Heating Controls Question.

[padstar]

Please can someone help me out with this one.

I have a boiler, cylinder, 3nr 2 port valves a thermostat/programmer and UFH downstairs'.

I understand the basics of the S- Plan heating controls as below;

Boiler, 2 port valves and thermostat/programmer (nest) are all connected to the wiring system.

Stat/programmer calls for hot water or heating to rads, this triggers the boiler to start heating and the associated valve to open to allow hot water to the cylinder or to the rads.

UFH has a separate control centre, which I understand works as below;

Stat calls for heat, control centre triggers the boiler and UFH valve to send hot water to the manifold to heat the zone calling for it.

Assuming the above is correct what I cant understand is do these operate as 2 separate control systems, each with a link back to the boiler with 2 valves on the heating (Hot water and rads) and 1 valve on the UFH, or are they somehow linked?

 

[CBW]

They’re usually just switches, so all wiring will be linked to boiler and or pump live, just operated by different switches.

 

[padstar]

So the two wont be connected to each other?

 

[CBW]

One can’t control the other, if that’s what you’re asking?

 

[padstar]

Ok so i will have 2 control systems

1) An S-Plan control center connected to the boiler and thermostat/programmer and 2 valves which calls for heat and controls the valves for the hot water and the upstairs radiators

2) UFH control center which is connected to the boiler and 1 valve. This calls for heat to the UFH manifold.

If this is correct i think i understand. For some reason i thought they all went through the same control box

 

[CBW]

For some reason i thought they all went through the same control box

Likely to go through the same wiring center, but if everything is heated via the boiler, then they‘ll be connected somewhere.

 

[milgo123]

Is this not essentially an S-plan Plus from a wiring perspective?! So long as you have enough (spare) connector blocks in the main wiring centre then additional UFH zone valve and pump could make their connection there?!

I'm not a plumber, just trying to think logically.

 

[padstar]

That is what I originally thought but got very co fused as to how the UFH controller links to the main wiring center

 

[MeldrewsMate]

So the two wont be connected to each other?

Think of each two-port valve as a relay. When the valve is 'energised' by its individual control it sends an isolated electrical signal to the boiler. The 'coil' is energised by the stat, the grey wire is permanently live, the orange wire is the switched output when that valve is open.
In logic terms each is an OR gate, just one or several or all of these operated will call for heat from the boiler.

 

[dilalio]

In easy peasy terms...

An S Plan + system will have at least 3 zones, controlled by 3 channels.

Each channel (whether in 1, 2 or 3 programmer units) will have its own timeclock.

Each timeclock will energise a switched live wire during scheduled demand periods.

Each switched live cable will pass through a thermostat (room or cylinder).

If the actual temp is below the setpoint temp of the thermostat(s), it/they will "make" the circuit and continue the path of the energised switch wire on to a 2 port MV, associated with that thermostat/channel/zone.

At the relevant 2 port, the incoming energised switch wire (from the thermostat [brown wire]) powers a synchron motor to open the valve allowing water to flow freely though it.
The motor also has an armature which, at the end of its travel, presses a microswitch.

The microswitch "makes" a circuit between the grey wire and orange wire of the motorised valve. The grey wire is a permanent live (from the wiring Centre) and the microswitch (when depressed by the armature) sends power down the orange wire, which fires the boiler and runs the pump.

Think of these orange wires as "fire wires" they are connected together and to the boiler (and pump) and 1, 2, 3 (or more) of them can bring on the boiler.

So, in essence, it's the 2 port valves that actually fire the boiler (and pump) by connecting the permanent grey wire to the orange when the microswitch is depressed.
The microswitch is only depressed when the valve has opened (thus allowing water to flow freely through it) and the valve only opens when the live signal has made it all the way from a timeclock, through a thermostat, to the valve motor, via the brown wire of the zone valve.

Simples!

 

[milgo123]

@dilalio Thanks for a very informative post, delivered as simply as could be. 1 question...an UFH manifold, complete with pump...when the UFH zone valve "fires" calling for heat, obviously the pump on the manifold starts to run to circulate water around the loops, but would the "main" pump as connected to a regular S-plan also need to be started as it is likely to be downstream of the manifold pump?

 

[dilalio]

@dilalio Thanks for a very informative post, delivered as simply as could be. 1 question...an UFH manifold, complete with pump...when the UFH zone valve "fires" calling for heat, obviously the pump on the manifold starts to run to circulate water around the loops, but would the "main" pump as connected to a regular S-plan also need to be started as it is likely to be downstream of the manifold pump?

Normally yes.
The system pump would circulate the water to the manifold via flow and return.
The manifold pump then circulates the water around the loops.
There is potential for pump clash, however, the blending valve creates a form of hydraulic separation between the UFH pump and system pump and both should ErP (depending on age) and should modulate.
There are new system designs that are different from this but traditionally, is as I describe above.

HTH

Does your UFH have multiple zones with actuators and a UFH controller?

Edit: actually, I'm thinking of it as having a system boiler (with integral pump).
If yours is different then a system layout is required. Where exactly is your system pump in the scheme of things?

 

[milgo123]

My UFH will be installed in the coming weeks. 1 zone with 2/3 loops. No actuators. No UFH controller
Programmer/clock will Drayton Wiser 3 channel.

 

[dilalio]

My UFH will be installed in the coming weeks. 1 zone with 2/3 loops. No actuators. No UFH controller
Programmer/clock will Drayton Wiser 3 channel.

And the manifold you're getting?

 

[milgo123]

Sorry but that I do not know yet. I plan to have a sit down with the heating engineer/plumber in the next week or so to go over what I think that I need/want and what he suggests that I have installed.

Any do's or don't that you could offer would of course be very helpful.