Vaillant Turbomax 242 problem permanently on

Joined
5 Jan 2008
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Location
Berkshire
Country
United Kingdom
HI all,

I have inherited a Vaillant Turbomax 242, and have come across an interesting problem which only manifested itself as the weather got colder, as the switch in the boiler was previously turned to DHW only, but now is turned to the DHW+CH symbol ....

The CH seemed to be permanently on, and the programmable timer (external) did not seem to make any difference to the functionality of the boiler. The timer was extermely gooey with grease etc, and had loads of dead insect remains in the casing, so I figured it might be dead itself, and bought a replacement. Took the old one off, plugged the replacement straight in, married the pins into their slots, should only need to change the front electronic bit, no need to touch the wiring, all of 2 min job .... problem fixed?? NO!

Further investigation revealed that the Neutral and Live from the cable coming from the boiler were connected with the Neutral and Live pins on the electrical feed in - hence surprise surprise the boiler is always on! DHW obviously only fires up when a tap is switched on, but CH is always on and ignoring timer programs/instructions. SO, worked out why the problem really occurred. Now to work out how to fix it.

Checked the wiring diagrams on the new timer, and worked out the correct wiring. On connection, the CH did indeed work according to timer instructions, but now the DHW only came on when the CH was on, otherwise dead. Now what?

Checked wiring in the boiler, and for some reason, only the earth, live and neutral are connected, three of the 6 wires in the cable had been cut off and were present but not connected in the boiler. With that limited connectivity, not surprising that all the boiler knows to do is to switch on and off without differentiating between wanting DHW or CH!!!

So to my question.

Can anyone provide me with the wiring diagram for the Vaillant Turbomax 242 boiler so I can reinstate the wiring between the boiler and the external timer as it should be. If possible, can anyone provide me with an electronic copy of the manual for this boiler? The other option is to purchase the integral timer for this boiler and discard the external one, but even this might not work as the whojamacallit who did the wiring for the external timer might have decided to somehow disable this apparently useless internal optional functionality of the boiler!!!

Hopes you can help, TTFN.
 
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