Sorry again for the delays …still recovering from my destroyed hard disk on my pc. Did not take a backup!!!
I currently have a simple Honeywell Home Thermostat that interfaces using a simple switch , or relay. The Unit uses a simple radio transmission to control the thermostat relay.
I am considering a continuous , non-switched control.
Samsung provides a “Thermostat Interface” , at great cost.
The Samsung “Thermostat interface” uses the F3/F4 common control lines between the Control box and the Heat Pump in my garden.
This interface converts 240vac to 24 vac Smart Thermostats.
Do I need this unit if using a “smart” European Thermostat?
The Interface unit can also use “Continuous control” of the Heat pump temperature, in contrast to the Switched Thermostats.
A continuous control can provide Voltage or Pulse width control of the Power demanded of the Heat Pump. Not switched , variable.
During the last month I have changed the 201* Settings on several occasions trying to control the room Temperature , Heat Pump Economy and Stability.
When cold , and tired, I have increased the Lower settings to 50 C !.
When warmer , and bothered about the Electricity bill I have reduced the Lower settings to as low as 40 C , before regretting this and compromising with 45 C.
Currently the temperature is warm enough that I can survive with head to foot thermal insulation and a lower temperature of 43 C.
The Higher 201 * settings have also been changed from -8 to -5, -5 being my current setting.
When the Heat Pump began overshooting to 65 C I tried to reduce these settings without success!
When unstable, the Weather compensation loses control, probably , I think, because of an intermittent Air Thermistor.
The Reduced Temperature operation during Weather control could also be cause ed by the air Thermistor.
My Temperature measurements are wildly inaccurate due to the K type sensors being attached to the pipes, and not into the water .
With the Water Law offset Thermostat set to 1.2 C the Water Temperature is set to 42.4 C.
The HP stays in this condition oscillating about 42.3 C.
Weather Compensation is working
Front Screen With Weather compensation AT peak operating point, set using 2091 Option 4 .
The white steam you refer to is completely normal, it is water vapour and is a result of the defrost cycle. When the ASHP fan comes back on it pushes the plume out in front of the unit.
Defrost cycles are completely normal and can happen more often when the outdoor temp falls below 4deg, dependant on outdoor humidity level.
With your method of switching heating off overnight, the heat pump is pushed a little harder when it does come back on. This means the coils at the back of your outdoor unit can become colder, attracting more moisture/ frost and causing a defrost cycle more often.
I don’t believe that the thermistor at the rear of your unit will be responsible for controlling your weather compensation. You will likely have another outdoor stat ideally located on a north elevation away from the heat pump to prevent inaccurate readings. Do you know if you have this installed? Christian may be able to advise on what this looks like.
I personally do not use a room thermostat but use the weather compensation only, there is no room influence and i find that, with the WC curve set correctly, the heat pump modulates perfectly well based on the outdoor temperature. My system lowers the WC curve based on the desired temp of the room, rather than taking any influence from the room itself. This allows me to drop the set point over night by around 1degree, enough that the heat pump doesn’t have to work to hard to return to temperature the next day.
My problem is with my well intentioned neighbour who has twice offend me the loan of his "oil filled Electric heater given that I am obviously in trouble. "
My other neighbour is a care home , who would not appreciate large clouds of Water Vapour/Stream.
As to the External outdoor sensor , apart from the photographed sensor I have none!
My “installer” did not install five major components in his “installation”.
I would not be the least surprised to find a sixth missing external Thermistor.
However, Now, I have only the projecting Air Thermistor. It must now be used to measure the outdoor temperature for Weather Compensation.
My major complaint is the instability of the Weather Compensation system, with the Heat pump , on two occasions charging the Flow water Temperature up to 65 C, with an accompanying display of white Vapour!
I must assume that the Thermistor is “probably” the culprit.
Again , many thanks Colin, I need to appreciate others experience.
My “installer” has now said that “he will attempt to get Samsung to Repair and upgrade my Samsung Heat Pump”.
We have a Vaillant heat pump so the controls etc are a little different to the Samsung, I am using the OEM controls as they work perfectly well for us.
I have now had a hunt through the Samsung installation manuals and see no mention of the outdoor temperature sensor, so it may be built in to the outdoor unit itself, as you had suggested. This seems strange as manufacturers are normally quite particular as to where the sensor can be mounted, but they must have designed this issue out.
Someone else with a Samsung can hopefully confirm the case with this sensor.
Meantime, I hope the Samsung tech can carry out some tests on your system and make sure it is working as designed. There is a Samsung Gen 6 on the heatpump dashboard performing really well, so hopefully you can get similar performance.
I have a Gen6 Samsung, there is definitely an outdoor sensor located on the rear of the unit. Here’s a photo of the unit with the top cover removed, I added a 2nd sensor next to the original sensor for extra monitoring:
My retrofit 5kW Samsung is performing well using stock controller and upgraded radiators, SCOP of 4.2 since installation in Aug 2022. Here’s a link to live data from my unit: Emoncms - app view dashboard
Defrosting with the accompanying steam is quite normal, all heat pumps will do this when the outdoorT is low, it uses a small amount of energy, my measurements show 0.088kWh per defrost, at about 0C outdoorT my Samsung defrosts every 1.5hrs, but the overall COP is still 3.7 which is good in these temperatures.
I use the Samsung controller which is located in my living space as the room thermostat. WC is used to set the flowT via water law and then the roomT is used to inform the unit when to switch on/off. I think using the Samsung controller rather than a third party thermostat gives the best results in terms of hysteresis etc. This is what Midsummer recommend in their Samsung quickstart guide.
We can see that the electrical consumption was 0.027kW and the power peaked at 1kW, the defrost also extracted 0.27kWh of heat from the house. The defrost cycle lasted 4min.
Mine if a 5kW unit, a larger heat pump will require more energy to defrost because it’s physically larger i.e more ice to melt!
I’m not sure what you mean here, the WC is set on the water law field setting page. These are my WC settings, what are yours?
Interesting - never understand why sometimes it matches well and other not. Always amazes me that it takes ages to correct. So if one rises more than the other, it seems to get stuck at a differential for a while. I see differences in reaction times as well as absolute value differences.
De-icing power / Energy
My DE-icing consumption is larger than yours with the energy needed to convert ice at -8 C to steam over 50 cycles sometimes amounting to 2 Kwh.
With a care home for a neighbour , I must not, however, emit large quantities of Steam.
I will run the de-icing diagnostic during a cold night to separate de-icing consumption from cycling consumption.
The 201* are the settings used by the Weather compensation system graph.
Your values are again ,different, in my, much colder, climate.