VAILLANT 831 not reaching temp

[Coldone]

Hi all
First post, please help
Moved into a house in the summer
Has a 2011 Vaillant eco tec plus 831
Had heating on for a week or two and can’t get the boiler to go above 50 ish degrees on heating
Flow temp on the dial is set to 70
But when it gets to 50 it knocks off
Checked the d.0 etc and no joy
I’m baffled and the wife’s whinging it’s cold!!!!

 

[CBW]

What thermostat do you have installed?

 

[Coldone]

Hive

 

[Coldone]

Just to add
If I put the boiler in chimney sweep mode it goes right up to 80 odd no problem

 

[CBW]

Can you check D5?

 

[Coldone]

43

 

[Johntheo5]

Also d.71 and d.40&d.41 while running up to 50C.

 

[Coldone]

D40 = 53
D41= 43

There’s is no d70

 

[Coldone]

So there is no d.71

 

[CBW]

43

That’s probably why then. Get into D71, by accessing the installer 2nd level and change it. See attached, seems odd though, as you said it’s 70 on the front?

 

[CBW]

So there is no d.71

There is, it’s via a 2nd (hidden) menu.

 

[Coldone]

D71 is 70

 

[CBW]

Can you post a photo of the front of the boiler? Is there still, or was there a previous Vaillant control?

 

[CBW]

I can’t see how d5 is 43 and d71 is 70 unless ebus controls fitted.

 

[Coldone]

Yes there must have been a Vaillant control at control at some point as the receiver was plugged into the front
I have tried with it in and with it not in and no difference