Ecotec 418 with VRC400

[AndyAA]

We have recently had a Vaillant 418 installed with a VRC400 weather compenastor. System works really well, relativly easy set-up on VRC400, however, now the warmer weather is here there is a tendency for the heating to come on first thing in the morning when the outside temp is about 5 or 6 Deg C and the inside is about 15 (it doesn't know it's going to be a hot day!). Is there a simple way to turn the heating off and leave the hot water at the programmed times? The "OFF" function turns both off. I have set the programmed room temps to 10 Deg C on all 3 time zones for now but there must be an easier way, it's not in the manual.

 

[D_Hailsham]

Is the VRC400 installed in the boiler or on the wall?

 

[AndyAA]

The VRC400 wall mounted in the hall.

 

[simond]

I'm interested to see how D_H handles this one.

The VRC400 is a nightmare and the manual is a lesson in how to make things obtuse.

That's why we are extremely reluctant to specify Vaillant controls.

Over to you, D_H , welcome to our world.

 

[AndyAA]

One point which may be relavent is the summer/winter function on the boiler (d23, 1= winter, 0 = summer). Mine is set to 1 and I do not appear to be able to change it with the butttons on the front. Maybe this function is suppose to be changed by the VRC400 via the e-bus. I have enabled the month/year function on the VRC400 so it should know that it's summer.
Any ideas anyone?

Tony

 

[D_Hailsham]

I have enabled the month/year function on the VRC400 so it should know that it's summer.

That only changes the clock! Just because the clock now shows BST instead of GMT, it does not mean that the weather automatically changes! It can still be cold in April or warm in November.

 

[Agile]

The VRC400 knows that its summer because it will measure a warm daytime temperature outside.

You may see the comment "Thank goodness its summer" at the bottom of the display.

 

[D_Hailsham]

We have recently had a Vaillant 418 installed with a VRC400 weather compensator.

The 418 is a heat only boiler, so you must have a hot water cylinder and one or two motorized valves. This set up requires a VR65 Control Centre to integrate the boiler, VRC400 and the valves.

Do you have a VR65?

As the VRC400 is wall mounted it takes the room temperature into account as well as the outside temperature. In this case the Room Temperature Modulation setting must be set to 1 (page 37 of the manual).

If the Operation Mode is set to Set-back the heating runs continuously at the Setback (ECO) temperature (page 10 of manual). The default Setback temperature is 15C. It might be worth setting this lower, e.g 10C (page 36).

 

[AndyAA]

Yes, the system does have a VR65 and 2 single port valves. Interesting you should say about adjusting the "set-back" temp, it's not quite clear from the manual exactly what this does.
So going back to my original question, how do you disable the heating on a summers day when the morning temps are low but you are expecting a hot afternoon and wish to keep the house cool? (The hot water is still required so the "off" setting won't do)
Also, the boiler was still showing a winter setting (d23) when the outside temp was 29C and the inside about 25?

 

[D_Hailsham]

Interesting you should say about adjusting the "set-back" temp, it's not quite clear from the manual exactly what this does.

The system works with two temperatures: Comfort (e.g 21C) and Economy/Setback (15C). The Comfort temperature is used during the day and the Economy during the night or when the house is unoccupied. The time/temperature settings determine when you change from Comfort to Economy. So at 6am, say, it will change to Comfort and at 11pm, say, it will change to Economy. The heating never goes off, in the traditional sense.

Normally the VRC400 is set to Auto, so it switches between Comfort and Eco at the appropriate time. If you change the mode to Set-back, it will maintain the Eco temperature all the time. Provided the Eco temperature is low enough, the boiler will not come on.

You say that the boiler is coming on when the inside temperature is 15C and the outside is 6C. 15C is the default Eco setting, so the boiler could be running to maintain that temperature, or it could be trying to bring the house up to the Comfort temperature - depends on the time of day.

As you don't seem to mind if the temperature is only 15C, you should change the Eco/Setback temperature to say 5 or 10C and the mode to Setback. This will effectively turn the heating off all the time, unless the temperature drops below the Setback temperature.

Also, the boiler was still showing a winter setting (d23) when the outside temp was 29C and the inside about 25?

Vaillant don't explain what this setting is for. Have you tried changing it?

Have you checked that the VRC400 has Room Temperature modulation set to 1?

 

[AndyAA]

Many thanks for the info; why can't Valliant put that in the mauanl!
I have tried changing d23 on the boiler but it does not respond, it is permenantly set to winter, which it why I thought it might be set by the VRC400 via the e-bus