hi mike

so on the samsung side B22 is the switched 230v live input for heating. B21 if you want to put the system in cooling mode, remember it can cool your house as well if you have cooling capable emitters. Thermostat2 inputs are for a second zone, not needed I expect in your setup.

using these requires you to also change the FSV settings to use the  external thermostat input (I can't remember which one, RTFM!) instead of the controller . probably the way you have it now it'll be using the thermostat in the wired controller to control your heating and ignore B22.

samsung doesn't have any scheduling for heating, you have to source that externally.

be wary that using the system in external thermostat mode means that  , if the external stat is too keen to switch on/off over short intervals, you can get very inefficient behaviour out of the ASHP. This has been the case with some "simple on/off" boiler type stats and is the reason why some people have historically said "my ASHP costs me a fortune" and so has led some ASHP heating engineers to have a blanket "no external thermostats allowed" statement. However , if you use the external stat input with something more intelligent driving it (as I have) then it can be kept efficient. 

But: your heating controller is an opentherm controller (google your thermostat) . The L and N are purely a 230v AC power supply to it. The other two wires are DC low voltage out, signal according to opentherm specs. Those will have gone to an opentherm input on your previous boiler. There is no way to connect it directly to inputs on the samsung. where / what was it connected in your ashp system prior to the changes that you've just done?

hopefully if your stat is OT, its going to be a bit cleverer about avoiding the short on/off switching issue, but there still has to be something between it and an ASHP system such as yours , because they don't take OT inputs. So, some DIY electronics may be required (to convert OT to a 230v switched live), if whatever was there before isn't re-usable. There is some pre-made stuff out there if you google ( https://diyless.com/product/arduino-opentherm-gateway), no experience of it here.

I'm intentionally not commenting on the 24/7 point, this has been done to death 1000's of times.

The other way to do this would be to look at using a Homely controller instead. I've never used one , there is debate on here about them but it should, according to the specs, give you what you want, in a canned solution. one member on here was about to get one.

ta

Ian

@iancalderbank Hi Ian, Thanks very much for your reply, which has been very helpful. My thermostat was installed at the time of the original installation, so it was wired to the Samsung control kit, before being disconnected during the recent changes. I have found a helpful diagram in the ESRTP4RF+ instructions (see attached). The black wire (Terminal 1) is apparently a linked live feed - although the thermostat has OpenTherm capabilities (something I had never heard of), there are no connections to Terminals 5 and 6. I believe I need to connect the Brown and Black wires to B20 and the grey wire to B22. The engineers had to remove the thermostat wiring as they have connected B20 to B22 in order to mimic a thermostat permanently calling for heat. Without an external thermostat, it appears that there is no other way to utilise weather compensation (Water Law) on the Samsung. They then set FSV 2091 and 2092 to 'Use(Signal ON/OFF) or WL Interlink OFF(Water Pump3)'. So it is now set up for using Water Law.

The wired controller was moved from the porch to the kitchen/hall to make use of it's superior thermostat control. However, as far as I can tell, when set to use Water Law, room temperature as measured by the wired controller has no influence on the flow temperature, compressor speed or delta T. This seems like a missed opportunity. I see that you and others are trying to create a more sophisticated controller using modbus with variable amounts of success. I will be interested to see how you get on. Although I have done quite a bit of coding in VB, VBA and SQL, I have to confess I am completely lost when I read the instructions on Open Energy Monitor or the threads about modbus and home assistant

on this forum. Homely sounds very interesting, but I am waiting for more feedback about it. Thanks again, Mike

Posted by: @mike-h

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@iancalderbank Hi Ian, Thanks very much for your reply, which has been very helpful. My thermostat was installed at the time of the original installation, so it was wired to the Samsung control kit, before being disconnected during the recent changes. I have found a helpful diagram in the ESRTP4RF+ instructions (see attached). The black wire (Terminal 1) is apparently a linked live feed - although the thermostat has OpenTherm capabilities (something I had never heard of), there are no connections to Terminals 5 and 6. I believe I need to connect the Brown and Black wires to B20 and the grey wire to B22. The engineers had to remove the thermostat wiring as they have connected B20 to B22 in order to mimic a thermostat permanently calling for heat. Without an external thermostat, it appears that there is no other way to utilise weather compensation (Water Law) on the Samsung. They then set FSV 2091 and 2092 to 'Use(Signal ON/OFF) or WL Interlink OFF(Water Pump3)'. So it is now set up for using Water Law.

The wired controller was moved from the porch to the kitchen/hall to make use of it's superior thermostat control. However, as far as I can tell, when set to use Water Law, room temperature as measured by the wired controller has no influence on the flow temperature, compressor speed or delta T. This seems like a missed opportunity. I see that you and others are trying to create a more sophisticated controller using modbus with variable amounts of success. I will be interested to see how you get on. Although I have done quite a bit of coding in VB, VBA and SQL, I have to confess I am completely lost when I read the instructions on Open Energy Monitor or the threads about modbus and home assistant

-- Attachment is not available --

on this forum. Homely sounds very interesting, but I am waiting for more feedback about it. Thanks again, Mike

in the mode you have been setup with, the samsung stats "superior thermostat control" may not be being used. 

see most of the settings on page 6 of here

MIDSUMMERWHOLESALE.CO.UK "https://midsummerwholesale.co.uk/pdfs/pre-plumbed-schematic.pdf"

what is indoor zone option set to? it'll be either "indoor" or "Water outlet".

if set to "indoor" - your indoor controller is the stat. B22 does nothing (it was pointless them wiring B20 to B22).

If set to "Water outlet", your third party stat is the stat, and has to be looped through B22, because B22 calls for heat. If B20 is wired directly to B22, then the system is always calling for heat, there is no stat.

seems your ESPRTP stat also does indeed also do simple switched live  on/off, I didn't spot that, so you could just loop B22 through it as you said, then could then switch the system on/off from your device , and thus add timing if you want it. In that case, be careful about looking at what hysteresis it does. you don't want on/off signalling every few mins when its near target temp.

you can still have water law, whether you set the wired remote controller itself to be the stat - see above regarding "indoor zone option" - or use a 3rd party stat. the issue with 3rd party stats is avoiding too short cycle times hunting around a target temperature with very small hysteresis, leading to inefficient running. not water law.

doesn't matter whether WL is in use or not: attributes like actual flowT, compressor speed and DT are determined by the overall system, you can't set them directly. The only thing that you can (attempt to) set directly is "target flowT" or the "WL max/min points" (depending on vendor)  - which then have the potential to give a higher degree of control over the system- these are the subject of some of the experiments you refer to.

@iancalderbank my indoor zone option setting for standard temperature is ‘Indoor’. However, because FSV 2091 is set to option 4, there is no option to set desired room temperature, just the option to set the water Law offset.

Posted by: @mike-h

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If I want to use room temperature, I have to change FSV 2091 to the option to not use the external thermosta. In that setting, I can set the desired room temperature but it won’t be using weather compensation. I am not sure, from an efficiency point of view which setting is best. The engineers were obviously trying to get the best of both worlds, but I don’t think that is possible without something like Homely. 

 there is a definitely a setting combination that gives you the samsung controller as the room temp stat, with WL. I am fairly sure its 2091 = 0 (because this is the default, and the ssytem by default works off the wired controller), but I don't run in this mode so I could be wrong. ask other samsung users on here for their settings if you want other data.

efficiency, you want both. WL, and a room temp stat to control when to run and when not to. you can have both with the standard controller.

what you cant have with that controller is timed heating. which one do you want to solve the most?

@iancalderbank Yes the setting to use the wired controller as the room stat is FSV 2091 = 0 (Not use external stat); FSV 2092 =0; Indoor Zone Option --> Standard Temperature = Indoor. The screen then allows you to adjust desired room temperature. I assumed that this setting doesn't use weather compensation, but I may have been mistaken.

Pure weather compensation (Water Law) is done by selecting FSV 2091 (&2092) = 1-4. This only works if an external thermostat is wired to B22 (or B20 is wired to B22 to simulate an external stat as in my case). The screen allows you to alter the offset on the Water Law from -5 to +5. Let us assume that you choose sensible settings for the upper and lower limits of the WL curve and ignore the varying influence of solar gain. If you then set the external thermostat to 30 deg C, the ASHP will run all the time and keep the house at a roughly constant temperature of say 20 deg C. As the outside temperature drops, the flow temperature increases and vice versa.

If you then change to using the wired controller as the room thermostat (FSV 2091(&2092) = 0), what happens if you set the room stat to 25 or 30 deg C? Does it ramp up the flow temperature to achieve the higher room temperature or just follow the WL curve? If it is the latter, I cannot understand why the engineers went to the trouble of wiring B20 to B22.

Posted by: @mike-h

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If you then change to using the wired controller as the room thermostat (FSV 2091(&2092) = 0), what happens if you set the room stat to 25 or 30 deg C? Does it ramp up the flow temperature to achieve the higher room temperature or just follow the WL curve? If it is the latter, I cannot understand why the engineers went to the trouble of wiring B20 to B22.

In that situation, the flow temp follows the WL curve. The target room temp affects how long the system stays on, until that room temp is achieved. Not the flow temp.

I don't know why your engineers did what they did either. If you are using the wired controller as the room stat with 2091=0, you don't need B20 wired to B22, it does nothing. If you are using an external stat, you don't wire B20 to B22 either, you wire B20 to "external stat in" and "external stat out" to B22.

FYI some of the tinkering that people are trying to do is about trying to give systems a "boost mode" where LWT is temporarily raised above the WL curve level, in order to get to a higher room temp more quickly (at the expense of efficiency of course) but the system doesn't do that by default, its not got that capability.

Posted by: @iancalderbank

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In that situation, the flow temp follows the WL curve. The target room temp affects how long the system stays on, until that room temp is achieved. Not the flow temp.

Thanks Ian, that makes sense.