Vaillant ecoTec 831 Plus and Nest - Flow Temperature

[mr. shr]

Have you recently had Nest installed?
I assume boiler flow temp was a lot higher with your previous setup?

 

[lloydio]

Yes, Nest was installed in the summer after I moved in - this is my first winter here so I can't comment on the previous flow rates. I think the 12V wire had an analogue Honeywell thermostat on previously.

I started looking into the problem once I realised the house wasn't heating up quickly and radiators just didn't feel hot enough.

I don't know but my feeling is that the previous 12V thermostat was varying the signal/resistance and informing the boiler of a flow rate where the Nest receiver is a simple on/off and does not vary the signal i.e. limiting the flow to 54C.

Does this make sense to anyone? Perhaps there is a way to set an override on the Vaillant boiler settings? Ideally Icezebra could get back in contact to confirm his solution.

 

[mr. shr]

From my (limited) understanding, your old thermostat would simply have worked as an on/off switch. I believe the Nest operates in the same way (i.e. on/off).

The OP had a Vaillant weather compensation device fitted initially and forgot to remove the old receiver so boiler flow temp was still being limited by that. I don't see that being your problem as you don't have one of those devices in your setup.

What is d.0 set to on your boiler?

 

[lloydio]

Thank you for your time on this.

d.0 is set to 24 which is the maximum for this boiler.

 

[mr. shr]

Isn't the maximum 30 or 31 for your boiler?

 

[lloydio]

The manual says the EcoTEC 831 plus has a heating output of 9-24kW.

 

[mr. shr]

Hmm I can't really think of anything else to suggest. Seems like you'd already covered all the things I know.
Is yours a systerm or combi?

I don't think d.5 is an adjustable setting. I think it's a read out of the flow temp the boiler is trying to achieve: if you have a smart contoller the value is received via ebus. If you have an on/off arrangement (like yours) then my understanding is the value comes from what ever the rotary dial on the boiler is set to.

 

[Harvest Fields]

It cant modulate the boiler if its on a vaillant which doesnt have open therm though. It can only switch it on or off. It wouldnt be able to control the modulation or the flow temperature. Not so smart after all hey.

Vaillant’s work on Ebus not OT so you need to use Vaillant controls to get the full benefits

 

[Ctrl-Alt-Elite]

Hi Icezebra - I have the same issue, with same Vailant thermostat being replaced by Nest V3 and 55 degree flow temps!

I cannot see the wireless receiver you're talking about - where/how exactly did you remove this?

Much appreciated 🙂

Cheers!

 

[Vee]

Remote access is available with the Internet Version of the Vsmart. Far superior to Nest.

 

[mr. shr]

Hi Icezebra - I have the same issue, with same Vailant thermostat being replaced by Nest V3 and 55 degree flow temps!

I cannot see the wireless receiver you're talking about - where/how exactly did you remove this?

Much appreciated 🙂

Cheers!

I think it's plugged into the front of the boiler?

Can I ask why you changed to the Nest system?