Replace TP5 with Vaillant 380f - wiring question

[SpinneyMike]

I have a Vaillant Ecotec plus 831 with a Danfoss TP5.
The electrical connections are via a five core cable. I believe three
(live netural and earth are mains supply and the other two to Danfoss)

I want to wire in a Vaillant 380f wireless and believe that is simple -
2 wires from EBUS to new unit.
The danfoss is connected to the 230v purple RT and mains supply terminal in the boiler.
Two questions. Can I simply remove the the two cables connected to the Danfoss from the purple RT and live block
and connect them to the eBus and then connect the new receiver where the danfoss is now? Or will this risk induced current?
Ideally I would like to place the receiver/sender where the TP5 is now

If not, do I just run two connectors to the ebus and then disconnect the danfoss or leave it alone.

Obviously i would need to reinstall the link cable to make ebus work.

thanks in advance

 

[CBW]

I think the Vaillant receiver is a plug in type, so plugs into the front of the boiler. Yes you can use existing wiring but you MUST disconnect all of the mains side for the Danfoss and then only use the 2 remaining wires for eBus, but you will need to run wires iirc for the thermostat to work? Also removing the caps on that boiler forms part of the combustion circuit so would need to be checked for safety afterwards.

 

[SpinneyMike]

Thanks Chris, Yes it has the possibility of plugging on but only on boilers with a socket! the ecotec plus 831 doesnt (as far s I can see) so it will need wiring separately. the control unit is RF

 

[CBW]

Post a photo of the boiler front

 

[SpinneyMike]

Sorry - its a Vaillant Sensohome VRT 380f

 

[SpinneyMike]

It would end up like this. the black and grey currently to to the purple RT and live. the pic was downloaded from elsewhere

 

[SpinneyMike]

Worked it out now - all seems to be running ok Procedure as follows

Boiler off at mains
open boiler, disconnect existing thermostat connections at PCB (two wires one 230v mains, other RT)
run new heat resistant 0.75 two core to ebus,
connect to sender receiver mounted in boiler cupboard
REMOVE EXISTING TIMESWITCH IN BOILER!
power up controller and follow installation assistant
close up boiler and have checked for gas safe
operate!

At first, I didnt remove the existing timeswitch and it behaved erratically.

It now works as it should. fingers crossed...

 

[SpinneyMike]

 

[ianmcd]

you will have to remove the red link in 24v RT or the boiler will not go off

 

[SpinneyMike]

mmm..its... its off now (no burner or pump) and the red link is still there - in fact its always been there - even with the danfoss TP% connected... ???

 

[SpinneyMike]

Just the waiting symbol flashing - egg timer. thermostat not callin for heat.

 

[SpinneyMike]

Now the wait symbol is gone ( I lowered the thermostat by one degree) boiler all quiet, no boiler, no pump - in fact if it wasnt for display, I would think it was off at the wall.

 

[SpinneyMike]

Just checking the manuals - the only time I can see the burner off bridge is removed is when setting a ceiling temp. for underfloor heating thermostat. I am going to leave as is for now.

 

[CBW]

you will have to remove the red link in 24v RT or the boiler will not go off

Actually mate, I think it’s required

 

[SpinneyMike]

Yes - the 24v RT bridge which is definitely needed ( I tried it with and without) I thought he was talking about the burner off bridge, my mistake.