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  1. Matthew B

    Vaillant vSmart - Any experts out there?

    Hi Teknoline. Your screenshot shows exactly what the vSmart is advertised by Vaillant as being capable of doing. Having spent more than £200 on the vSmart, I'm really not prepared just to throw it away and buy something else. I've been in contact with people who have the vSmart and it does what...
  2. Matthew B

    Vaillant vSmart - Any experts out there?

    We're in contact with our local Vaillant "Controls Champion". He's suggested various things, including turning off predictive heating (which didn't eliminate the fluctuations in room temperature once the room was up to the setpoint, so eventually we turned it back on), allowing the boiler the...
  3. Matthew B

    Vaillant VR66 wiring control centre causing heating modulation woes?

    "That's good," he says through gritted teeth! Perhaps I expressed myself badly. There are two parts to it. The boiler should adjust the burner to maintain the requested flow temperature from the vSmart, or the maximum we've allowed on the boiler settings, whichever is the lower. That's the part...
  4. Matthew B

    Vaillant VR66 wiring control centre causing heating modulation woes?

    I think if we took it right down, then the boiler would take a long time to reach the maximum we've set, but so far changing the partial load has had no effect on the flow temperature being requested by the vSmart.
  5. Matthew B

    Vaillant VR66 wiring control centre causing heating modulation woes?

    We've already turned down the partial load from the original 24 kW to 16 kW. We could try turning it down further and see what happens. I still think it's strange that the eBUS requested flow temperature on D.009 doesn't change at all when the room's near temperature. And whatever the boiler's...
  6. Matthew B

    Vaillant VR66 wiring control centre causing heating modulation woes?

    Hi, yes, that's exactly how the boiler's supposed to work, according to the Vaillant advertising. The boiler is adjusting the flame so that once it reaches the maximum flow temperature we've allowed (65°C), it holds it there until it switches off. However, what's meant to happen next is that the...
  7. Matthew B

    Vaillant VR66 wiring control centre causing heating modulation woes?

    Hi. I checked when it was on earlier today. Foolishly I didn't check D009, but D040 was 61 (and risìng) degrees and D041 we 49 degrees. D000 is set at a partial load of 16 kW. We've manually restricted the CH to 65 degrees, as we hate the radiators getting hotter than that, which also gives a...
  8. Matthew B

    Vaillant VR66 wiring control centre causing heating modulation woes?

    For two years now we've been strugging to achieve modulation of our central heating, and I'm starting to wonder whether the VR66 is the problem. Here's our setup: vSmart thermostatic controller, connected to... VR66 Wiring Control Centre with NTC sensor for hot water cylinder, connected to...
  9. Matthew B

    Vaillant VSMart boiler temperature

    I'm interested to know what limit you set. We've got it down at 40°C during the day when it just needs top-ups of heat, and then higher at night so that it doesn't take forever to warm the house first thing in the morning. It's a nuisance changing these flow temperatures manually when the vSmart...
  10. Matthew B

    Vaillant vSmart - Any experts out there?

    Another autumn, and the same problem has returned! Since October our vSmart (number 3) has been requesting silly eBus target temperatures again (often in excess of 80°C when it only has to raise the temperature by 0.2°C and the outside temperature is 10°C). We've resorted to limiting the flow...
  11. Matthew B

    Vaillant vSmart - Any experts out there?

    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...
  12. Matthew B

    Vaillant vSmart - Any experts out there?

    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...
  13. Matthew B

    Vaillant vSmart - Any experts out there?

    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...
  14. Matthew B

    Vaillant vSmart - Any experts out there?

    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...
  15. Matthew B

    Vaillant vSmart - Any experts out there?

    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...
  16. Matthew B

    Accuracy of Vaillant vSmart internet temperature

    We have a weather station in our garden, and the temperature used by the vSmart can sometimes be a couple of degrees different. I'm no expert, but I can't see that's going to make a huge difference in the general scheme of things. As it is, our heating system seems to be working just fine on the...
  17. Matthew B

    Vaillant vSmart - Any experts out there?

    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...
  18. Matthew B

    Vaillant vSmart - Any experts out there?

    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...
  19. Matthew B

    Vaillant vSmart - Any experts out there?

    No worries! The vSmart smartphone app is used to manage the vSmart's heating curve. It can be adjusted manually, or allowed to choose its own level. It then uses local weather data from the Internet to calculate the appropriate flow temperature for our house's characteristics. The vSmart has...
  20. Matthew B

    Vaillant vSmart - Any experts out there?

    Thanks. We can certainly change the CH flow setting, which will reduce the flow temperature, cause the boiler to run more and improve efficiency. It may come to that in the end. However, we've invested in the vSmart, and we'd rather have it working properly.
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