Y plan heating system. Boiler Change Problem.

[v.elec]

Hi people.

Here's one for you.



Problem with a boiler change. Engineers changed an Ideal FF250 classic system boiler, to an Ariston Evo System boiler. (System boiler to system boiler)

FF250 classic is 3 wire boiler and all that there is a 3 core flex which went into L N E (L being switched live from 3 port valve basically).


For the new boiler, it requires a Permenent Live, Neutral & Earth from the 3A FCU, so I done that. The existing 3 core I was talking about can now be connected to SL on boiler. Simple...

However, no SL. AKA, no 230 volt switched live at all. The boiler terminal for the switch wire are 24 volts or voltage free. Now, I know it is possible on an S plan heating system to use the grey and orange on the 2 port valves as the volt free connections.


But how on a three port valve? Stumped.

Thanks if you can help.

 

[jaydee81]

only way you can do it with y plan is by doing low voltage switching trough a relay

 

[Spark1979]

It tells you in the boiler instructions that you'll have to use a relay, But it is suggesting that a y plan system isn't ideal, also if it's got a unvented cylinder you must have a two port valve before the cylinder, hence instructions telling you to put 2 2 port valves in

NOTE: THEUSEOFA‘Y’PLANSYSTEMISNOTPOSSIBLEWITHTHECLASHE SYSTEM BOILER DUE TO THE LOW VOLTAGE SWITCHING OF THE APPLIANCEUNLESS SUITABLE RELAY CONTROLS ARE USED.