Electromechanical Y Plan System Explained Simply with a Hive Thermostat скачать в хорошем качестве

Electromechanical Y Plan System Explained Simply with a Hive Thermostat

1. What is a Y Plan system A Y Plan system uses: • One 3 port mid position valve • One room thermostat • One cylinder thermostat • A programmer or Hive receiver • Boiler • Pump Instead of two separate 2 port valves like S Plan, Y Plan uses one valve that does three jobs. That is the big difference. 2. Why it is called Y Plan The pipework forms a Y shape: • One flow from boiler • It splits to heating • It splits to hot water cylinder One valve controls where the water goes. 3. Inside the 3 port valve Inside you have: • Small motor • Gears • Spring return • Two microswitches • End switch This is electromechanical. Electricity moves the valve. The valve position controls water direction. 4. The three positions of the valve This is the most important part. The 3 port valve has three working positions: Hot Water Only Heating Only Mid Position which means both Remember this clearly: White wire controls heating demand Grey wire controls hot water satisfied Orange wire fires boiler 5. Scenario 1: Hot Water Only Hive hot water ON Cylinder stat calling No call from room stat Valve stays at rest position Water goes to cylinder only Boiler fires In Y Plan, rest position is hot water. 6. Scenario 2: Heating Only Hive heating ON Room stat calling Cylinder already satisfied Grey becomes live Valve drives fully across End switch closes Boiler fires Now water goes to radiators only. 7. Scenario 3: Heating and Hot Water Together Both stats calling Valve moves to mid position Internal switches allow boiler to fire Water splits between both circuits This mid position is why Y Plan is more complex than S Plan. 8. Where Hive fits in Hive replaces the old programmer. You will have on the receiver: • Permanent live • Neutral • Earth • Heating ON • Hot water ON Hive sends the signals. The cylinder stat and room stat still control final demand logic. Hive does not change how the valve works. It only controls when the system is allowed to operate. Traditional wiring. Modern interface. 9. Why Y Plan can be tricky Because: • One valve does everything • Two microswitches inside • Mid position logic can fail • Backfeeds are common if wired incorrectly When it goes wrong, engineers get confused. But if you remember: White = heating demand Grey = satisfied signal Orange = boiler fire It becomes logical. 10. Common faults you will see onsite • Valve stuck mid position • No hot water but heating works • Boiler running constantly • Grey wire permanent live issue • End switch failure • Cylinder stat miswired Most problems are electrical logic, not hydraulic. Simple Mental Picture Think of Y Plan like a traffic junction: One road from boiler. Traffic lights decide: Left to cylinder Right to radiators Both directions The valve is the traffic light.