I’m not seeing any photo or attachment on your last post - maybe that got lost along the way?
Information on the Compressor Curve is patchy to say the least. There’s a paragraph in the SMO 20 Installer Manual but I don’t find it especially helpful. Since my own system doesn’t have a variable-speed compressor I don’t have the option available myself.
One of the parameters reported by myUplink is Requested Compressor Frequency, which is the result of applying the Compressor Curve to adjust the compressor speed setting based on outdoor temperature. I believe the Frequency is reported as a Percentage, i.e. 0% is ‘Off’’ and 100% is ‘Full Speed’. The first step would be to check how high that’s going when your system is running a heating cycle (rather than a DHW cycle). If it’s more than 50% there should be scope to reduce it.
My default with AMS-10-12 (which under the hood appears identical to yours also in the menu settings) is “auto”. Did you deselect auto before taking the picture?
My status:
I get cycles from 1 hour to 2 hours and off times from 1 to 2 hours in the coldest days, the number of starts includes the defrost cycles too and with the “statistics” change integration of HA it says I get max 20 starts per day
In the summer with cooling mode I get about 24 starts per day. I had to lower the lowest target flow temp to 9C and increasing the start of the compressor at 50DM, initially I was getting 60 cycles with 12-13C as lowest flow temp.
Average run time of the heat pump per day is 12h in the winter and 8h in the summer.
Last winter: peak heating production reached 88 kWh/day
This winter so far, it’s peaking at 84 kWh/day
Curve 2 offset 2 seem to be sufficient here to keep ambient temp at 21C, it occasionally drops to 20C in the coldest days during the night only which is fine
For cooling I use curve 1 offset -4 (I was told curve isn’t useful in the summer with splitter so it’s almost flat)
BT25 with heating ranges from 24 to 33 with target temp around 28 in the coldest days
My opinion is my unit is oversized (I pointed it out to the installer last year and I was told the smaller unit cannot handle my load). So my only objective to avoid its peak energy consumption of 3.8KW that seems unnecessary near the end of each cycle at 16A (it ramps up gradually and finally peaks for a few minutes with an extra kw power and >85hz frequency when BT25 is already above target), but the current limiter doesn’t work. They didn’t install the energy current meter, and I wonder if it can’t work without it.. I was told it’s only needed on three phase systems. So B1/2/3 reads 0.1.
When I deselect auto I also get the curve -3 7. I tried to tune it down to -13 7 and then BT25 rose too slowly, barely keeping up with demand. System ran continuously for hours without cycling, triggered more frequent defrost cycles, deltaT between supply and return also was reduced. GP12 (charge pump) slowed down to around 50%, didn’t reach 100% anymore. The HZ also were greatly reduced. The energy consumption was greatly reduced too.
I also wonder how the info section show the Ampere of EB101 and how the Energy log show a energy consumption if there’s no current sensor installed? Both seems underestimated in fact, maybe by 15%.
-13 7 was too relaxed but after the test I selected “auto” again because my worry is the “auto” compressor curve is smarter than the “manual curve defaults -3 7” and changes frequency in response not only to outside temperature, so I’m uncertain if it’s good idea to try again to go manual with a less relaxed setting.
I also tried blocking frequencies above 85hz keeping the compressor curve to “auto”, because I’m really after removing the last kw of electric energy consumption, but that caused GP12 charge pump speed to drop to 15% when the compressor started, I never seen GP12 droppping below 30% before. Supply temperature rose 10°C above return — (usually deltaT is in the range 5–7°C tops). So I quickly disabled the block frequencies feature. However the 15% charge pump speed happened again at the start of the next cycle and then never again, so I wonder if it was an unrelated fluke.
Does the COP and/or longevity of the heat pump increase by allowing the HZ above 85 at the peak power of the heat pump? I thought the answer is no to both… and because I don’t think I need it I thought it was worth a try, mostly to reduce the risk I hit the circuit breaker during the coldest winter days, but the fluke in the charge pump speed dropping to 15% didn’t look good. Chances it’s a bug in the firmware and nobody tested the block frequencies from 86 to 120 so I’m not inclined to try it again.
Thanks for all useful info provided by this project and forums.
I believe that with your help and the forum I now have a working knowledge of my system. I am still making small adjustments to various parameters, but I am very close to the efficiencies I was hoping for. My Kwh consumption has fallen from an average of 24Kwh/day to about 13Kwh/day.
I would like to add power usage to further refine my settings. I see NIBE have a unit EM 271. Is there a better option or can you recommend a topic to read on this forum?
The NIBE manual for the SMO S40 controller talks about the option to connect “up to three electricity meters” - but based on your first post you’ve got the SMO 20 controller which doesn’t appear to offer the same facility (unless I’ve just not found the details for that yet). So while the EM 271 says it’s specifically for the F2040 (which you have) I’m not sure it will work with your SMO 20.
I can see the appeal of having a meter which reports via your existing SMO controller and the myUplink App so I’ll do a bit more digging in the morning to check what might be possible along those lines.
An alternative would be something like SDM120M Modbus MID 45A - Shop | OpenEnergyMonitor - which could be interrogated automatically via its MODBUS interface (but then you’d need something to do that…) or just by reading the display.
Do you have a view on how often you’re going to want the meter readings recording, and whether you might add other metering (e.g. perhaps a Heat Meter) later?
I just thought that I would post an update. I have still not been able to get any information from my installer so I have contacted the manufacturer in Sweden and asked them to try and take some action.
I contacted OFGEM and found that no application has been made for the BUS Grant. No paperwork has been submitted to the local building control.
As recommended I bought several of the “fridge” digital thermometers and have been taking readings at various points on the system. They have been really useful. I have made several adjustments and the thermometers can very quickly indicate a result.
When I ordered the UFH there was a miscommunication as to what would be the heat source. To cover all possibilities they assumed that it would be a “Boiler System”. As a result they included a mixer valve for each manifold(2). My plumber assumed that it should be fitted and I didn’t know any different. I have now discovered that even with the mixer vale in the fully closed position it still allows for some mixing. This has resulted in the supply temperature drop from pre-mixer valve to post mixer valve of 5C. Wunda have sent replacement valves. My plumber will remove the mixers. At the same time he remove some of the 90 degree bends to improve the flow.
I now believe that my installer over sized my heat pump so it is still cycling at about 1 to 1½ hours. This means that the UFH pumps are running 24/7 and for much of the time are circulating increasingly cooler water while the heat pump is off. I am looking at installing a single pump in the heat pump to UFH supply line. The problem I have is that I need a way of sensing when the heat pump switches on so that it will switch on the “supply pump”. This will result in the pump running only while the heat pump is on. Anyone got any ideas?
I have also discussed replumbing the volumizer.
I have been in contact with NIBE customer care and told them about the problems with my installer. I am waiting for their response. It may be necessary for me to contract an MCS installer to come and commission my installation and generate all the necessary paperwork. Probably an expensive exercise but I may be able to get the Grant.
I used Heat Punk to calculate the “heat loss” for my house. (something else that my installer didn’t do) Thank you for suggesting the program. If you can use standard parameters it is very straightforward. Any “custom” inputs require a little more thought. Their Customer Care, both telephone and email are great.
Since I started to write this update I have had an email from NIBE UK. They said that the installer (they use his first name, James) will call me next week. They also said that all future communications on this matter must only be conducted with the installer. In other words they “wash their hands of the matter”. Since in the last 5 months he didn’t commission or complete any of the required paperwork, including the BUS Grant application, I do not have any expectations of a resolution.
Thanks again to the Forum. You have been a huge help.
Thanks for the update Mike. Sorry to hear you’ve not made any progress with your installer (and that they’ve not done anything to apply for the Grant) and that NIBE haven’t been as helpful as they might have been.
The SMO 20 controller includes provision for connecting an “External Heating Medium Pump” which can be used to supplement the Charge Pump if required. That’s referenced as “GP10” in a couple of places in the SMO 20 Installer Manual. I wonder if wiring your new pump to those terminals might give you the pump control behaviour you’re looking for - though it’s not clear from the manual exactly what control logic gets applied, and whether that can be configured. (Since it’s specifically for the Heating circuit you’d hope it wouldn’t run during DHW cycles, for example.) Temporarily connecting some sort of indicator lamp might be the best way to check when those terminals are made live, and whether that’s only when the heat pump is operating.
Hi Mike - I’ve been reading your posts with interest. Your comments about your installer and NIBE match my own experience. Your first post was a reply to a thread I started when I was attempting to work out what was wrong with my own NIBE system. Is your installer a “NIBE Pro Installer”? I’m hopefully entering the final phase of sorting out the problems with my installation (installed in Summer 2022 ). I’ve now been through the whole MCS, NICEIC then RECC complaints processes and am now awaiting the installer response from the CEDR adjudication following the RECC complaint process. When this is complete I will (hopefully) be able to have the issues rectified.
Hi Katherine. I originally selected NIBE because it is a long established company with quality equipment. Reading the nibe.co.uk website, “bio’s” of “The Team” and their “Mission Statement” (they call it something else) really made me feel that they were the Company to provide my system. It never crossed my mind that NIBE would tolerate installers that did not provide top service.
My experience seems to be slightly different from yours. My electrical installation was carried out by my “sparky” who did the complete house installation. He is "accredited and has “sign off” authority for Building Control. He really knows his profession and the regulations. My plumber is also excellent, but has had very little experience with ASHP supplying source heat for UFH. We are working together to resolve some issues that do need to be addressed with the UFH. For example, removal of the mixer valves, improving the pipe runs and installing an additional pump to provide a better flow to the UFH manifolds.
The ASHP plumbing installation is certainly neat, but the volumiser does not seem to be fulfilling the role correctly, and the supply temperature sensor was positioned on the return line. My main concern (compliant) has always been that my system was fitted and then basically abandoned. No amount of pleading and begging has persuaded the installer to arrange for commissioning, grant application submission, and the paperwork required by building control to “sign off” the house.
My approach to NIBE Homeowner Care in Sweden was passed to the UK Team. They have basically said all further communications must be carried out between myself and the installer. In other words, “we are not interested”. As I wrote in my last post they said that James (the STOR) installer will call me next week. I don’t know if he holds the exalted title of NIBE Pro Installer. I got the impression that he didn’t fully understand how the software and the system settings worked. (I may well not be right). Since he has allowed his MCS accreditation to lapse he says he uses an “umbrella” company. However, he won’t tell me the name of the company.
I am in Devon (Nr Honiton). Which part of the country are you living in? If I am totally unsuccessful next week I will probably ask you to give me some advice on the arbitration procedure.
On the positive side, I have spent hours learning the vagaries of ASHPs and UFH. My pump is way oversized for my house so I have some compromises, but at least I have the system working well enough to provide a comfortable environment. In time I am certain that I will be able to make further improvements in efficiency.
Hi David, Yes, that is a good idea. I have a DHW recirculation pump. My plumber suggested that I ask my electrician to install a method of controlling so that it wouldn’t run 24/7. My installer said that he could control it through the SMO 20. I spent months trying to get him to come and carryout that adjustment. Eventually I got so fed up that I had my electrician install a WiFi controlled switch.
I will try to find out about the “ExternalHeating Medium Pump”.
