Thanks, I’ll start with the flow and return sensors, coupled with a csv from Heatmiser. That’ll show me what happens when I use numerous zones together.
I wonder if the app could be retrofitted to give SCOPs broken out for DHW and heating (rather than manually drilling down).
I guess you would need to bring a signal in from the 3 port valve and use that to push the data into another bucket or whatever.
I’m hoping that was sarcasm 
- a WEMOS and a couple of sensors from the shop and you could buy a decent meal out for 2 with the difference!
I’ve gone off Shelly. Too many pictures on the Facebook support site of burnt out relays.
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@Timbones and I had thrown some ideas about this previously and mentioned to @TrystanLea
We think the best option could be a CT clamp on the power to the DHW pump. Then have a wattage check on that clamp
For example, my controller based CT clamp registers no more than 2W when heating. But then when DHW kicks in, the pump goes past 10W etc.
So if <10W = heating
if > 10W = DHW
Hi All,
So having happily set my heat curve to 0.7 I was surprised to see my Target flow temp on the Interface (VWZ AI) at 60C and 42C on the Sensocomfort this morning. It was -2C at the time according to my external sensor and air inlet temp was -4.3C. Sensocomfort is following the heat curve, the Interface isn’t which is what I assume is driving the HP.
My heat demand had been stable for 2 hours and was everything open ie all rooms calling for heat. Nothing dropping in and out. I’d set overnight temps a bit lower as the previous evening I’d seen a couple of shorter runs at 100% capacity so I was wondering if lower temps might allow the system to stabilise at less than 100%. It didn’t and I guess at -3C it would be working flat out to maintain 20C anyway.
Flow temp was 38.2C and return temp 30.5C (my flow is constantly between low and high 1500 l/h so kicking out the rated 12.5kW assuming glycol in my system). About 45 minutes later flow temp had nudged up to 39C. So not too surprisingly in sub zero conditions at 100% capacity my house heats up slowly. 5 hours later its nearly at 20C everywhere.
Anyone got any thoughts on target flow on the interface being at 60C?
Next steps for me, now I’ve got a bit more data I’m going to go back to my installer and ask him about
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Switching my Heatmiser stats over to timed periods of being open rather than room stats that cut in and out and confirm that there’s nothing in my set up which would stop me using the Sensocomfort in Room Temp Mode: Expanded. This is the weather comp mode right?
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Modifying my buffer to volumiser. Probably after I’ve got my flow and return sensors hooked up.
@Zarch what % of max output does this long run equate to. The info on the Energy Integral suggests 25% is the floor for the compressor so I shouldn’t expect the Room Temp Mode to be able to trickle below 25% for very long or a have I conflated two separate topics here?
So from what I can tell at low external temperatures in Weather compensation mode the Target flow is around 60C until the Sensocmofort Temp > Desired Temp. Then the target temp drops to <30C.
I’ve never seen this during heating. The only time my flows go towards 60C is during hot water runs.
Which mode have you got the heating set to?
- Inactive = pure WC
- Active = WC with room influence
- Expanded = WC, Room influence, but also acts as on/off stat switching the heating off if room temp is exceeded
Today was on Expanded because I misread the different descriptions. However I saw 60C target temp at 2C on Inactive. Which is what I will revert to. Speaking to my installer I cleaned out my filter and my flow rate is at 1900l/h again. I suspect this may have been the cause.
My installer has checked with Vaillant and advised me to remove the temperature sensor that is in my buffer. I just pulled out the VF1 connection to the interface. Seems in line with the recommendation run without a buffer. Vaillant have just changed their advice on this apparently.
Had the odd day at COP of 4.5-5.0 in Feb, just bringing down the heat curve has got me to a COP of 3.5 for Feb. Since I’ve been looking at HW and Heating separately I’ve seen a COP between 2.3-2.9 on HW and 3.4-6.6 on Heating.
Hopefully the temp sensor removal will get me to SCOP territory of 4.0. Looks like thats where the break even point for a gas boiler will be next winter going off Cornwall Insights unit price predictions.
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My first look at “Normal” versus “Balance” for hot water
Reminder.
So in summary. Not much difference in COP?
Electric input drops in Balance mode for that 2nd half of the run, but so does the heat output, so it would take longer, for not much COP gain?
I’m targeting 55C water here. In Balance mode the water heats to 60C (sticking to DT5). but in Normal it goes to 63C and closer to DT7ish
So that plate seems to be an issue for me when comparing to folks that just have a cylinder with a coil.
I’d be keen to compare in more detail coil versus plate.
I find this interesting,
What causes this profile (the sudden drop)?
This is the beginning of the hot water cycle, when the valve switches from CH circuit to DHW circuit. The water in the cylinder’s coil (or plate heat exchange) is much colder than the water in the heating circuit, so the temperature plummets. Quite normal from what I’ve seen. Some more examples / explanations in this thread:
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Interesting. I had a similar issue with my boiler dumping a slug of cold water into the tank on startup. It completely buggered the stratification and made the water heatup even slower.
I solved it by fitting a mixing/dump valve close to the tank that forced the cold flow to circulate back through the boiler until the flow reached a minimum temperature, when it then was allowed to feed the tank.
@Zarch - do you have any Tank sensors to show what is happening there?
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The Mixergy shows the bottom of the tank (ie the cold part) is 8C at that stage.
So that probably mixes with the 27C flow/return to create that dip.
The plate heat exchange will also have cold on one side and likely cool water in the other until the diverter flips over?
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Timely post, having got my overall COP sorted I’m nagging my installer about HW. I’ve got 73C at the end of my lunch cycle today with target of 54C. Compressor ends up at 65.9% but Power remains on Max. To be honest as you’ve indicated I don’t think the settings will give you much difference in either efficency or power consumption for the difference in time to heat.
Suspect its the Conf. DHW build. pump set to 100. This is where some definitions in the manual would help! Its either a misnamed parameter or needs explaining!
After playing about with various fixed pump speeds on the DHW side, I’ve had it stuck back on Auto for the last month or so.
I get same behaviour in Auto. Am awaiting a response from my installer, who to be fair since I’ve started throwing screenshots and questions at him on email has come back with resolutions.
Any chance you were doing your legionella run at the time? Even though the documentation says it should heat to 60ºC once and then keep it at >=60ºC for an hour, it actually heats it to 70ºC… 
My installer called Vaillant about this and they confirmed that this is normal. Looks like a bug in their documentation.
70C is an overkill for Legionella
60C is sufficient, this can be reduced to 40C-50C if the tank gets a high turnover. You’ll get a higher COP by reducing your DHW max temp to 60C
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