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Hi All,
New to the forum and see that there has been a lot of help with this subject. I have a Honeywell Smartfit system that is on the blink and needs replacing. The issue is that unfortunately, the valves and cylinder sensors are proprietary; so I need to replace them to fit a Nest or anything else.
I have an HRM Wallstar Oil Boiler (On Ground Floor), Hot Water Cylinder and CH Pump configured in an S-Plan arrangement at the moment (In First Floor Airing Cupboard). I plan on replacing the 2no valves with new 2-port valves with traditional 5 wire cabling and the cylinder thermostat with a new one with a Common, 1 (Call for Heat) and 2 (Satisfied) terminal.
I have attached some images of the Valve/CH Pump arrangement and the existing wiring within the Honeywell Smartfit Base Unit:
I am fairly happy with everything in the Nest Manual. I have attached a sketch of the schematic how I believe it should be installed to:
But have a couple of queries I wonder if anybody can help with:
Regards,
Oliver
New to the forum and see that there has been a lot of help with this subject. I have a Honeywell Smartfit system that is on the blink and needs replacing. The issue is that unfortunately, the valves and cylinder sensors are proprietary; so I need to replace them to fit a Nest or anything else.
I have an HRM Wallstar Oil Boiler (On Ground Floor), Hot Water Cylinder and CH Pump configured in an S-Plan arrangement at the moment (In First Floor Airing Cupboard). I plan on replacing the 2no valves with new 2-port valves with traditional 5 wire cabling and the cylinder thermostat with a new one with a Common, 1 (Call for Heat) and 2 (Satisfied) terminal.
I have attached some images of the Valve/CH Pump arrangement and the existing wiring within the Honeywell Smartfit Base Unit:
I am fairly happy with everything in the Nest Manual. I have attached a sketch of the schematic how I believe it should be installed to:
But have a couple of queries I wonder if anybody can help with:
- I assume that the CH pump Earth and neutral are fitted into the general earth & neutral connector.
- I am not sure whether the pump should be installed in the mains live or the Boiler/CH or HW Valve Lives. I assume that it should only be triggered when a signal to the actuators is given or is it always on and activates when water is drawn across it?
- (Helpfully!) My boiler has a Switched Live (Manual says "From The Timeclock" in brackets) and a Permanent Live (Manual says "Must Bypass The Timeclock" in brackets). I am not sure how these connect. My assumption would be that the Switched Live is wired into the Orange cables from the CH & HW Valves (Into Connection Terminal #10) and the Permanent Live is connected to the mains live (Into Connection Terminal #1).
- The Cylinder Thermostat has a Common and 1 (Call For Heat) as the Nest Schematic; but also another terminal labelled 2 (Satisfied). I assume that this is another feedback which other heating systems may need and I can leave it unconnected as the S-Plan Nest arrangement doesn't need it.
- Finally, I assume that if I turn off the boiler and bung the cold cistern in the attic, I can open the valves manually and drain the First Floor heating system only to drain the water around the two valves as it will take all the water out of the radiators and the coil in the hot water tank?
Regards,
Oliver
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