Cylinder stat connection on vaillant VR6x's -?

[Googlyhead]

Seems to have been a few people on this forum setting up these! They're never configurable enough, are they?

Anyway; can anyone tell me if it's expecting a stat to close on temperature, or open? Any configurability?

If you (ok; I) were to use the tank stat as a failsafe for a vr10, would it be best directly wired to the valve?

Any cheap suppliers for the VR10? or an alternative (2k7 NTC, I believe) probe?

TIA!

 

[Googlyhead]

Oh, whoops. I also meant to ask; is there any problem with using this connection as a cylinder 'call for heat', alongside the temperature probe?

 

[UpgradeME]

Anyway; can anyone tell me if it's expecting a stat to close on temperature, or open? Any configurability?

I assume you are referring to a cylinder thermostat connected to the VR6x? - Having looked at the wiring diagrams (and recently fitting a VR65) it's not clear if the cylinder thermostat should be wired normally open (NO) or normally closed (NC) and there are no options that I am aware of to change it (besides wiring the thermostat to the other terminal)

I can say that if you are using a NTC (such as the VR10), you DON'T wire up a cylinder thermostat to the VR65, the NTC is used INSTEAD to 'switch off' demand for HW via the VR65 when the set temperature is reached.

If you (ok; I) were to use the tank stat as a failsafe for a vr10, would it be best directly wired to the valve?

On my installation which I use the VR10 NTC to control DHW temperature, I also wired in a cylinder thermostat as an additional safety cut-out, in-between the HW valve and the VR65. This is wired as NC so if the tank ever reached over 75C (temp set on cylinder stat), it will cut the power to the valve, which is spring loaded so will close.

Any cheap suppliers for the VR10? or an alternative (2k7 NTC, I believe) probe?

I don't know about the other VR6x units but a VR10 is supplied in the box with the VR65. A quick google reveals this site claiming to be the cheapest on the internet selling VR10's for £15.45 + VAT each.

 

[Googlyhead]

I assume you are referring to a cylinder thermostat connected to the VR6x? - Having looked at the wiring diagrams (and recently fitting a VR65) it's not clear if the cylinder thermostat should be wired normally open (NO) or normally closed (NC) and there are no options that I am aware of to change it (besides wiring the thermostat to the other terminal)

Yep. Cylinder thermostat. I guess I can always experiment to find out, but it would have been nicer of them to tell you in the docs!

If you (ok; I) were to use the tank stat as a failsafe for a vr10, would it be best directly wired to the valve?

On my installation which I use the VR10 NTC to control DHW temperature, I also wired in a cylinder thermostat as an additional safety cut-out, in-between the HW valve and the VR65. This is wired as NC so if the tank ever reached over 75C (temp set on cylinder stat), it will cut the power to the valve, which is spring loaded so will close.

That's pretty much the plan. Only; if the valve is shut, and the VR65 doesn't know it (no connections for the switch wires or any other input), it's just going to keep trying to put heat in. That's why I was considering using the VR6x's connection instead (or as well).

VR10's for £15.45 + VAT each.

Delivery is better there, but the actual part is half the price at bhl and mytub (another quick google!) I know there'll be a mark-up for branded equipment, but a basic NTC shouldn't be in the double figures??!?

I appreciate the input; thanks! I was beginning to wonder if I should have posted over the weekend or something!