Terminal connections on cylinder thermostat .
The Common terminal on cylinder thermostat should be connected with the hot water on terminal from programmer. . Normally Closed/Break on rise (or call/on need heat) terminal on cylinder thermostat should be connected with the orange on 3 port valve and switch live to boiler (pump also could be connected here if boiler doesn’t have pump over run). . Normally Open/Make on rise (or satisfied/off no heat) terminal on cylinder thermostat should be connected with the grey on 3 port valve and hot water off from programmer.
Positioning of cylinder thermostat
When used with factory insulated hot water cylinders, sufficient insulation must be removed (if it isn’t already) to allow the base of the cylinder thermostat to be in contact with the cylinder wall. The cylinder thermostat should be mounted approx one third of the way up from the bottom of the cylinder and on the opposite side to the heating coil. Most cylinder thermostats are supplied complete with a metal spring band, which assures a good clamping.
Heating: Y-plan cylinder thermostat installation and replacement guide 2016-08-20
Guidance notes on Y-plan cylinder thermostat installation and replacement