Which pocket for the temperature probes in the Unvented cylinder (UVC)

[MikeSharp01]

Almost complete on the HP install all flushed through, pressure tested everywhere and filled for testing (still need the inhibitor)  Powerup tomorrow, would have been yesterday but weather stopped us because you have to take the lid off the HP to make the final electrical connections if you want a BMS connection.

 

Anyway the final challenge is to fit the temperature probes into one or both of the pockets in the UVC. There are two pockets one at about 50% height and one at 75% height and there are two probes. One (A) looks after the immersion heater and the other  (B) looks after the Heat Pump - sends Domestic Hot Water (DHW) data direct to the HP presumably for the HP to know it has got the water to the required set point. The tank is quite dumpy and 200l so I assume it makes no difference as the tank probably does not stratify so well that it matters. Have I go that right? To help me out I have used the top pocket for both so if it does stratify I am working on the hottest water and I can read the temperature from the BMS and its reading the same temp as the immersion limits.

[John Carroll]

If you are talking about a Immersion then presumably its a Electrical Immersion, if so, the UVC will have somewhere to install this, these immersions have their own integral stats and measure the water temperature where ever they are installed, THe 50%& %75% probes should determine what vol of hot water  is used before the HP or boiler is called on to start reheating, HPs might tend to have the probe at 50%, if measuring from the bottom up then the HP might use the 75% pocket.

Edited 4 hours ago by John Carroll

[ProDave]

The tank WILL stratify.  Not so much when it is being heated, but as you draw hot water it exits at the top and is replaced by cold water entering at the bottom.  Those don't mix much so the hot / cold transition just moves up the tank.

 

So you want the heat pump probe, the one the heat pump used to measure temperature in the lowest pocket available, so it detects the cold water as soon as possible and starts re heating.

 

I initially tried mine in a higher pocket, and the tank did not re start heating until half the hot water had been consumed.

 

The immersion heater one?  Are you talking about the safety thermostat part of the cylinders safety system?  I have that in the higher pocket.  this is the one that is supposed to shut down the heating demand and close the motorised valve to protect from a runaway out of control heat source.

[SimonD]

3 hours ago, MikeSharp01 said:

UVC

 

What UVC have you got? I'd usually expect the pocket for the dhw thermostat to be about 1/3 way up. Can we have photos?