Update: i found a flaw in my plan to use a 24v adapter combined with the potential free input of the proliphix. pointed out by akatar and found in the manual you read that the common needs to be the same fase as the RH. if i use the adapter i use two fases to feed the proliphix. one fase where the vaillant is connected to and one from the adapter in the livingroom. so this should give me problems with my fuses/earth leakage.
the googling continued. i though about a famous other thermostat called nest and found out it needs a common wire to. combining this in my search with vaillant i found a post which told me the teminal 3 in my kettle was possitive, 4 was the switching cable and 5 (before a mystery) should be negative/common.
i measured this and it looked right. so i took the risk and connected three wires to the proliphix. rh to 3, w1 to 4 and c to 5, and it is working fine!!
hope this helps some of you. there a still some philiphix nt120h for sale on ebay. and they are not that expensive (i paid €130 incl shipping).
good luck!
Proliphix nt120h how to connect to a Vaillant ketel
Moderator: hvxl
Last edited by Phaeton on Sun Oct 28, 2012 11:16 am, edited 1 time in total.