case in point at a previous site - cold water taps in classrooms with pipes running parallel to and ABOVE heating pipes. The taps were lovely to wash your hands with but not safe from legionella risk. The solution was to lag both cold water and heating pipes to reduce the risk of heat gain into the cold water system.

Taz wrote: ↑31st Mar 2023 at 10:58am If its being stored at 60 degrees for example, but coming out at the end of the run at 45, then there's possibly an issue somewhere down the line, which would need keeping an eye on/investigating.

On the flip side, if your cold tank is storing at 15, but comes out of the tap in the low 20's, is it because there's a hot pipe that runs parallel with it which is heating the water in the pipe up, or is it just a really hot day.

Should take storage temps, but also needs to be the running water temperature, which can tie in with your water flushing anyway.

Most hot taps have blending valves fitted so yes stored at 60 and the outlet 40.

PAUL.C wrote: ↑3rd Apr 2023 at 1:35pm Most hot taps have blending valves fitted so yes stored at 60 and the outlet 40.

In which case you would measure the temperature of the hot water pipe just before the blending valve. Our sentinel points all don't have blending valves (kitchens or cleaning cupboards) so we can measure the water at the outlet.

No one's considered high CWS temps being caused by TMVs? If you know that the HWS system runs at a higher pressure than the CWS (pumped hot?) and just one TMV cold check valve sticks open, the result is hot water backing up into the cold resulting in cold water at a higher abnormal temperature. Left over a wekend or holiday, the whole CWS system can come up in temperature very quickly.

Just a thought .