The Central Heating decided to stop working today - had a bit of a hiccup a couple of weeks ago but now gone solid. It's a standard open vented system - Boiler, Pump, 3 Port Valve, Cylinder, Radiators, Programmer, Cylinder Stat, and Room Stat. Boiler - Glo-Worm 24Hxi Programmer - Drayton Lifestyle LP522 Room Stat - Drayton Lifestye +2 The problem is that the Central Heating side stopped working - no heat rushing round the radiators. The hot water side is working fine. I switched off the power and checked that the 3 port valve felt ok by moving the manual lever, and that seemed ok. I then switched the power back on, made sure the room stat was calling for heat, popped the cover off the electrics in the airing cupboard and checked for a signal from the room stat. No signal. Power going to the Room Stat as expected. So - I changed the batteries in the room stat. I have had a problem before where the batteries had been good enough to power the LCD but not switch the solenoid. However that didn't work. From this I deduced that I needed a new Room Stat. So - I bought a Digistat +3. Popped the cover off the +2 and replaced with the +3 - still no joy. So replaced the back plate as well. Still the same! I pulled the front off and double checked there was mains on pin 1. I can't have two dead room stats, can I? Thoughts, Roy
have you got voltage on the white of the valve when CH is on programmer and room thermostat is turned up?
OK - This is really, really embarrassing... I thought I would just double check all voltages before replying to you. And for the first time today I have seen 240V on the white pin. How can this be! I have a feeling it's because I have been using a pipe to provide me with earth - because all the earth wires were taped up. Anyway - I attached is a diagram of what's in my airing cupboard box, and what's on each terminal. I guess, because there is 50V on pin 5 coming out of the 3 Port Valve - that looks like the culprit - yes? I'm also bemused as to why I have six cable coming into my box! Many thanks for your help. Roy
"I guess, because there is 50V on pin 5 coming out of the 3 Port Valve - that looks like the culprit - yes?" Opps - No - that's not right... Hmmm...
I copied this text from somewhere, maybe off here a good few years ago and kept it as a guide. If you have 240v on the white CH demand wire, and 240v on the grey HW OFF wire, this is the only condition where the orange wire WILL become live to 240v. If the white CH demand wire is 0v, and the grey HW OFF wire is 0v, the orange will be 0v and the valve 'relaxes' to it's spring return position of HW only. The cyl stat will then provide power to the boiler to run directly (same terminal as the orange) assuming the timer is calling. If the white CH demand wire is 0v, and the grey HW OFF wire is 240v, the orange will be 0v and the valve will stay in what ever position it previous was, and if this last position was central heating only, this is when you will see 100v on the orange. If the white CH demand is 240v, and the grey HW OFF is 0v, the valve will be in the mod position, the orange will be at 0v (but boiler will fire due to the cyl stat firing the boiler (same terminal as the orange). For the orange to become live to fire the boiler when hot water is OFF or SATISFIED, you MUST have a HW OFF cable from the time clock and a HW Satisfied from CYL stat. If there is not 240v from either of these sources, the valve will not provide power on the orange to fire the boiler in the CH only state.
OK - so - in my situation - the system is set so that CH is on at the programmer and hot water is off. I have 240V on both White and Grey going to the 3 port Valve - pin 8 and 10 in my diagram. However, the orange (red in my diagram) is at 50v. It connects to the cylinder stat and also goes off down cable 3, I assume to the programmer? I imagine it comes back up cable 2 - on the blue wire - thence to the pump? Is that right? So why isn't it at 240V - Is that the problem - it is a problem with the 3 port valve electronics? Many thanks for your help, Roy
Hot water works as valve is relaxed state is HW only. The motor motors to mid way (HW AND CH) and then past this to CH only, shutting the HW port. If motor fails to move, valve stays in HW only position.
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