Homely controller installed on Samsung heat pump Gen7 R290 8KW

[jakeymd1 (Jake Dawson)]

Hi Everyone,

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).

https://emoncms.org/app/view?name=MyHeatpump&readkey=53646698bd10ba801ad47516e7e4a0bc

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.

[cognis0 (Tony Watts)]

Thanks for posting this. My Samsung Gen7 (16kw) and Homely Controller are due to be installed in April, so this is all useful info for me…

[HowardP99 (Howard Price)]

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.

[Duplicate post deleted. Moderator (RW) ]

[dmajwool (David Woolley)]

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:-

1. 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.
2. 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.
3. 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?

[jakeymd1 (Jake Dawson)]

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.

[HowardP99 (Howard Price)]

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.

[jakeymd1 (Jake Dawson)]

@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.

[Ringi]

@jakeymd1

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

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.