Hi there, new but have a few questions about my arotherm plus 7kW. I had it installed in October 2021, replacing horrible storage heaters. Generally I’m very happy with it. However Im wondering if its working as it should
I don’t use time control for the hearing. Purely on setback which is 19°C, SensoComfort control is mounted in the vestibule of my house where the balance radiator is (no thermostatic control on it)
Heat Curve is set at 1.2, I have not messed around with any settings. Just viewed them.
Typically, my unit will display actual temperature 19°C, matching the desired temperature. Then every couple of hours the heat pump will cycle on, even though measured temperature has not dropped (I’m understanding there is some algorithm from reading the manual) In milder temperatures it might come on for 10 minutes then cycle off. However in the cold weather I’ve had I’ve noticed some odd behaviour.
The heat pump will cycle on, ramp up to maximum capacity, stay on for however long it needs to hit the target flow temperature. All good. The I hear and also see on my smart meter that it is ramping back down, usually it goes off. In this case though i then see it start to come back up and continue longer. This perplexes me as it has met target flow tempersture. My desired temperature on the controller matches displayed temperature.
I have a weather compensation unit on my house too.
Also, should the compressor always go to maximum capacity? Reading the technical data it has a variable speed drive so should modulate how much power it needs. The only times that it seems to run at less than full capacity in heating mode is if outside air temperature is greater than 14°C, anything below that and it ramps up to full.
Apologies for the brain dump. I used to work designing and building HVAC units so familiar with compressors, heat cycme etc, but they were simple systems. Any insight appreciated.
1.2 was suggested by Vaillant, my system was fitted under the Warmworks Scotland schemrle. I cant remember seeing the heat loss calcs but i have all the documentation somewhere. Will look it out.
I have a 7 kW aroTHERM + ASHP with a sensoCOMFORT 720f controller. Can anyone point me to an explanation of the parameters listed in the Installation Configuration setting. What they do and what setting to use would be most welcome. I’ve gone there to change the heat curve, but that’s about it.
Also I’ve noticed that the sensoCOMFORT room temperature seems to read ‘high’. I’ve got a couple of other room thermometers (different brands) which agree closely and typically yield temperatures between 0.5 and 1 degree less than the sensoCOMFORT. Same with the radiator water temperature, only here the difference is more like 3 degrees?
I found the installion manuals and the installer write in 56 deg Supply, 48 degrees return. Now im assuming he was told by the designer to set it up as that. I don’t have the design report, but i have the survey paperwork the surveyor did, room sizes, insulation, wall thickness etc. I’ve turned m heat curve down to 1.00.
If i upload photos of what I have can anyone assist. Like it works, house is warm. I don’t think it’s faulty. Trouble is I’m an electrical engineer, with an engineers curiosity, with heat pumps i have enough knowledge to be dangerously if that makes sense.
If you look at the performance / working figure. We can see how it’s performing.
If you then turn the curve down until you’re cold, you’ll find what is tolerable.
End of the day, heat pumps work best at lower flow temps. Turning down the curve will lower the flow temps. But too low and you’ll not put enough heat into the house to match the heat being lost to the outside.
Only by upping a) the flow temp and/or b) the emitter sizes can you bridge that.
Hope that makes sense.
I wrote a giant article about heat loss, rad sizes, heat pump sizing etc.
Guys,
Since I do not have a HP monitoring system similar to OpenEnergy, I look at the PV invertor for the electrial usage graph.
Obviously, the drops in the graph below are due to the defrost cycles, but is it normal to have them every 30min ? (at outside temp around -3C) ? How often will defrost at -10, then ??
How should I know if the HP is recirculating or not it’s own cold air ? It is positioned at ~1m from a fence
(see second photo).
Thanks Tim.
it is reassuring that at “more” negative temps, it will defrost less often
Reg. The min clearance in front of the Ashp, Vaillant say min 600mm, I have 1100mm, with the path open at both ends.
Still, the green fence cover is like a sail of a boat, when the Ashp is working harder…
Thank you. Tempted to stick with the peaks and off-time in that case to keep the total daily consumption down. It’s early days and the weather’s been mild for the time of year, so will discuss with my installer.
Just new. Have the 10kw arotherm, 45l buffer tank, 300l vaillant cylinder, ufh,triple glazing and house is made of ICF nudura.
The 10kw pump is whisper quiet even ramped up to high speeds, but think it’s slightly too powerful for my needs as compressor never above 75% and more often around 40%. That said heating cycle during the day I use the quiet mode as it reduces the compressor more and still gives me what I need also I am running off growatt batteries so it consumers arrive 1.8kw max current from 11am to 4pm.
I run it at great curve 0.75 at present only that high at noticed when it went below zero 0.6 was not getting enough heat in. Flow around 37deg C today at 7degC.
Have had scop as high as 4.5 heating and around 3.3dhw, but recently heading dropped to 3.5 ish so trying to work out why, maybe just so much colder.
Tweaking settings run time etc to see if I can get anywhere near the scop 5.03 vaillant say it can do think at 35deg flow.
The minimum output (and input) depends mainly on outside temp and flow temp combination.
You can see the minimum outputs in the charts in post 1.
Look at the right hand side charts, that’s the kW output (the COP at that output is on the left)
ie, at 45 flow and 7C outside, it will go down to 1.8kW and even lower.
But I think it would take a strange set of circumstances (outside temp/flow temp) to get lower than that.
Especially as you’re bound by the minimum floor of electric required by the compressor in watts, which is around 450W.
I have a newly installed arotherm plus vwl 105/6 & VWZ MEH 97/6 hydraulic station. I don’t have an OpenEnergyMonitor setup yet but am reading all relevant data out of the device via ebusd (flow temp., return temp, flow rate, electrical power, yield power) and pipe it into Home Assistant via MQTT so I have some real-time monitoring set up (happy to share any configs if so desired). I have come across some curiosities that I need some help understanding.
Vaillant provides electrical power via ebus. Electrical power aligns very closely with my 3-phase Shelly setup that monitors heat pump electrical supply, so that’s all good.
At the same time, I can read the current yield power. It is my understanding that this is the environmental yield power, i.e. power extracted from the environment. As a matter of fact, when integrating this power over the full day I get almost exactly the same Environmental Yield Energy as the myVaillant App provides. Yesterday’s self calculated environmental yield based on the power measure was 34.4 kWh whereas Vaillant gives 35.5 kWh. As my data polling is not as granular as Vaillants internal polling and I am using a completely independent numerical integration, this is quite a good match.
Since I can also read flow rate, and flow/return temperatures I though that would enable me to calculate actual heating power, which by Vaillant’s definition would be Environmental Yield + Electrical Input (minus some system losses). Now comes the part I don’t understand: If I calculate heating power via 4186 J/kg/Kelvin * Flowrate * deltaT, I am getting almost exactly the values that Vaillant provides for the Yield power. You can see a snapshot of my measurements in the following picture:
P_yield is grabbed directly via ebus from the heat pump, P_heat is calculated on the fly as defined above. In my understanding, those two should not be equal. Remember I calculated above that the integrated yield power sums up to Vaillant’s “Environmental Yield”. Heating power must be higher since we’re also putting electrical energy in (and Vaillant, in multiple documents, explicitly states that Yield energy is not equal to heating energy.
Can anyone help me understand why the yield power would be equal to my calculated heat power?
EDIT:
What a stupid mistake & remarkable coincidence. It all comes down to forgetfulnes & unit errors (should have known as a physicist :D). I didn’t convert flow rate from kg/h to kg/s (factor 1/3600 error); also somehow the water heat capacity 4186 J/kg/Kelvin got left out of my calculation. Those two almost perfecly cancel out the COP factor at current flow/outside temperatures. I corrected this and now it makes perfect sense. Thanks for listening .
DHW cycle did not run this morning. Was scheduled for 03:00-05:00.
Space Heating setback is 16C from 21:30 last night through to 05:00 this morning.
Heating curve is 0.55
Am I correct in thinking it’s ignoring the setback because the outside temperature has dropped so low? Is that also why it failed to do the DHW cycle?
if that makes sense.
.
