Potterton netaheat 10 16 electronic

[Kenneth]

hi,just replaced the old ptt1 cylinder thermostat with a drayton hts3 terminal 1 to org . terminal 2 to grey and the common to terminal 3 inches junction box ,the problem I have now the HW shut off when the cylinder thermostat reaches the temperature that's good but I cannot turn it off through the timer the only way the HW can be turned off is by the main boiler thermostat

[John Rumm]

Hard to give any advice not knowing how the system is configured (what kind of valves etc). See if you can work out what type of zoning you have by looking at the following: