Posted by: @ardmark

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Does anyone know what the maximum recommended flow rate for a Samsung 8KW Gen6 heat pump is? My flow rate is 28 to 30 l/m which seems a bit on the high side from what I've read. System works OK although pipework is a little noisy. Circulating pump looks like a Grundfos UPS2, the 8m head type.

Thanks.

 

The minimum and maximum flowrates should be detailed in the specification section of the installation manual.

@derek-m You would think so but there does not seem to be any information about actual flow rates in the installation manual, only that the pipe work must allow for the minimum flow rate which is not specified. I have read elsewhere that the minimum should be 16 to 20 l/m, so I will try turning my pump down and see if that affects performance adversely.

According to my installation manual for 12kW unit, AE   RXYDEG/ AE   RXYDGG, the minimum requred water flow rate for operations is 16l/ min.  I can't see a maximum flow rate in the manual.

Thanks, it looks like I have some room to reduce the speed. Hopefully it will cut the pipe noise down a bit.

Hopefully so.  I should have mentioned that our one is also a Samsung Gen 6, so I don't think there will be many differences even if slightly different sizes. 

@guthrie I finally managed to get the pump speed reduced, and I have a few observations now which may be useful to anyone with flow rate concerns.

My pump is a Grundfos UPS2 8m head type, and you have to hold the button down with some force for a few seconds (I had to use a screwdriver handle), after which you need to press it a few times to cycle through the Proportional Pressure mode and back into the Constant Pressure mode (details in the pump manual). If you set it to PP by mistake, the speed drops dramatically. 

Having set the speed to setting 2 (which I did whilst running the pump in self-test mode), I immediately noticed a reduction in radiator noise, and also the heat pump itself seems to bee a little quieter for some reason. However, there is also a drop in heat output from the rads, to compensate for this I have set the low Water Law (weather compensation) temperature a couple of degrees higher: it was set at -4, now it is at -2. I think this is a worthwhile tradeoff, but I would not want to drop the pump speed any more.

My pump flow rate is now 26 l/m, on setting 2, and it was 31 l/m on setting 3. So it looks like you really do need a good flow rate with this heat pump, not just the minimum specified, for the system to work efficiently. I have no idea if 31 l/m is too high for the Gen6, I would doubt it but it does seem to like the lower flow rate better.

Hope this information is useful to someone.

That is interesting to know, I should try and check our pump speed, but our system is pretty quiet in operation, aside from the general heat pump noises with the fan.  We have no radiator noice at all either. 

Out of interest, did you inherit your system or was it newly installed?  I do like to know why things are out of kilter in a system.

samsung G6 flow rates for all sizes

MIDSUMMERWHOLESALE.CO.UK "https://midsummerwholesale.co.uk/pdfs/monobloc-datasheet--2-.pdf"

@ardmark I think you said as a consequence of dropping the flow rate , you have had to increase the LWT by 2C to keep your house warm ? if so you'll now be running less efficiently, for the HP to produce that 2C higher LWT will have lowered the COP a few decimal points. if the HP got quieter when you dropped the pump speed, that just means the HP was working less hard. that could have been a temporary thing - any short term change in the system such as a substantial change in flow rate, the HP will take a while to "rebalance" itself. 

suggest you make sure that all your radiators are balanced and taking their share of the load. A drop in flow rate can mean that a radiator that is "harder to get to" (because they aren't all quite balanced) drops out of the active circulating system.  If done correctly, that should mean that no Weather Compensation settings change is needed.

@iancalderbank Yes I think you are right about the efficiency, although I am not too worried as I am on a dual rate tariff - I get 14 hours a day of off-peak power (yes, 14), so I run the house a little warmer during the day off-peak times and a little cooler during the peak rate times. It averages out at about 15p / KWh, so I only need a COP of about 2 to match the cost of gas. And I am getting better than that now anyway. And that is not withstanding the power coming from the roof!

Now you mention it, there are some differences in 'emitter' temperature as you move further away from the pump, so I'll have a look at balancing them - the installer never bothered to do this, in fact he never actually tested the system at all, and therefore didn't notice that he'd put the temperature sensor valve thingy on backwards and only fitted a single pump with a low loss header. 🤪