Just a post to house any discussion or questions for this.
I had my heat pump installed 3 weeks ago running on Weather Compensation (Water Law for Samsung) I had ordered the Homely controller but my installer didn’t order the Modbus adaptor so the Homely only got installed last week.
My installer found that the circuit board in the outdoor unit didn’t match the one in the instructions, but a quick call to Homely and they were able to point him in the right direction.
I am currently on the Octopus Cosy tariff and while the Homely did seem to target the cheaper periods for running, it wasn’t having an impact on the flow temperature. This still seemed to be driven by Samsung WL. I also have the Homely Installer app and could see that the flow temperature wasn’t matching their “flow setpoint”. The installation instructions had been followed, so I fired off an email to Homely on Friday. I woke up in the middle of the night remembering another setting on the Samsung controller that is probably causing this. I changed the Standard Temperature setting from “Indoor” to “Water outlet” (under Indoor Zone Option) and this fixed the issue and it’s now obeying the Homely Flow Setpoint.
You can see on my monitoring, that it now boosts the flow temperature and inceases the indoor temperature (constained by your target temp and a temperature flexibility parameter) and does the DWH run during the cheap periods (4-7am, 1-4pm & 10pm - 12am).
The Homely Controller takes 2 weeks to do most of the learning about your home. Then it sets to minimise your running costs without compromising comfort.
If anyone has any questions, please feel free to fire them my way.
Hi, I am a 1-month old Newbie with a Samsung 8kW Gen7 that was installed a month ago and I am really not happy (understatement) with the Samsung controller. The thermostat’s span of operation is just ridiculously wide. Mine overshoots the set point by 2°C (apparently this is how it should operate) and then resumes heating after cooling by 1.7°C from the overshoot. It takes about 5 hours (on an day with OAT of ~5°C) for the house to cool by the 1.7°C but for the last 3 hours of this extended period there is an increasingly noticeable chill and the house has been positively cold for a couple of hours by the time it finally resumes heating. I tried using a Hive. That controlled the temperature extremely well but resulted rather too many compressor re-start cycles. So, I am about to request from my installer that they fit a Homely thermostat but don’t want to do this and then find other issues. So, my question is whether there are any drawbacks you have found from the Homely system? I am on the Octopus Agile tariff and have a solar/battery inverter with 7kW inverter capacity and 25.6kWh of storage. I also have a x210 Sunamp DHW system. I am in the NW of England in a relatively well insulated 1930s semi. Many thanks.
Hi Howard & welcome to the world of Heat Pump tinkering
As I see it the main options for using a heat pump’s room thermostat are:-
don’t use it at all - and refine the HP’s weather curves so that the pump delivers just the right amount of heat at all times.
use it as you are now - expecting it to control room temps in a narrow window while the HP is supplying more heat than is needed to maintain a steady state. You are discovering that this option isn’t meeting your needs.
use it as a 2nd layer of control that applies a conditional on/off switch - conditional on time of day and room temp.
I’m in my first winter of heating too, and what I’m working towards is
a). getting the weather curves more-or-less correct - so that the pump makes progress in raising the temperature of the house at say 0.1 degree per hour.
b). Sheduling 1C changes in the set-point of the thermostat at my Cosy off-peak tariff hours such that the room temp is likely to be above or below these set points. This acts as an on/off switch, but with the backup that if the temp is still too high or too low, heating will come on (or stay off) anyway.
I looked at the Homely, but couldn’t really see that it would provide much more functionality than this. Did I misunderstand it?
Hi @HowardP99, before I had the honely installed I used pure weather compensation. I set the thermostat to 30 (way over what it would ever get to) and dialled in the water law to maintain a decent temperature in the house with it only set to turn off between 4-7pm. It even dealt with solar gain quite well, I have lots of south facing windows and skylights so the sun heats up the house nicely when it’s shining. My heat pump is also on the south facing wall off the house, so it also seemed to reduced the flow temp when the sun was out as the outdoor unit picked up some sun too.
The Samsungs logic does seem to fall apart when it gets warmer, the compressor cycles back on after just 3 minutes, not giving a chance for the RWT to drop significantly and ends up cyling alot and using even more electricity. The compressor will switch off if the LWT gets 2 degrees above target, and switch back on when the LWT gets back to target which happens almost immediately (so the compressor turns back on).
Samsung have added some new settings to the R290 units which helps with this, (but still isn’t perfect). I think it’s FSV 106*. With the homely controller, I’m running in water outlet mode, so I use 1061 to set a larger hysterysis to reduce cycling. Ive settled on 5.0, which means it’s looking for the LWT to drop 5.0 degrees below target before switching back on.
You can also change the thermostat hysterysis in here too, but I’m not sure if you can make it smaller than the default 2 degrees.
Homely does a really good job at reducing running costs. Mine is now one of the cheapest p/kwh of heat on HPM (which is what we should all actually but targetting) at the expense of a little COP. I don’t think it’s perfect, but it’s very good. All it does is set a LWT so doesn’t resolve cycling on its own. I did speak to a guy from Homely a couple of weeks ago about whether they can try to reduce cycling and said it was something they had looked into at 1 point. I sent him a link to my heat pump monitoring and he said he’d raise the topic again internally.
It does turn my heatpump on and off quite a few times though the day (targeting the cheapest electricity) but i think this itself reduces cycling as it gives the RWT a chance to drop when off.
Homely does have some solar/battery integration, but I’m unsure how this works as I dont have any myself. With a battery and solar, it might not turn the heat pump on and off as much.
At the beginning, I had the temperature flexibility set to 3 degrees (which means it will try to keep the internal temp between the set temp and 3 degrees above set temp) I also had my set temp at 21, so it was getting up to 24 degrees at times, which is far too warm for my liking, so I’ve now set them to 20 and +1 and it’s now perfect (for me). I have it set back to 19 at night and have a TRV in our bedroom set to 19 so it never gets too warm for sleeping.
Here are some screenshots from my Tapo temperature monitors in the living room (where the homely stat is also located) and the bedroom. Both south facing. You can see it manages the temperature really well.
Just to note: I’m changing between Cosy and Agile a bit figure out which is best for me, but I think it’s fairly clear from the monitoring when I’ve been on Cosy as it targets the 3 cheaper periods alot more aggressively.
Also to note: to use Homely smart tariff optimisation, theres a £25 anually fee but this quickly pays for itself imo.
Thanks Jake. That’s really useful. I’ve sent Homely a set of questions around my system and how they would expect their thermostat to control temperatures within a suitably narrow range. The battery storage that I have will effectively mean that I don’t have a need to seek out the cheapest tariff so the system should not be constrained as to when not to run. In this way I would expect the optimum control without forced off periods. It looks like your approach of reducing the temperature flexibility to +1°C would appear to be pretty well what I am looking for. I also assume that, provided it is cold enough outside for my system that the Homely will then modulate the compressor speed to a low enough level that it then runs quasi-continuously and only cycles in milder conditions. This would be a great step forward.
@HowardP99 yeah, I suspect it will adopt the low and slow principle with enough battery and solar to cover the day’s usage.
For you, I think you could achieve the same thing by doing what I used to do, set the thermostat to 30 and dial in the weather compensation. Homely does add another feature to the Samsungs that you won’t be able to acheive without it and that’s load compensation. Samsung relies on the on/off control from the thermostat for this, instead of modulating depending on how close it is to target temp and reducing flow temps with lower set points.
Best of luck! Let me know how you get on.
P.S you can set the temperature flexibilty to zero, too, to really try dial in the room temperature.
Shame, I was hoping it would make one of the cheaper heatpumps control cycling as weĺl as the costly heatpumps from German boiler manufacturers. (Eg implement degree-minues type system and slowly increase requested LWT.)
It clear the German’s understand practical water based heating better then the aircon companies who now sell A2W heatpump, but the aircon companies make great value heatpumps with good “on paper” specs.
I have disconnected my Homely controller for last 6 days and reverted back to WL.
I wasn’t happy with the control of the heat pump with the Homely Controller. It was turning the heat pump on & off too regularly, and not working low and slow, like it should. Here are 2 screen shots, 1 from the last week before the Homely was disconnected, and 1 for the last week. Coincidentally, the mean average outdoor temp for both of these periods was 4.6 degrees.
You can see that my COP has drastically improved, even with an extremely cold snap last night.
I also simultaneously switched from Octopus Cosy to Octopus Go to make use of a cheaper overnight rate. (this coincided with changing from a PHEV to a BEV and needing to charge more than I used to) But even though I no longer have as many cheaper hours, I’m fairly sure it it costing me less money to run, and is more comfortable. I have been playing around with turning the heat pump off for a few hours at the beginning of the night, or simply reducing the WL curve by a few degrees over night from the controller home screen.
What next?
I’m still not 100% happy, I thought the Homely controller would the the answer to some of the shortcomings of the Samsung controller, but it doesn’t seem to be the answer I was looking for. So I am looking at a few of options now.
Use home assistant to set up my own method of setting the Outlet temperature based out outside temperature, time of day & inside temperature (and anything else I want to add later on). I have absolutely no experience with HA though. A guy at work said he’d be willing to help me out, but I see this is a potential ‘further down the road’ option.
Using the Samsung ‘Smart Grid Control’ functions with relays on timers to adjust the flow temp in 4 modes. a) force off operation, b) normal operation c) 1 Step-up operation (WL+between 0.5 - 5C) d) 2 Step-up operation ( WL+5C).
This seems to give me most of what I’m after in Option 1, but obviously missing the internal temperature input. This is something that I think is only available on MIM-E03EN controllers, which I have. This is really useful to get any kind of setback without using the thermostat as an on/off switch. I would have to change my WL settings so that they are set up for Mode 1 (cooler/overnight) periods and boost them to day time temps from there. This could be really useful with Cosy; Mode 1 4pm-7pm, Mode 2 overnight, Mode 3 day-time, Mode 4 during cheap periods.
Snap. I look forward to hearing how you are doing with the system. My 16kw is in about a week ago. Apart from a sticking valve that sent DHW through the heating circuit, resulting in over heating the radiators for a day while the DHW read that it had not reached target. I had noticed the energy usage first and then the temp rise. But now fixed. The unit outside is pretty quiet as it’s a warm march. I’m impressed with that. And we do like the even warmth in the house. Although I’m going to try to get it cooler at night for sleeping comfort. So far so good…
Have Homely commented on the points you raised? I would expect that they would want to address them but probably more slowly than you would like. Will be interested to hear how it goes and if you go back to Homely ( which I’m new to).
No, I haven’t heard from Homely. I did send them an email months ago, but they didn’t even have the grace to email back. I don’t foresee turning the Homely controller back on in all honesty.
For the last few months I have been on Octopus Go and have just been using the fixed weather compensation through the whole day, with DHW coming on at 00:30.
A couple of recent findings:
I got my heat pump into cooling mode a few weeks ago when we had a warm day and I was suprised how well it made the house feel cooler and more comfortable pretty quickly. Going to be playing around with this over spring to see if I can get something reliable enough running over summer. I have alot of south facing windows, so the house heats up alot when the sun is out.
DHW COP improves when the heatpump is in quiet mode, it increases the time it takes the water to heat up, but for me, the drop in temperature overnight that this causes is welcome, and is obviously cheaper. Spring-Autumn, having quiet mode on while running DHW is a no brainer. I’ve actually been running it on quiet mode for space heating too, but is more difficult to compare day to day.
I have some settings on my controller that I have discovered help with cycling in warmer weather. Some HTQ and Gen 6 users don’t have these settings. Would be interested to know if it’s a Gen7 specific thing. Do you know which you have?
I’m probably going to relocate my thermostat (currently just in an aurung cupboard) and run in thermostat mode so that I can have a controlled decrease in temperature overnight. Before autumn comes around.
Thanks for the info! I believe that I have Gen 7 as its Sam R290 16Kw? The water pump is outside the machine (ie in the house) apparently due to size of circuit but it seems to be a standard grundfos. Otherwise I don’t know much about it. The compressor is pleasingly silent and all I hear is the fan/air blown noise even beside it.
Maybe Homely are more reactive to installers? if I have issues with it I will try through them given your experience. They don’t seem to give the users much by way of any stats. I end up calculating the COP from the Samsung box on the wall. Although it gave a strange high elec use reading the other day that is at odds with my metered use. ie wrong. So I hope I don’t have a faulty one. Looking forward to comparing bills year on year swapping gas for elec and maybe using some surplus solar into the heating.
I’m interested in lowering the temp at night too. But have it set at heat during the day and not at night. It doesnt drop much. And maybe during the day. But I am letting it settle for the moment. But keeping in mind your comments on Homely.
I’ll also look into tariffs and using quiet mode night heat. Or maybe during the midday with spare solar? But the low slow point is well made. It is so complex with lots of variables, I’ll need to try them slowly so I can follow it.
