I want to add a timer/programmer to the domestic hot water control on my ce ntral heating. The system uses Sunvic "MOMO" type valves so at each thermo stat there is a "common" and "open" and "close" terminal. I have managed t o get the central heating working on a simple programmer and double throw t ype thermostat but the hot water circuit is at present controlled by a sing le Honywell cylinder stat which annoyingly often switches on during the nig ht so I need to put a timer in this circuit to stop it coming on at night a nd gain more control over the water heating. The Honeywell cylinder stat has three wires going to it RED (common) YELLOW (1) and BLUE (2) . I thought initially I might be able to simply interrup t the supply with a single pole switch on/off timer in the RED common wire but thinking about it I guess it might cause havoc with the motorised valve s especially if it switched off half way though an open/close action. I hav e a double throw mechanical time switch which I thought might do the trick but I am uncertain of how to put it in the circuit. I only have access to the three core cable going to the cylinder stat. Can it be done?
- posted
10 years ago