Vaillant VRC 430f cycling issues - a solution?

[smokebox]

unless you have a VR81 and VR61 installed keep the VRC430 set to 'Thermostat'

This is an interesting observation. Are you saying that "Thermostat" as opposed to "Modulating" definitely works better for preventing cycling if you are running a single CH Zone?

But with 2 zones (implied by VR 61 and VR81) "modulating is better, or at least no big difference?

smokebox

 

[JoeMar]

unless you have a VR81 and VR61 installed keep the VRC430 set to 'Thermostat'

This is an interesting observation. Are you saying that "Thermostat" as opposed to "Modulating" definitely works better for preventing cycling if you are running a single CH Zone?

But with 2 zones (implied by VR 61 and VR81) "modulating is better, or at least no big difference?

smokebox

hi
as i understand it yes, with only the VRC430 installed, set it to 'Thermostat'

i think word 'modulating' is misleading here, hence why they've changed it to 'room switching' in the manual. maybe someone with a new VRC430 can confirm if they have renamed it on the unit as well.

i would like think that 'modulating' is better with 2 zones as it will be comparing 2 room temperatures instead of 1 in 'thermostatic' mode. in my mind all of this makes sense when one of the zones is controlled via a motorised mixing valve via the VR61.

 

[smokebox]

hi
as i understand it yes, with only the VRC430 installed, set it to 'Thermostat'

i think word 'modulating' is misleading here, hence why they've changed it to 'room switching' in the manual. maybe someone with a new VRC430 can confirm if they have renamed it on the unit as well.

i would like think that 'modulating' is better with 2 zones as it will be comparing 2 room temperatures instead of 1 in 'thermostatic' mode. in my mind all of this makes sense when one of the zones is controlled via a motorised mixing valve via the VR61.

Joe thanks
Hmm
My house is large (24 rads and 2 quite big cylinders) with 428 open vent, eBus VR430, VR61, VR81. This lot controls zone valves for 2 CH zones (2 port each valve), and a two 2 port zone for the cylinders which are essentially run in electrical parallel.

Thus not quite as you depict in your system, but close, though hard wired, not radio. I take it your vr430 is not boiler mounted!

The VR430 is pretty new ("mytub" internet) about June - software number 2.15, just connected up 2-3 days ago. Wall mounted downstairs in zone 1 (HC1)

The paper instruction manual talks of "none, modulating,thermostat" as options [without explanation of course!] under C8 screen description.

The VR 430 itself talks exactly the same words (unusually!)

Oddly the default factory is "none". I wish they were a bit more explicit about what to expect of these options.

The VR61 (same age of purchase - software number 2.11) in C8 for HC1 talks of "none, intervention, thermostat " options. These are repeated in C10 for HC2 setting.

The soft ware [vrDIALOG 810] under the VR61 tab> extra tab> heading HCI_RoomControlMode talks of "off, modulation,Thermostatfunction"
while under the VR430 tab> extra tab > heading "HC2_RoomTempSwitchON" talks of "off, modulation,Thermostatfunction".
I am being as accurate as possible as the changes in text used all suggest possible software changes in the various components of the control items. Or you could surmise some lack of clarity of thinking somewhere!

I am using the modulation setting for both zones, and usually all goes well. I have raised the minimum target to 30*C though it was not too different on the preset 15*C as I recall.

Iam interested in your idea of the algorithms comparing the temperatures between zones and using that as well in the calculation. Can you expand?

All very interesting, but might get to be irritating eventually!

smokebox

 

[David937]

unless you have a VR81 and VR61 installed keep the VRC430 set to 'Thermostat'

This is an interesting observation. Are you saying that "Thermostat" as opposed to "Modulating" definitely works better for preventing cycling if you are running a single CH Zone?

But with 2 zones (implied by VR 61 and VR81) "modulating is better, or at least no big difference?

smokebox

Maybe someone with a new VRC430 can confirm if they have renamed it on the unit as well.

I got my VRC430f last week, manual mentions 'Switch on' and 'Thermostat' but the unit still has 'Thermostat' and 'Modulating'

 

[UpgradeME]

Maybe someone with a new VRC430 can confirm if they have renamed it on the unit as well.

I got my VRC430f last week, manual mentions 'Switch on' and 'Thermostat' but the unit still has 'Thermostat' and 'Modulating'

I believe Vaillant manuals are originally written in German, then translated to other languages. There are a number of translation anomalies in various manuals, this may be another one!?

In the German manual, C8 options are described as "keine, Auf-schaltung, Thermostat" or according to several online translators "none, on circuit, Thermostat"

However, Aufschaltung (without the hyphon) translates to "activation" or "forward control" - I can't find a translator to get anything like "Modulating"...

The description on Pg.36 in German is:

"Aufschaltung
Der eingebaute Temperaturfühler misst die aktuelle
Raumtemperatur im Referenzraum. Dieser Wert wird
mit der Raumsolltemperatur verglichen und führt bei
einer Differenz zu einer Anpassung der Heizungsvorlauftemperatur."

which translates to:

"Forward control
The built-in temperature sensor measures the current
Room temperature in the reference room. This value is
compared with the target room temperature and results in
a difference in an adjustment of the heating supply temperature."

Here's the German manual for reference (Pg.31) if anyone speaks fluent German?

 

[smokebox]

Blimey!

How clever!

I will start evening classes
Problem is the German versions will probably vary as well, even if you could find them, though the linguistic / translation variations would hopefully be absent.
smokebox

 

[UpgradeME]

Blimey!

How clever!

I will start evening classes
Problem is the German versions will probably vary as well, even if you could find them, though the linguistic / translation variations would hopefully be absent.

There's also the nice "Simulator" here which is currently showing the v2.15 firmware options, not sure if they keep it updated...

 

[bell824]

nice simulator upgrade had that one from my tech training then lost it when i had to format my drive, cheers!
with regards to the german/english translation the germans do this at their end and when they hit our shores and we complain they say something along the lines of oh well thats how we see it and we ain't changing it,
ONE TO NOTE FOR EVERYONE NOT ALL GERMAN TO ENGLISH TRANSLATIONS ARE EXACT!
sorry had to shout it!

 

[smokebox]

A lovely simulator!
Thanks - I am playing with it now!
smokebox

 

[exocet]

I have been running a VR65 with a VR430 and external temp sensor for around 18 months.
My approach so far has been to run with a heat curve of 1.5 and then leave the heating on 24 his a day in Winter (night setback to 15 deg).

I found that with standard Rads, I had to set the Minimum Flow temp to be 39 degs else all I got was a lot of short cycling when outside temp was not too low - say 12 degs or so.

I have just fitted a Remote VR81 unit because up until now the VR 430 was mounted inside the boiler which is in the garage - not convenient if you want to adjust the temperature.

Now I have confusion over the parameters OFF, THERMOSTAT and MODULATING.

When set to THERMOSTAT, and VR81 set to 20 deg Target temp - The Room temp is actually reading 21 deg. The boiler is "OFF" - just what I would expect.

However, I just set the parameter to MODULATING and the boiler fires up with a target flow temp indicted at 39 deg (my set minimum flow temp).

Why is the boiler firing up when VR81 is reading 1 deg higher than target room temperature?

External temp is reading 16 degs - not exactly cold and using my logic - no need to fire up the boiler.

Set parameter back to THERMOSTAT and boiler behaves as I would expect.

God help anyone who buys my house when I move on....they'll never be able to work this heating system!

 

[JoeMar]

sounds like a lot of the confusions is being caused by poor translation of the user manuals.

Exocet - im sure you had your reasons but i am curious as to why you did not just wall mount the VRC430 instead of fitting a VR81?

 

[JoeMar]

Iam interested in your idea of the algorithms comparing the temperatures between zones and using that as well in the calculation. Can you expand?

All very interesting, but might get to be irritating eventually!

smokebox

hi Smokebox,

as much as i would like to tell your more im afraid i cannot. everytime is re-read the user manual (must be over 50 times now) is see things in a different way. Now that i know i cannot trust the manual i have to rethink everything i thought i knew.

 

[smokebox]

Iam interested in your idea of the algorithms comparing the temperatures between zones and using that as well in the calculation. Can you expand?

All very interesting, but might get to be irritating eventually!

smokebox

hi Smokebox,

as much as i would like to tell your more im afraid i cannot. everytime is re-read the user manual (must be over 50 times now) is see things in a different way. Now that i know i cannot trust the manual i have to rethink everything i thought i knew.

Hi Joe,
it is very early days for me, but I seem to get better , less cycling, behaviour with VRC 430 and VR81 both in "thermostat" mode, contrary to my initial thoughts.
The manual is astonishingly opaque!

Trouble is it is too warm just now, and today I am forbidden from fiddling with the boiler!

smokebox

 

[JoeMar]

Hi Joe,
it is very early days for me, but I seem to get better , less cycling, behaviour with VRC 430 and VR81 both in "thermostat" mode, contrary to my initial thoughts.
The manual is astonishingly opaque!

Trouble is it is too warm just now, and today I am forbidden from fiddling with the boiler!

smokebox

haha, i know the feeling, i installed my ufh and VR61 a few months ago and i am yet to 'turn it up' properly - still in the 'break it in' stage. running at a low temp for a few hours a day.

 

[exocet]

sounds like a lot of the confusions is being caused by poor translation of the user manuals.

Exocet - im sure you had your reasons but i am curious as to why you did not just wall mount the VRC430 instead of fitting a VR81?

Purely for aesthetics. The VR81 is about the size of a standard Room Stat, the 430 is just too big, ugly and confusing to use. In theory at least the VR81 will allow my wife to turn the temperature up, she'd never be able to drive the 430.