Yeah. Did you get the design doc from the installer? What did they say was your design temps? ie 50C at 03?
You then look at the heat curve charts and choose the most appropriate to match the design temp. But at 0.7 you’re about there i’d have thought.
Setbacks close to each other, so it doesn’t have to work so hard getting back up.
Ideally you just want the sensocomfort working in weather comp mode adjusting the flow temp to match the heat loss of the room. No other ‘controller’ making calls for heat or turning things off.
Mine ran for almost all of 20 hours straight the other day just trickling heat in.
Here’s my 5kW Arotherm Plus doing a hot water run.
This was taking my 250L Mixergy from 8% to 100% at 55C via the Mixergy plate.
Look how the warmer weather allows the heat pump to kick out 8kW for long periods.
Only when the flow got to 58C did output drop off a little.
DHW performance is something I haven’t taken too much notice off really. I plan to add some temp probes to each side of the plate (ins/outs) to see what’s going on in a bit more detail.
I’m curious how the plate exchanger compares to a standard coil that other folk have got.
45C at -3.4C with a supposed SCOP of 4.21, may be achiveable over the year who knows. That equates to a heat curve of about 0.85 at 20C internal temp. I’ve only got 2 days of data for Feb but I’m at COP of 3.75 having run at 2.43 for December and 2.7 for January. Obviously the temperature jump has helped too.
Hmmmm… My sensocomfort is in my utility room with the interface as there were supply problems winter/spring 2022 and I got a wireless unit so its near to the external temp sensor. I have heatmiser stats in
Front Room
Lounge
Kitchen
Utility (which is now off because it’s behind a toilet door which causes stupid temp fluctuations) where the HW tank and buffer and Interface are.
Landing which is all on the old pipework and rads.
They’re all plugged into the UFH Controller which then goes into the interface and the upstairs stat goes into a relay with the upstairs zone valve and the interface.
I could see if the Sensocomfort gets reception in my lounge or kitchen and programme the same pattern as I have on my heatmiser. Reading this thread I think I should probably have the downstairs all on one schedule, plus the lounge on a degree or 2 higher when needed and try to overlap the upstairs circuit with downstairs too.
I’ve noticed with one room (even the kitchen which is 45m2) on its own that sometimes the flow temp overshoots the target a bit, especially if another loop has just shut down, then it goes into Overrun > Shutdown > Time Passes > Start Heating cycle again. I suspect this isn’t as big a factor as having the heat curve set way too high. At the moment the flow temp is 33C and the target is 32C and its just the upstairs loop that’s calling for heat.
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.
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
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?
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.
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.
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.
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:
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?
and 2.7 for January. Obviously the temperature jump has helped too.
- a WEMOS and a couple of sensors from the shop and you could buy a decent meal out for 2 with the difference!
