Vaillant Controls

16 Sep 2011
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United Kingdom
I'm trying to hook up a fairly standard two zone weather compensated Vaillant control system, with ecoTec Plus 438 / VR 430f / VR 61 / VR 81 - just two on/off zones (upstairs and downstairs) with two port valves and a conventional cylinder with a two port valve. Exactly as in VR 61 hydraulic drawing 4.

My problem is there seems to be a disconnect in the Vaillant documentation - not a surprise to members of this forum, I suspect. Where do I connect the tank sensor (SP 1)?

The VR 61 installation instructions say that it connects to the "wiring harness of the heating equipment," which I assume means the boiler. "(see documents which also apply, installation instructions heating equipment)" which I assume is a rather poor translation of "see the boiler installation instructions." They, however, make no mention of where to connect the thing.

I guess I could ask Vaillant, but reports here aren't terribly encouraging and I already have one unanswered email.

Then when I've got that hooked up I can try to work out why the vrDialog won't connect.

Any help gratefully received.
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did you find a solution, I've got the same problem, Vaillaint engineer also confused.
Yes I did. Should have posted it I suppose.

If you look in the installation manual for the 6xx-8xx boilers, in diagram 4.17 there is a "Tank NTC Connection" that goes into connector X2 pins 4 and 10. This is where the sensor needs to go. Its quite tricky to connect because there is already a plug on X2, but with vacant holes. I couldn't get the correct pin type but managed to substitute a pin out of a broken DB25 RS232 connector. I seem to remember pin 10 is an earth so you can use one of the earths on X41 for one side. You have to connect into pin 4 on X2 for the other side though.

This seems to have done the job perfectly.

I asssume if you are a Vaillant engineer though, you can probably get hold of a kit witht the required pins and a lead to a proper connector.

I'll be interested to hear how you get on because I've found a few other ways in which this design seems to be a bit unfinished.
The vr10 semsor does go back to the boiler as the wiring diagram says.
There is a special plug available for this connection to make the connection possible on the 400 series ecoTEC. Your suppliers merchant may be able to obtain it for you, i'll try to find out how else it can be ontained when I start work tomorrow and post it.
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In order to fit the standard NTC sensor (VR10) to the ecoTEC plus open vent boiler an additional harness is required (as shown below) this can be obtained by getting your installer to contact Rochester Technical department and ask for the ecoTEC open vent, cylinder NTC harness.
The harness is connected to plug X2 on the main PCB and replaces the existing plug.
The VR10 sensor can now be fitted to the connector blocks.
Important Note: cylinders in the two-zone heating system can only be controlled using an NTC sensor VR10. The cylinder must have a suitable positioned dry pocket, such as the Vaillant uniSTOR cylinder.
many thanks. I have a ecotec624 system boiler, but it's still figure 4.17 and pins 4 and 10 on X2. I don't need the harness pictured, but I do need a 2way connector that mates with the 2way connector that's attached to X2. In the meantime I've jammed in the leads from the VR10 and secured with pvc tape. And now my hot water works from the vrc430 :) happy days, no more manually moving the valve everytime we want to heat hot water. Vaillant should be ashamed of themselves, can't see any reason why the connector is not supplied with the VR61/65 along with proper instructions.
The 600 series is different. It has an orange and black lead with a plug on the end that already exists on the harness in the left side. You snip the plug off and use a block connector to connect the sensor.
I installed a bit of connector block as a final fix, everything running fine now for past few months, many thanks.

On a similar topic, I'd like to add a GSM switch so I can control the heating from my mobile. The GSM switches available have two relays, these can be switched by calling, or by text message. They can be connected as normally open or normally closed.

My questions are, can I connect one GSM relay across two terminals of my ecotec624/vr65 such that when the contacts are closed the heating will switch on regardless of the settings on the VRC430 ?

Can I connect the other relay inline with something such that if the relay opens, the heating will switch off regardless of the settings on the vrc430?

and if yes, what are the terminals I need?

this is to allow remote operation to deal with situations where I decide to stay away from home, or return home early from a holiday. Simultaneous control of the DHW would also be an advantage to have the bath water ready :)
I realise this thread is really old but is there a part number for that ecoTEC open vent, cylinder NTC harness? I note that if installing a VR65/VR66 the VR10 for the cylinder is installed in the wiring box itself but when using the VR61 the same VR10 for the cylinder is wired directly to the boiler. So does anyone know if I don't use the VR65 VR66 or the VR61 and simply wire the VR10 directly to the boiler, will the boiler be able to detect the cylinder temperature?
The part number for that harness is 0020247021.

Using the wiring harness above you can connect the NTC VR10 of the cylinder directly to the boiler even while using wiring centres like VR65 or VR66. Just thought I'll mention this as this provides an alternative to wiring the cylinder sensor only back to wiring centre as per the instructions.
Just don't try wiring a NTC to boiler without the any controller connected, it kicks the boiler into a HW heating cycle even though the controller isn't connected and there is no actual demand. But if you ever needed just the controller and the cylinder temperature sensor, you dont need a wiring centre if you had another method to controlling the motorised valves.

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