Wiring up combi for s-plan

[omph]

Can someone provide guidance on this topic ? I'm not asking for any particular brand, but just trying to wrap my head around where I would hook up the two zone valves in the combi and the two thermostats.

 

[kidgreen61]

The zone valves will have a orange and grey wire, you need to figure out how to use those as your volt free contacts to your combi in order to make it fire.
Scribble it down on a scrap of paper, to simplify, 240v to brown wire to switch zv on, then orange and grey to make combi switch on.'
Please don't send 240v to combi

 

[MNW67]

Does this help?

Combination Boiler with 2 Heating Zones, Volt Free Switching

Wiring diagrams for a combination boiler with two separate heating zones using volt free switching

flameport.com

 

[dilalio]

As above... First determine if you are switching volt free or 240V.

 

[RandomGrinch]

Can someone provide guidance on this topic ? I'm not asking for any particular brand, but just trying to wrap my head around where I would hook up the two zone valves in the combi and the two thermostats.

Sorry, may I just clarify what you want to do?
As you are saying two thermostats and two zone valves, do you mean you are setting up a dual zoned heating system on a combi; or are you converting a combi system to an S plan, including a new hot water tank and associated plumbing modifications?

 

[omph]

Sorry, may I just clarify what you want to do?
As you are saying two thermostats and two zone valves, do you mean you are setting up a dual zoned heating system on a combi; or are you converting a combi system to an S plan, including a new hot water tank and associated plumbing modifications?

Well, I would have thought one thermostat for the heating and another for dhw.

 

[RandomGrinch]

Well, I would have thought one thermostat for the heating and another for dhw.

Ok, so it seems as if you are intending to create an S-Plan system with a hot water tank, but instead of being supplied by a system, or heat-only boiler, it will be supplied by a combi (or do you mean a condensing boiler instead of combi)?

Usually in an S-Plan system, there is a tank thermostat on the water cylinder and the programmer controls the timing of the hot water.

As linked earlier, Flameport has a good primer on S-Plan...

S Plan central heating system

S-plan central heating system operation and wiring diagram

flameport.com

 

[MNW67]

just trying to wrap my head around where I would hook up the two zone valves in the combi and the two thermostats.

If you have only ever had a normal combi set up before, then I thought I should mention something basic to start with. With an S-plan, the thermostats and zone valves don't hook up directly into the boiler. You need a wiring centre. All the zone valves, thermostats, programmers etc. get connected together in the wiring centre. And then a wire goes from the wiring centre to the boiler to turn it on and off as required.

 

[Stuckinarut]

If it is indeed a combi, unless you want zonal heating, then the thermostat would usually get wired into the pcb of the combi boiler. A little clarification would be best here.

 

[omph]

If you have only ever had a normal combi set up before, then I thought I should mention something basic to start with. With an S-plan, the thermostats and zone valves don't hook up directly into the boiler. You need a wiring centre. All the zone valves, thermostats, programmers etc. get connected together in the wiring centre. And then a wire goes from the wiring centre to the boiler to turn it on and off as required.

are there any particular types of junction boxes you'd recommend ?
Also, how would one manage the temps for the CH and DHW ? newer combis allow for more refined settings for CH and DHW temps like weather comp.

 

[dilalio]

Will you still be using the instant hot water supply of the combi to feed a utility room or kitchen or something?

I am getting the impression that you're not getting this so can you confirm you are having a hot water cylinder or not?

Then we'll all be on the same page.

 

[flameport]

are there any particular types of junction boxes you'd recommend ?

This or similar: https://www.toolstation.com/drayton-wiring-centre/p19346

Also, how would one manage the temps for the CH and DHW

Thermostats - a room thermostat which senses air temperature for the CH
and a cylinder thermostat attached to the hot water cylinder for the DHW

Most of it is the same as connecting any other boiler to a heating system and hot water cylinder - the only difference is that a combi boiler can also do hot water on demand, and the added complication that some combis don't use 230V switching so a slightly different wiring arrangement or a relay may be needed.

newer combis allow for more refined settings for CH and DHW temps like weather comp.

Newer boilers in general have such features, they are not just for combination boilers.

 

[MNW67]

Newer boilers in general have such features, they are not just for combination boilers.

If you are using a combi with a hot water cylinder, can you set it up to do PDHW so that you have different flow temperatures for CH and DHW?