Hi

I have a Samsung Gen6 (5kW) running without a LLH or buffer etc. I basically followed Glyn Hudson's tutorial on Youtube. It works fine for me. I guess you need to investigate why they decided to put one in in the first place.

Heatgeek states the reasons for doing it as "High flow rate requirement in the system, high resistance across the system/boiler pump is too small, or multiple heat sources for the property". the link is here https://www.heatgeek.com/low-loss-headers/.

I would imagine the middle one is most applicable to you, so you need to be looking at 28mm pipes to the heat pump itself and then look at the pipe configurations to the rads to make sure they they can carry the heat required at a reasonable flow.Here is a good explanation of that https://youtu.be/1FYv1RnVDrI.

Also check pump sizing. (BTW I dont think your pump supports PWM which is a shame as the heat pump can use it to adjust flow rate automatically, see here https://thegreeningofrosecottage.weebly.com/blog/alls-well-that-ends-well )

As long as your radiators are all open I cant imagine water volume would be an issue, but you could check just to be certain.

@ecobaker They work reasonably well on open zone, just make sure you always have the minimum flow rate.

Attached is a manual with the open zone programmer settings.

The Samsung DOES NOT support pulse width modulation pump control below 45 Deg Flow temperature, below 45 Deg C it maintains a fixed flow rate of 100%. Not great.

@heacol @ecobaker

That isnt correct about the PWM Brendon. Here is my Samsung adjusting flow rate below 45C.

@bontwoody @heacol I'm not sure my system supports modulation either way. 

My pumps are UMP3 AUTO, with flow rate setting buttons on them, both currently set to max flow rate, so the heat pump cant modulate them. The secondary pump is permanently on and the primary pump switches on and off controlled by the heat pump. My flow rate round the system when heating is 26 lpm, appropriate for what Samsung recommends. I think my rate could be lower if I've done my maths right, around 16lpm. I could manually reduce the flow rates of the pumps and see what happens. I think my DeltaT is only about 2 degrees currently. Although I don't have very accurate monitoring. 

The volume of my system is over 48 litres just in the radiators, so I am well with in minimum requirments for the 8kw pump. 

@bontwoody That flow temperature is pretty close to 45 Deg C (43 deg C), it could be sensor drift that is causing the activation, it is clear that it is not activated at lower temperature. I have seen the official documentation, not publicly available. It is a great shame, as it has a detrimental effect on the performance of the refrigerant circuit. Possibly something to do with the finding that they become very unstable below 30 Deg C flow temperature.

I would be more concerned about the control strategy of the heating system, 45 Deg Flow temperature at 5+ ambient temperature? COP +- 3.5, pretty dismal. (unless you did this as a demonstration or hot water production)

@heacol @ecobaker

In the middle of renovating an old stone cottage and both my wife and I like it hot inside so higher than desirable flow temperature at the moment. Should improve next winter now I have finished insulating and radiator upgrades to the new living room. Still beating gas though.

@Iancalderbank pointed me to the PWM control possibility and I think he has an 8kW Samsung model. Here is the pump modulation again at a lower flow temperature of about 41C. Perhaps Ian can add to the data available.

Remove the llh and the secondary pump, wire the pwm line of the primary pump up to the Samsung controller…. That’s pretty much all there is to it.

@hughf The pump dosen't have a pwm line as its an Auto model

@bontwoody Maybe they have corrected it, I hope so.

@ecobaker ah damn…. Swap that out for a UPM GEO then….

Posted by: @hughf

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Remove the llh and the secondary pump, wire the pwm line of the primary pump up to the Samsung controller…. That’s pretty much all there is to it.