Vaillant ecotec plus 418 Boiler wiring problem

[Rayscho]

Help required with the wiring of a Vaillant ecotec 418 Boiler.
No 4 terminal on the PCB: should this be voltage free ie the switched live for the boiler, as this terminal has a negative feed when checked with a meter.
can anyone help with this problem

Thanks in anticiption

 

[mickyg]

240v switched live into boiler.

 

[Rayscho]

Thanks for the reply, however when connecting the switched live to the No 4 terminal, the House rcd tripped. Checked No 4 terminal and found that when meter connected to Line +Pos (Boiler) and No 4, meter read 230 Volts, therefore it appears that the No 4 terminal is getting a Negative feed through the pcb.
Again any help would be appreciated.

 

[Kristoflampie]

Have you removed the link between 3 and 4 ?? The link must be removed before any external controls are wired into the boiler. These boilers are either volt free through a volt free switched clock or room stat using both 3 and 4 as the switch circuit or by wiring the switched live output from the external controls straight into 4 (1 live wire, no neutral). If you are tripping the rcd there is some problem with your wiring. Switched live comes from whatever version of zone valving you have.

 

[Rayscho]

Again thanks for the reply, the Pos live switched feed is from the zone controls, however the No4 terminal has a negative feed through the pcb. Therefore when the switched feed is connected to No4 there is a dead short and the rcd trips.

Any help appreciated.

 

[Kristoflampie]

Just checked and 4 is definitely the right terminal for a 240v feed from external controls with link removed. remove the switched live wiring from 4 and switch boiler power on, test terminal 4 for 240v , it should have nothing if tested with a neutral or earth on the other meter probe. If it has 240v there is a fault with the pcb, if it still trips the rcd you have an external wiring fault

 

[gas4you]

Remove your wire to terminal 4, then re-instate the link between 3 and 4.

If your RCD/trip still blows then there appears to be a fault on the board. If not it is a fault in the external controls.

What about the pump? This is controlled by the pcb. Try removing this from the equation, or testing with your multimeter

 

[namsag]

Do what dave suggests first but What external contols do you have is it 2 two port valves or a mid position. pump should be wired back to boiler terminal position for all installs.

 

[simond]

You will get 230v dropped across 3 and 4.

For reasons which are obvious.

If you are tripping out an RCD you do not have a short between L and N.

You have an earth leak somewhere.

Whilst it is probably an external wiring fault, we had an early 4 series with strands of metal swarf in the PCB enclosure, which caused a similar problem.

The 'British Vaillant' syndrome....

 

[Rayscho]

Thanks for the info. Simond right, problem was an earth fault on the switched live.
A small nib of wire protruding from a row of Choc boxes earthing onto the metal patress box. Problem solved.

Thanks to all who wrote in.

Cheers Ray