switching relays board

[scubammx]

Hallo dear guys , i hope someone could help me , i am from italy and i have emonbase raspberry, emontx and emonth .
I would like to drive a relay board on certail circunstances, like open valves of the heat floor in some rooms at a certain temperature, turn on the garder lights at a certain time and so on ...
Can someone suggest me how to move ? I have basical skills on programming and i installed the openenergymonitor with no trouble, but i dont know which way to follow to switch the relays, i would like to use the RPI i already have in the emonbase, but i am afrait ti make a mess on the current firmware, so i could accept to buy and setuo another RPI or arduino , important is that i need to get the 433mhz feeds from the current nodes...
hope someone could help me ...