need help wiring underfloor heating

[google]

Hi everyone
I need your advise how to wire up a heatmiser underfloor heating to an existing s plan system.

thanks

 

[ericmark]

The heatmiser unit is really a S plan, what is more to point is what you want to control, I note last zone can be switched as either UFH or Rad so it would seem it replaces the original wiring centre.

The circuit diagram seems reasonably straight forward, so what are you asking?

 

[google]

The heatmiser unit is really a S plan, what is more to point is what you want to control, I note last zone can be switched as either UFH or Rad so it would seem it replaces the original wiring centre. View attachment 162464
The circuit diagram seems reasonably straight forward, so what are you asking?

thanks for you replay ,im not sure where the orange and gray and brown wires terminate in the wiring center the client have Worcester s plan .

 

[SimonH2]

Two options come to mind ...
The first is to replace the existing wiring, and simply follow the diagram posted by Ericmark.
Alternatively, simply ignore HW Stat, HW Valve, Radiator Valve in that diagram. Then see at the top left there's a 3 terminal block labelled Boiler. Connect the C and NO terminals in parallel with the microswitches (grey and orange wires) in the existing S-Plan setup.

 

[ericmark]

The old Honeywell S plan has been around for a long time and can have as many motorised valves as you want, however the whole idea is the micro switch in the valve turns on the boiler, and the thermostat turns the valve on, with the under floor heating the valves don't have any micro switches, so you need the wiring centre which is a relay bank so there is a replacement for the micro switch so the N/O orange (boiler) just connects to the zone valve orange wires, and the C grey (boiler) connects to the zone valve grey wires. And of course the mains supply must come from same FCU as the boilers main supply.

What seems odd is you talk about a client so one assumes this is your job, and you can't read the wiring diagram? Which makes me think I have missed something, can't see why you would ask such a simple question if it's your job, so it seems it can't be as simple as it seems, so I am missing something. Maybe I have found wrong wiring diagram or it's not a standard S plan. There are some variations, where using a modulating boiler then the wall thermostat can connect direct to boiler onto the boilers bus, and the zone valve is only worked by the time clock for example.

Bosch Worcester has not signed up to OpenTherm so uses Wave which is their own thermostat which as far as I am aware will only work in one room, and you have to replace a lump in the boiler.

Years ago central heating was easy, you simply switched boiler off/on, but when the condensing modulating boiler arrived we started to control boiler by the temperature of return water rather than a simple off/on thermostat on the wall, however there is then nothing to switch off boiler completely as summer arrives, so we then got the return of the off/on wall thermostat normally fitted to coldest room, and the modulating wall thermostat, in some cases is gets quite complex where the thermostatic radiator valve (TRV) head tells a central hub how much heat it needs, and the hub calculates how much heat whole system needs and it in turn tells the boiler how many kW it needs to produce.

The whole idea seems to be, rooms only heated when required, so there is a move to fan assisted radiators to get the super fast warm up when required and much less water circulating around the system, the idea of under floor heating is the reverse of this trend, with much more water in the system. And I will freely admit not a clue how under floor heating works with modern modulating boiler, under floor heating I have fitted was really a heat sink to get rid of excess heat produced by solid fuel cooking stove side boiler.

So you may need to give us a lot more information for us to see where the problem lies.

 

[SimonH2]

What seems odd is you talk about a client so one assumes this is your job, and you can't read the wiring diagram? Which makes me think I have missed something ...

Struck me as a little odd as well. As you say, either replace the wiring centre and follow the "join the dots" diagram, or just treat the BOILER relay output as the same as a microsowitch in a zone valve. Perhaps he's one of these plumbers who only knows how to do the most basic stuff ("join the dots" following an old diagram he keeps in the toolbox) and can't cope with anything that's not on his crib sheet ?

 

[google]

The old Honeywell S plan has been around for a long time and can have as many motorised valves as you want, however the whole idea is the micro switch in the valve turns on the boiler, and the thermostat turns the valve on, with the under floor heating the valves don't have any micro switches, so you need the wiring centre which is a relay bank so there is a replacement for the micro switch so the N/O orange (boiler) just connects to the zone valve orange wires, and the C grey (boiler) connects to the zone valve grey wires. And of course the mains supply must come from same FCU as the boilers main supply.

 

[google]

Two options come to mind ...
The first is to replace the existing wiring, and simply follow the diagram posted by Ericmark.
Alternatively, simply ignore HW Stat, HW Valve, Radiator Valve in that diagram. Then see at the top left there's a 3 terminal block labelled Boiler. Connect the C and NO terminals in parallel with the microswitches (grey and orange wires) in the existing S-Plan setup.

thanks
I don't want to replace the existing wiring centre too much hassle i just have installed an underfloor heating and im adding new zone valve and not sure where the orange and brown and gray need to be terminated in the s plan wiring center.

cheers

 

[ericmark]

Sorry missed out neutral but really if you can't work it out you should not be doing the job, it is as you see colour to colour so really can't see the problem.

Grey and Orange go to all the micro switches to switch on boiler plus line neutral and earth so 5 core cable between the two systems.

 

[SimonH2]

I don't want to replace the existing wiring centre too much hassle i just have installed an underfloor heating and im adding new zone valve and not sure where the orange and brown and gray need to be terminated in the s plan wiring center.

In that case, you need to have your UFH WC control your extra zone valve. That means using the BOILER terminals to switch a live feed - connect C to L, connect the brown of the new zone valve to NO, and connect the blue of the zone valve to neutral. The UFH WC will then control the new zone valve, and you connect the orange and grey wires from that in parallel with the ones from the existing zone valves.
This is quite basic stuff.