Is my Vaillant ecoTEC working properly?

[PiMike]

OK the rabbit hole just got deeper ...

 

I changed the room thermostat mode to Analogue and set the CH Part Load to 6kW which is what I estimated the property's heat loss to be. There is also a +/-5 Distance setting which affects the response time to compensate for the distance between thermostat and heat source but I left that at zero for now. The obvious differences over 2-point mode are the behaviour of flowtempdesired and disablehc. The weather is now too warm for a proper evaluation but I would say this is looking promising. What does the panel think? Should I increase the CH Part Load?

 

Mike

 

[Radian]

On 18/03/2023 at 11:02, PiMike said:

I changed the room thermostat mode to Analogue and

 

And... general note, to be properly scientific you need to adjust one parameter at a time 😉

Remind me what you expect disablehc to be - is it the changeover from DHW to space heating? I've been guessing that your DHW is timed to come on at 5AM at full load.

It looks better now although you could do with dropping flowtempdesired to 55 or 50. The only question in my mind is why modulation keeps briefly dropping to zero. You might want to plot the State number to see what the boiler is actual doing at these points.

[markocosic]

Nice work 🙂

 

 

Presumably:

 

Analogue = proportional control for room influence

 

2-point = PWM control for room influence

 

That could be code leftover from the days of boilers that fired at a fixed rate or one of a handful or rates rather than fully modulating?

 

[PiMike]

23 minutes ago, Radian said:

 

And... general note, to be properly scientific you need to adjust one parameter at a time 😉

 

 

Yes agreed, but I'm pushed for time as the weather is getting warmer which makes it harder to get a meaningful result.

 

As for disablehc, with the thermostat in 2-point mode it appears to act as a conventional on/off switch whereas in analogue mode it follows the CH programme (6am to 9am). HW is 5am to 6am. On the subject of flowtempdesired it's one of the few parameters I am unable to read on the bus. Don't know why ...

 

You might just be able to see evidence of micro-firing in the above plot, which was logged at 30 second intervals. Zooming in for the rest of that day to 10 second intervals shows it more clearly. Also the Room temperature is well above target:

 

I read elsewhere that micro-firing with the VRT392f thermostat can be eliminated by changing to return regulation, so that was today's experiment. Almost no micro-firing but back to short cycling and the modulation is stubbornly stuck at 63% ...

 

Mike

[PiMike]

On a positive note and thanks to Radian's help earlier I can now monitor my boiler from my phone with a free MQTT app.

 

Mike

 

[PiMike]

16 hours ago, Radian said:

It looks better now although you could do with dropping flowtempdesired to 55 or 50.

 

When I tried that I found the house wasn't as warm as it could be, and it's probably an experiment best carried put when the weather is cold?

 

As for my earlier comment about not being able to read flowtempdesired on the bus, I meant via MQTT, so for example this works:

 

pi@vaillant:~ $ ebusctl read -c bai flowtempdesired
10.00

pi@vaillant:~ $ ebusctl read -c bai FlowTempDesired
10.00

pi@vaillant:~ $ ebusctl read -c bai FlowTempDesired temp
10.00

 

And these work:

 

pi@vaillant:~ $ ebusctl read -c bai ModulationTempDesired
63.0

pi@vaillant:~ $ mosquitto_sub -t ebusd/bai/ModulationTempDesired/#
63.0

 

But this doesn't:

 

mosquitto_sub -t ebusd/bai/FlowTempDesired/#

 

Mike

[Radian]

3 hours ago, PiMike said:

But this doesn't:

 

mosquitto_sub -t ebusd/bai/FlowTempDesired/#

 

 

What do you get if you drop the '/#'? Or try leaving out %field in the mqtt configuration

[PiMike]

16 hours ago, Radian said:

 

What do you get if you drop the '/#'? Or try leaving out %field in the mqtt configuration

 

Dropping the /# doesn't help. Leaving out the %field doesn't help either and stops the MQTT client on my phone receiving updates.

 

Mike

[PiMike]

OK I think I'm going to drop the boiler tweaking for now as it's raising more questions than I can answer at the moment. Here are two plots from consecutive mornings, one with the thermostat in conventional (2-point) mode and the other in analogue mode (and return regulation). I can't see too much difference between them. The modulation is 100% (18kW) for HW. For CH the 2-point control looks to be better behaved.

 

Thanks for all the input!

 

Mike

 

 

 

[Lofty718]

@PiMike

Edited March 23, 2023 by JoeyF
-

[Lofty718]

I am going through the same right now fiddling with my heating system

 

But mines much more complicated it's an ecotec 630 with one external pump for PDHW + rads and another for UFH

 

controlled by sensocomort vrc720f and vr71 wiring centre. There are many different parameters you can control, have you gone into the installer settings on the boiler, where you can adjust pump speed etc

 

 

To get the most out of your system make sure radiators are balanced and the correct pump speed is set. My system is running on weather compensation and the boiler runs at 42c when it's 0c outside, it's fully controlled by the outdoor weather sensor with no room influence and I can run my system at 3 different flow temperaures at once, you should add the weather sensor to your setup too.

 

How do you fit an ebus monitor to the boiler? I'm very interested as it costs over 200 quid to get the valliant add on to allow monitoring from the phone, and I do not want to pay that

Edited March 23, 2023 by JoeyF

[PiMike]

Hi Joey, thanks for your input. There are so many parameters to play with! I have a 3 speed pump which is currently on 2 and seems to work OK there. As for weather compensation, I have only just fitted my current Vaillant room thermostat and need to understand it before moving on. There is a blog somewhere on problems with Vaillant weather controls causing micro-firing. I'll post a link when I find it.

 

My adapter follows the ebuzzz design. I bought the PCB and components from China and built it up myself. It cost £20 and works perfectly with my Raspberry Pi. I wrote a python script to capture the data every 10 seconds. That was the easy part for me. Understanding how the boiler is supposed to work is a different matter!

 

Mike

[Radian]

On 22/03/2023 at 10:46, PiMike said:

 

Dropping the /# doesn't help. Leaving out the %field doesn't help either and stops the MQTT client on my phone receiving updates.

 

Mike

 

Try specifying the temp field...

mosquitto_sub -t ebusd/bai/FlowTempDesired/temp

 

[Lofty718]

See this chart that shows efficiency drops from boiler cycling, you do not lose much efficiency unless your boiler is cycling a lot in a short space of time. vaillants have anticycling mode to boost efficiency

 

https://www.heatgeek.com/what-is-boiler-modulation/

 

chart came from heatgeek, read all the articles on here there is some great info

 

Make sure your pump is set at the right speed and you have the optimal delta t across the system, then add weather comp if you want an extra 5-10% effciency and more comfort.

 

 

 

 

 

 

Edited March 23, 2023 by JoeyF

[PiMike]

Thanks that's useful.

 

Here's a link to the ebus adapter I built:

 

https://fromeijn.nl/

 

And here's the blog that discusses Vaillant micro firing with weather compensation:

 

http://vaillantcyclingproblem.blogspot.com/p/problem.html?m=1

 

Mike

[PiMike]

6 hours ago, Radian said:

 

Try specifying the temp field...

mosquitto_sub -t ebusd/bai/FlowTempDesired/temp

 

I've tried all possible variations of the syntax and none worked. Now just to spite me the ones that previously worked don't either. ☹️

 

Mike

Edited March 23, 2023 by PiMike

[Radian]

21 minutes ago, PiMike said:

I've tried all possible variations of the syntax and none worked. Now just to spite me the ones that previously worked don't either. ☹️

 

Mike

I really don't know how you've arranged things. If you're subscribing to MQTT topics then you either have to issue periodic 'gets' or issue ebusctrl commands or edit the definition file for the boiler to get ebusd to regularly poll the parameters for you.

I debugged my setup using a windows desktop program called MQTTspy which unfortunately is no longer maintained but works well enough to visualiese the traffic.

[PiMike]

8 hours ago, Radian said:

I really don't know how you've arranged things. If you're subscribing to MQTT topics then you either have to issue periodic 'gets' or issue ebusctrl commands or edit the definition file for the boiler to get ebusd to regularly poll the parameters for you.

I debugged my setup using a windows desktop program called MQTTspy which unfortunately is no longer maintained but works well enough to visualiese the traffic.

OK thanks. Can you advise on how to edit the boiler file to achieve this please? I just want a continuous monitor of parameters on my phone without sending commands.

 

Mike

Edited March 24, 2023 by PiMike

[Radian]

4 hours ago, PiMike said:

OK thanks. Can you advise on how to edit the boiler file to achieve this please? I just want a continuous monitor of parameters on my phone without sending commands.

 

Mike

 

You have to copy the file detected in a scan to a local directory e.g.

 

/home/pi/ebusd-configuration/ebusd-2.1.x/en/vaillant/bai.308523.inc

 

and point to it in the EBUSD_OPTS e.g.

 

--configpath=/home/pi/ebusd-configuration/ebusd-2.1.x/en

 

Then change any line in the configuration file that starts with  r; to r1; to get mqtt to send the data every 10s. It's a fixed poll time unfortunately. If you want it faster then you have to poll it yourself.

 

[PiMike]

1 hour ago, Radian said:

 

You have to copy the file detected in a scan to a local directory e.g.

 

/home/pi/ebusd-configuration/ebusd-2.1.x/en/vaillant/bai.308523.inc

 

and point to it in the EBUSD_OPTS e.g.

 

--configpath=/home/pi/ebusd-configuration/ebusd-2.1.x/en

 

Then change any line in the configuration file that starts with  r; to r1; to get mqtt to send the data every 10s. It's a fixed poll time unfortunately. If you want it faster then you have to poll it yourself.

 

Thank you! That will do what I need. 10s is perfect.

 

Mike 😀👍

[PiMike]

On 23/03/2023 at 17:13, JoeyF said:

See this chart that shows efficiency drops from boiler cycling, you do not lose much efficiency unless your boiler is cycling a lot in a short space of time. vaillants have anticycling mode to boost efficiency

 

https://www.heatgeek.com/what-is-boiler-modulation/

 

chart came from heatgeek, read all the articles on here there is some great info

 

I read the article, it's very informative. Then I went back to a plot I made earlier this month when the weather was colder and realised it follows their logic.

 

This is with the room thermostat in conventional (on/off) mode. The boiler starts up at 100% modulation (18kW) for hot water then 66% for the start of the CH long burn. Once the flow temperature reaches the target of 65C the modulation drops to 30% but because my boiler can't go below 5kW it starts the short cycles as the room temperature approaches the target of 18C.

 

Mike

 

[Lofty718]

Read the whole consumer advice section on Heat Geek it is very informative

 

https://www.heatgeek.com/weather-compensation-or-load-compensation/

 

Also if you use facebook I am part of an interesting group on there where we all discuss stuff like this, but main focus is low temperature heating. Group name 'Heating system design'

 

In the UK we have an issue of installers oversizing boilers, mine put in a 30kw when I could of had 15kw and even that would be too much, the consequence of that is that my boiler cannot modulate below 6kw.

Edited March 25, 2023 by JoeyF

[PiMike]

On 25/03/2023 at 00:15, JoeyF said:

Read the whole consumer advice section on Heat Geek it is very informative

 

https://www.heatgeek.com/weather-compensation-or-load-compensation/

 

Also if you use facebook I am part of an interesting group on there where we all discuss stuff like this, but main focus is low temperature heating. Group name 'Heating system design'

 

In the UK we have an issue of installers oversizing boilers, mine put in a 30kw when I could of had 15kw and even that would be too much, the consequence of that is that my boiler cannot modulate below 6kw.

 

I don't use social media, life is so busy I can't find the time. I'm more than happy with the fantastic help available on forums like this. When my boiler was installed in 2009 I didn't know enough to ask what rating it was. I assumed the installer knew what he was doing ...

 

This puzzles me. I set the CH part load to 8kW, assuming that this is the maximum the boiler would use, but in the graph above it's running at nearer 12kW (66%) at the start of the CH programme.

 

Mike

[Lofty718]

The boiler will fire up on full power for the first minute, that's just how they are designed. Vaillants anyway, I'm not sure about others

[PiMike]

6 hours ago, JoeyF said:

The boiler will fire up on full power for the first minute, that's just how they are designed. Vaillants anyway, I'm not sure about others

Fair enough, but full power would be 100% not 66% ...

 

Mike