Looking at the board with two relays on it looks like one relay drives the domestic hot water pump and the other the central heating pump which makes sense. However, other models of SYMSI7.0 can have three or four relays so what would these additional relays be driving?
I'm trying to change the control board in my boiler (because I periodically get a fault code).
The controller is a SYMSI7.0 but I notice on the web that there are slightly different part numbers e.g.
0310144400015 <- my original board
Eyeballing these boards the...