Let me explain the concept...
Intergas boilers are brilliant in the fact they are a simple, really well designed boiler and use load compensation technology (as standard) in the form of OpenTherm. Intergas realised that when using low flow temperatures (thanks to load compensation), calling for hot water demand to charge an external cylinder would need to be at a higher flow temperature (otherwise the cylinder just wouldn't get up to temperature required!).
Intergas therefore designed their boilers so when there was a DHW demand, the boiler could operate an external 3 port diverter valve (or in our case 2x motorised zone valves that make 'X Plan') to shut-off the supply to the heating circuit and open the supply to the hot water cylinder. But ever so slightly better than this, when the boiler activates for hot water demand it also knows to use different kW output settings and flow temperatures for hot water from when it was controlling central heating!
However, the evohome system can independently and wirelessly control heating and hot water when using an R8810 OpenTherm Bridge without using Intergas 'Pin 5', but this is at the disadvantage of using the only the boilers central heating settings, which won't be optimised for hot water recharging.
There is however a way of using 'Pin 5' hot water and evohome!
You need the minimum following items. All these items can be purchased from The INTERGAS Shop (https://theintergasshop.co.uk) using the relevant part numbers in brackets () below.
1x Intergas Cylinder Sensor (065117) wired to the boilers X4 connector pins 9 & 10 and fitted to the thermostat pocket of the cylinder via the DHW BDR91 (and High Limit Thermostat if fitted)
1x Honeywell (V4043H) Normally Closed 2 Port Motorised Zone Valve fitted to cylinder pipework
1x Honeywell (V4043B) Normally Open 2 Port Motorised Zone Valve fitted to heating circuit pipework before any branch offs to UFH or radiator circuits
1x Honeywell evohome Modulation Pack (ATP951M3118) connect the Honeywell R8810 OpenTherm Bridge to the boilers X4 connector pins 11 & 12
1x Honeywell evohome Hot Water Kit (ATF500DHW) fit Honeywell CS92A at the cylinder location and put insertion sensor in the same thermostat pocket that the Intergas Cylinder Sensor is fitted to. Then wire the Honeywell DHW BDR91 to the boiler as per the wiring diagram below instead of the 'X Plan' post - http://theevohomeshopforum.co.uk/viewto ... =22&t=3985
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