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Discuss Combi boiler and zone valves help in the Central Heating Systems area at ElectriciansForums.net

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Hi chaps
I’m wiring up a 2 zone heat system to a combi boiler.
Do I need to replace the boiler mains cable with a 4 core cable and remove the link wire to s/L? I’m unsure how to run switch live from the zone valves and still keep the combi water side of it going? Any help would be appreciated
 
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bill01803

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The boiler should already have a permanent live, just take a live to switch in valves and use this to switch boiler
 
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There are a number of methods, much depends on the boiler, for an opentherm boiler you can use EPH thermostats which can be connected as slave and master to control boiler with an analogue signal but control zone valves on/off.

The Drayton Wiser system also has a programmer/thermostat system designed for twin heating zones. And has a opentherm module.

If the boiler is not opentherm enabled then thermostat work the zone valve and zone valves work the boiler.

This assumes a traditional zone valve, clearly a thermostatic radiator valve (TRV) also forms zones, and by using electronic heads they can also be programmed, and can tell the boiler what to do either by return water temperature or by wireless connection to a wall thermostat/hub.

Some work in reverse where wall thermostat/hub tells the TRV head what to do. And with fan assisted radiators control is by adjusting fan speed, and they can also be used to cool.

Since we have no info on boiler or system it is guess work, @bill01803 is correct with most systems, but since we don't know we must advise read the boiler manual.
 
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There are a number of methods, much depends on the boiler, for an opentherm boiler you can use EPH thermostats which can be connected as slave and master to control boiler with an analogue signal but control zone valves on/off.

The Drayton Wiser system also has a programmer/thermostat system designed for twin heating zones. And has a opentherm module.

If the boiler is not opentherm enabled then thermostat work the zone valve and zone valves work the boiler.

This assumes a traditional zone valve, clearly a thermostatic radiator valve (TRV) also forms zones, and by using electronic heads they can also be programmed, and can tell the boiler what to do either by return water temperature or by wireless connection to a wall thermostat/hub.

Some work in reverse where wall thermostat/hub tells the TRV head what to do. And with fan assisted radiators control is by adjusting fan speed, and they can also be used to cool.

Since we have no info on boiler or system it is guess work, @bill01803 is correct with most systems, but since we don't know we must advise read the boiler manual.
Thanks chaps
It’s sorted now I was 90% there just couldn’t figure out the boiler connections, I replaced the boilers 3 core cable with a 4 core and used the extra core to go to the switch live on the boiler and then to the orange wires in the wiring centre, I also ran a link from permanent live to switch live on the boiler controls to give it a common feed.
The boiler is a ideal logic and I’m using 2 google nests one for each zone.
 
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From internet hunt said:
Ideal Logic boilers have OpenTherm wiring connections meaning operation is optimised when an OpenTherm room thermostat or programmable room thermostat (PRT) is connected. ... It also maximises room comfort as the boiler output is reduced as the set temp is approached, so reducing overshoot and unnecessary overheating.30 Oct 2019
However unlike EPH and in fact most other smart controls, Nest does not work with any other units or as pairs using OpenTherm. So in real terms should only be used as a single unit.

As on/off you can use as many thermostats as you want, but with zone valves the normal is to control the zone valve with the thermostat, then the zone valve controls the boiler.
 

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