Replacing Drayton LP241 with Drayton Wiser - Combi Boiler

[SomeoneElseDoIt]

Successful upgrade to Wiser, here are the details in case it helps anyone else.

I had a Drayton LP241 which used to control a dual channel system (hot water and central heating). A few years ago I had the boiler replaced with a Glow Worm combi, but did not replace the controller, so the hot water channel would appear to operate if switched on but in fact did nothing.

I bought a Drayton Wiser WT714 which is the single channel combi version. Thought it would be a drop-in replacement, but not quite.

Glow Worm requires live switched central heating ON signal. LP241 put this out on pin 4:

But the Wiser puts it out on pin 3 AND it isn't connected to the LIVE by default:

Here's my original backplate wiring:

So, to make it work, I needed to:

a) move the yellow wire from 4 to 3
b) add a link wire from LIVE to 1

I also moved the yellow from 1 to 4, which the Wiser does not use. I figured this would be better than putting permanent mains on the old hot water demand line, which was presumably disabled and terminated by the fitter who installed the combi. No biggie, as the LP241 would put mains on 1 if I accidentally pressed the hot water button and I never heard a bang.

I left the original thermostat in place but turned up to 30C, as I guess the CH ON signal from the backplate goes through the thermostat on the way to the boiler, and therefore is switched by it. One day I will get round to tidying that up.

 

[CountryFan]

So it seems this just a helpful post then?

 

[ericmark]

Picking a random glowworm boiler, I see there is an ebus option.

As to if worthwhile, I don't know, I think there are conversion modules, so could use OpenTherm, but I have noted many boilers are far too large for the radiators they supply, need around double the radiators size to boiler fitted, as we tend only to heat one floor at a time.

I fitted Wiser with simple on/off oil boiler, very pleased with it, I note now the boiler is being called to heat up wife's bedroom, even when living room is up to temperature, which is exactly what I wanted, the Wiser is very well suited for the larger house where we don't want all rooms heated together. As you can have multi thermostats.

 

[SomeoneElseDoIt]

So it seems this just a helpful post then?

Yes, I should have made that more clear. I posted because I searched a lot and couldn’t find my problem, so thought it might help others in the same situation.