Vaillant vSmart - Any experts out there?

[MartinSeeker]

Matthew you need to allow two weeks for thermostat to learn. After learning preriod it should work as a charm. Your posts are from a month ago so probably you have already figured this out.

 

[Matthew B]

Thanks for your reply. We'd had the vSmart for about 9 months, but the problems had become really apparent with the onset of the colder weather.
Eventually Vaillant sent a "controls champion" to us to try some things. We gave it a further fortnight, at the end of which it was requesting a flow temperature of 90℃. So Vaillant then replaced the whole system under warranty: thermostat, communication centre and wiring control centre. After 4 days it switched to advanced mode, and it now calls for flow temperatures in the 35-55℃ range, and it's maintaining our set temperature within 0.1℃, so it looks like the first system was simply faulty. We're really happy now.

 

[Matthew B]

Just to round off this discussion, I thought it might be worth posting a couple of screenshots, showing how our heating system performed before and after replacement of the original vSmart system by our Vaillant "Controls Champion" Andy - our new hero, as it turns out!
The first (which I posted with my original post) shows how the boiler was working frantically to get the radiators really hot, resulting in unpleasant amounts of heat coming from them, and the temperature overshooting the set point by nearly a degree, with fluctuations in the temperature at the thermostat.

The second shows how the system is working now with the replacement vSmart. The boiler comes on more frequently, but maintains a much lower flow temperature, meaning the radiators only provide little more than background heat to keep the temperature almost perfectly constant throughout the day. This is exactly why we bought the vSmart, and it's great to see it finally working as it should. Hopefully it will help the boiler run more efficiently and last much longer (probably until the government tells us we all have to rip out our gas-fired heating and go electric...).

 

[Peter24]

Hi Mathew i am having similar issues as you had, when vsmart reaches desired temp or approaching temp D9 (52C) is not reducing flow temperature so when the temperature has reach my boiler just turns off ,when room temp has decreased the boiler will turn back on with D9 with a lower number say 35c and so the micro firing starts, my question is when your vsmart room temp is close to desired is D9 reduce? I have spoken to Villaint on number of times but TBH they have not been much help other to say we have a well insulated house.

 

[Harry Bloomfield]

I have spoken to Villaint on number of times but TBH they have not been much help other to say we have a well insulated house.

Vaillant UK don't seem to know very much about the technical aspects of the systems they sell.

 

[Matthew B]

Hi Peter.
Since our vSmart was exchanged, it's been matching the setpoint temperature well, overshooting by just 0.2 or 0.3 degrees at most. However, we haven't seen it reduce the flow temperature while the boiler's actually running, which is what we'd expected to happen.
However, now the radiators are just providing gentle background heat, we're not always aware when it's running, so it's harder to monitor exactly what happens with the flow temperature from the start to the finish of each firing cycle. All we know is that the boiler runs more often at lower power, which for us is the main thing.
I'm not convinced many people at Vaillant understand what the vSmart is meant to do, despite every email from the company telling customers to ask the engineers about it...

 

[Peter24]

Hi Matthew I am beginning to think this is a bit like VW compliance product, If you get the change to look at D9 throughout the day and see if this setting is getting lower as the setpoint is near would be be helpful ? also what firmware version is on you old new ? i am running 11 and 21 on the gateway. sorry to badger you but not able to get answers like this from Villant support

The sales buff says
What does Room compensation mean?
This means the controls look first at the user set room temperature, then the controls look at the actual room temperature. The controls will then increase or decrease the boiler flow temperature in the most efficient way possible to reach the desired set point. As the set point is being reached the flow temperature to the radiators will reduce as the boiler modulates down to match the heat loss of the property while still maintaining the set point.

But this is not the case for me it just reached setpoint then D9 is set to 0 boiler off might as well kept my old thermostat and save £155 Its like the heatcurve is only taken inputs from outside temperature not internal. I purchased this for this feature.

For now i have had to set the heating knob on the front to about 48C , I have played around with the heating curve and also left it to autoset its about 1/1.2 any lower the house in warmer times the flow temp is too low and the boiler just goes into antycycle ( also played around with the timing for this too ) currently set to 30

 

[Harry Bloomfield]

This means the controls look first at the user set room temperature, then the controls look at the actual room temperature. The controls will then increase or decrease the boiler flow temperature in the most efficient way possible to reach the desired set point. As the set point is being reached the flow temperature to the radiators will reduce as the boiler modulates down to match the heat loss of the property while still maintaining the set point.

That part seems to work absolutely fine on my system. As it nears the set temperature it ramps down very gradually so it doesn't over shoot, then holds the set temperature very accurately - within just a fraction of a degree.

My only two concerns (which I have given up trying to solve), is that the boiler seems to do a random purge cycle without actually igniting or needing to produce any heat. Then during the wee hours, when room temperature is higher than the desired - I often hear the pump start and the pipes ticking, as if the boiler is producing some heat, however - feeling the radiators they remain cold.

 

[Matthew B]

Hi Peter.
We've studied the D9 temperature on our boiler, and it doesn't change while the boiler is running. It just changes to 0, like yours, and enters anticycling mode. When it next comes on it's generally at a lower flow temperature to maintain the room temperature, or higher if we've requested an increase in room temperature. It automatically changed the heating curve from 2.6 initially to 1, and it's now taken itself down to 0.6. (We have a well-insulated house, so it copes well at that level.) We're not sure that the lower heating curve value has been reflected in lower flow temperatures.
We've left the boiler at all the default settings (including partial load set to "Auto"). We have the default anticycling time (20 minutes?), but we don't know what the optimum setting is when a vSmart is fitted.
We have the same firmware as you: version 11 for the thermostat and version 21 for the gateway.

Harry,
We're interested to read that your system is modulating properly for "room compensation", and would be really interested to know what settings you have on your boiler to achieve that, as the vSmart documentation says nothing about boiler settings. It would be really helpful if they could publish recommended settings.
Regarding the pump running at night, could it be related to D.018 (Pump operating mode)? In Eco mode, "internal pump is switched on every 25 minutes for 5 minutes once the overrun time has elapsed". That's in the installation and maintenance instructions.

Like both of you, we just want our system to run as efficiently as it possibly can, but we're not sure what the optimum settings are to achieve that.

 

[ScottishGasMan]

The VSmart is inherantly a complicated system, in that it uses both room temperature and external temperature to decide on the flow temperature it wants.

Most weather compensating systems use a heat curve which will only be affected by the outside temp, ie when its 0 degrees outside, the flow will always aim for 60, and when its 10 outside, the flow will always aim for 40.

Room modulation stats, do the same, but only using the internal temperature, so if the difference between the requested room temp and actual is close, the boiler will fire at a low rate, and when its quite a bit away then it will fire at a higher rate.

There is the Flow Target temperature, And there is also the Power Output of the boiler. The VSmart uses the Internal and external temperature to alter both the desired flow temp AND the power that it will use to hit that temp.

For example, turn your vsmart up 2 or 3 degress over the current temperature and it will quickly do some calculations and your boiler will show you the ebus requested temperature, then turn the stat up another 5 degrees above that, and you will see the desired flow temp change, even though the external temp has not altered.

You have to remember that while a modulating boiler is more efficient than an on and off system, there are still limits to how effieicent it can be, they can only modulate the power down so far, so eventually the boiler will need to turn off to allow some heat to dissipate from the property before it will fire back up, it could run the radiators constantly at 25 degrees flow temp almost all the time, but thats not neccesarily more efficent than running at 40 and occasionally shutting off for a while.

 

[Matthew B]

Yes, our vSmart does set a sensible flow temperature when the boiler fires up, and the boiler then adjusts the power output to maintain that flow temperature throughout each firing cycle.

However, what ours isn't doing - like Peter's - is to adjust the flow temperature during the course of the firing cycle. Vaillant's advertising suggests the vSmart will select a higher flow temperature (let's say 50°C) when the room is some way below the target room temperature, and then reduce the flow temperature (let's say to 35°C) when the room temperature gets near the target, before possibly switching off when the target is reached (depending on heat loss from the room). With our system, whatever flow temperature is selected when the boiler first fires up is maintained until it switches off. The requested flow temperature only changes the next time the boiler fires.

So, yes, I'm sure it's working quite efficiently. My issue is that it's not doing what the bumph says it should do.

 

[Matthew B]

As an experiment, we waited for the boiler to fire up and then increased the requested room temperature by 5°C to see what would happen. This actually increased the requested flow temperature considerably. When we turned the temperature back down again, the boiler turned off.
This shows the vSmart is capable of changing the requested flow temperature while the boiler's running.

 

[AndriiPin]

My greetings from far away (It is Ukraine!)

As an experiment, we waited for the boiler to fire up and then increased the requested room temperature by 5°C to see what would happen. This actually increased the requested flow temperature considerably. When we turned the temperature back down again, the boiler turned off.
This shows the vSmart is capable of changing the requested flow temperature while the boiler's running.

I have a question to Matthew B, since you seem to have been experienced in the vSmart matter.

My problem looks very similar to that of yours. So, let's start with the equipment, hardware, and software and then work up to the problem.
In July last year, the Vaillant Officials installed Vaillant ecoTEC pro VUW INT 286 /5 -3-H operated by the eRelax. The smart system is supposed to modulate the boiler's power according to the temperature outside.
Just as in your case, I started to question the "smart" feature of my system when cold weather came. Whatever the outside temperature was the boiler's flow temperature always reached up the maximum. The official service advised me to manually set the heating curve at 1.5. I did so and the boiler stopped operating at a maximum flow temperature. It began to analyze the outside temperature to adjust the flow temperature in order to maintain the desired inside temperature. However, somehow I feel it doesn't work as it should, since setting the heat curve manually doesn't make any sense! What part does the "smart" system play in it?

The officials also told me that 1.5 heat curve is the most efficient setting for my region, but I can play with it for the sake of experiment. So, here is the most important thing. When I let the eRelax automatically regulate the heat curve in the app, it snaps back to its misbehavior. Whatever the heat curve the "smart" system sets the boiler's flow temperature is always at the maximum level! Here I come to the question:

Matthew B., is the heat curve set in your system or does it vary?
Setting the heat curve doesn't make sense, because the heat loss depends not only on the outside temperature but also on the desired temperature inside the house.

My guess is that the "smart" system should adjust the heat curve itself to ensure the most efficient gas consumption!

 

[Harry Bloomfield]

Obviously it’s not that Smart.

I think the 'smart' is that it trims the boilers output to the requirement for heat - it knows the room temp, it has an idea of heat loss, so it knows at what level to run the boiler so it just hits the need for heat without over run..

 

[Matthew B]

My greetings from far away (It is Ukraine!)



I have a question to Matthew B, since you seem to have been experienced in the vSmart matter.

My problem looks very similar to that of yours. So, let's start with the equipment, hardware, and software and then work up to the problem.
In July last year, the Vaillant Officials installed Vaillant ecoTEC pro VUW INT 286 /5 -3-H operated by the eRelax. The smart system is supposed to modulate the boiler's power according to the temperature outside.
Just as in your case, I started to question the "smart" feature of my system when cold weather came. Whatever the outside temperature was the boiler's flow temperature always reached up the maximum. The official service advised me to manually set the heating curve at 1.5. I did so and the boiler stopped operating at a maximum flow temperature. It began to analyze the outside temperature to adjust the flow temperature in order to maintain the desired inside temperature. However, somehow I feel it doesn't work as it should, since setting the heat curve manually doesn't make any sense! What part does the "smart" system play in it?

The officials also told me that 1.5 heat curve is the most efficient setting for my region, but I can play with it for the sake of experiment. So, here is the most important thing. When I let the eRelax automatically regulate the heat curve in the app, it snaps back to its misbehavior. Whatever the heat curve the "smart" system sets the boiler's flow temperature is always at the maximum level! Here I come to the question:

Matthew B., is the heat curve set in your system or does it vary?
Setting the heat curve doesn't make sense, because the heat loss depends not only on the outside temperature but also on the desired temperature inside the house.

My guess is that the "smart" system should adjust the heat curve itself to ensure the most efficient gas consumption!

Your problem sounds similar to what we experienced until Vaillant replaced the whole vSmart kit (i.e. the wiring control centre, communication unit and room thermostat) under warranty at the end of 2019.

Until that point, the heating curve made little difference to the flow temperature being requested over the eBus (D.009). However, since the kit was exchanged under warranty, our vSmart has been behaving as expected, meaning that if there's a big room temperature rise requested (say +2°C when the heating comes on in the morning) the flow temperature is higher (often about 55°C), but if it's just being asked to maintain the room temperature the flow temperature is nearer 41°C.

When our replacement vSmart was installed the heating curve started off at 2.6. We've resisted the temptation to fiddle with it, and it's automatically reduced itself down to 1 and now 0.6.

Vaillant's technical people were at a loss to know why our system wasn't behaving properly. However, it seems to have been a hardware problem, as it now works well.