FAO - John Rumm - Heating temperature split, Vaillant

I did see some mention of the VR66 somewhere, but could not track down anything further on it or find a manual.

That reminds me, I never did get a response to my question about the system losing date and time on a power cut...

(it remembers its programming, but not the date and time which is annoying when it decides that the middle of the night is now a good time to run the heating)

on 14/01/2019, John Rumm supposed :

A failing NiCad?

Once it has internet connectivity all that will be a thing of the past.

John Rumm submitted this idea :

Still no answers from Vaillant 'TechHelp', despite restating my original question in simpler language - it seems if the answers not on their crib sheet, they just make a guess or completely ignore the questions.

I have on order a VCR 470F complete and a VR65 Control Centre. Having studied it a little more, its obvious that the VR65 couldn't possible work alone, without another Vaillant unit to instruct it what to do. It will not accept commands from my present room stat, or respond to the time clock. Wish me luck!

Harry Bloomfield wrote on 15/01/2019 :

Oh, the F wireless version, seems to have a DCF receiver built into it, so no need to set the time/date anyway.

Harry Bloomfield laid this down on his screen :

TechHelp has just replied again, but without actually answering my question will the VR66 + VRC 470 work with my Y plan system. They have again just said they are obsolete and I need a VR66 + VR700.

I have now emailed them a third time. It does make me wonder if a computer is answering the Tech questions...

I get the impression that the date and time is recorded in the boiler rather than the controller.. but I have not had anyone confirm that.

I have a feeling there is only one way you are going to find out :-)

John Rumm pretended :

I would not expect that to be the case, because the boiler lacks the means to keep the clock running and I cannot see anything in my boiler's menu for clock setting. The timer/controller (470) is the obvious place for time / date to be stored, where it is used.

John Rumm expressed precisely :

lol

on 16/01/2019, Harry Bloomfield supposed :

John, whilst I am waiting for delivery, I might as well install the ebus cable. Is there a spec. for this cable, twisted pair or what - or would ordinary twin flex or bell wire do. It will be a run or around 5 yards, from boiler in kitchen to the VR65 in the airing cupboard.

It happens that John Rumm formulated :

I managed to find a manual for the VR 66, it seems the same unit as the VR65, but includes an option for two heating zones, rather than the one of the VR65.

That is where you set it. But if you power off the boiler, it loses the date and time, but retains all the other programming...

Having said that its hard to separate them, since powering off the boiler also deprives the 470 of power.

I had lots of thin PVC mains flex on a reel, so used that (probably "3A" flex). It seems to work fine over much larger distances. Some of my runs must be over 25m (like the external temp sensor to the boiler).

Oh, also don't know if its still the case, but the boiler end of the connection for the cylinder NTC sensor had a two pole connector fitted to it, and I could not find a supplier of a matching connector, and one was not supplied with the stat kit for the cylinder. So in the end I chopped it off, and used a couple of "jelly bean" style IDC connectors. That seems to have worked just fine.

Ah, ok. Seems like the modern version of my VR61 then.

John Rumm explained on 16/01/2019 :

Thanks, somewhere in the garage, I remember I had some long lengths of two core flex - that should do it.

The VR65 instructions suggest it will accept its temperature input from a normal switching stat, or an NTC. It also suggests the NTC can only be used with the Vaillant Unistore cylinder - I don't quite follow the logic behind that, an NTC should be able to provide a much more accurate HW temperature than a cylinder stat.

Yup can't see why it would only work on a unistore (mine *is* a unistore, but its not bespoke or integrated with the boiler - it would work in any setup). I does have a pocket for the NTC to slip into, but I expect it would work as well if tucked under the insulation against the wall of a conventional cylinder.

If the VR65 has provision to take the stat connection, then that is a step up from the VR61... (where I had assumed that it would work like that, and then ended up needing to install another cable run at the last minute)

That was my thinking, except the VR65 manual says the NTC sensor - 'is only for use with the OptiSTOR). It has terminals for a stat or NTC, but no clue as to how it decides which it should use. VR65 turned up this morning and complete with the NTC.

I'm just taking a break from getting the extra ebus cable in from boiler to airing cupboard.

The NTC thermistor is a less usual 2.7K .