The value on the screen labelled 'Indoor Unit PHE OUT(Tw2)' is the temperature of the water coming from the heat pump, and you've guessed it, the value labelled 'Indoor Unit PHE IN(Tw1) is the temperature of the water being returned to the heat pump.

The PHE is the Plate Heat Exchanger located in the outdoor unit that transfers the heat energy from the refrigerant gas to the water.

Thanks again Derek. So these are what is referred to as Flow and return temps? Should they be that close? Will it affect efficiency if they are? 

As long as you don't close off too much of the system you can safely turn down a bedroom TRV.  If you shut  down too many you'll reduce demand and you may get cycling returning.

In my system you can't adjust weather compensation at night on a timer. I therefore just use the timer to turn the heating off from 12-5am.  The house slowly cools and warms up again in the morning by the time I'm up and about  Contrary to what some say, this does use less energy than leaving it on. There is a spike when it kicks in in the morning but it doesn't last long. 

Posted by: @craig1980

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Thanks again Derek. So these are what is referred to as Flow and return temps? Should they be that close? Will it affect efficiency if they are? 

A difference of 5C is normally maintained between the flow and return temperatures, which is usually done by raising or lowering the speed of the water pump. Because your system does not have a PWM enabled pump, it cannot do this automatically. You could try manually setting the pump to a lower speed setting and see what happens.

@kev-m yeah, I don't have a programmable temp set back either but quiet mode runs at less power. I can't really find any information on it though other than a video of the older Samsung and that it shouldn't be used as it causes defrost cycles. 

I might try the timer on the room stat, I think it has one. Thanks. 

@derek-m thanks again. I assume that is done with the button on the pump itself? I also assume that I should adjust both to the same?

@grahamh I know you were very heavily involved with getting the Samsung units popularised over here, could you shed some technical light (for the engineers amongst us) on why only Midsummer Wholesale are the only people using the PWM output from the MIM to provide speed control of the primary circulation pump?

I forget which one of your training videos I’ve seen but on one of them you mention ‘ignore this cable, we won’t use this on production units’ when referring to the PWM output.

Posted by: @craig1980

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@kev-m yeah, I don't have a programmable temp set back either but quiet mode runs at less power. I can't really find any information on it though other than a video of the older Samsung and that it shouldn't be used as it causes defrost cycles. 

I might try the timer on the room stat, I think it has one. Thanks. 

You could manually lower the LWT by using the WL offset, but of course it would require someone to raise it again in the morning.

Posted by: @craig1980

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@derek-m thanks again. I assume that is done with the button on the pump itself? I also assume that I should adjust both to the same?

There will be a button on the pump for adjusting the speed. I'm not 100% certain how your system is piped up, so try adjusting one pump speed first, then adjust the second pump if you think it is necessary.

Note the temperatures around the system before and after making any adjustments.

@derek-m yeah, I'd realised that. Unfortunately my bladder is strong enough to last through the night so I don't need to get up in the early hours yet. 🤣

I'm assuming you mean flow and return temps not rad temps? 

Posted by: @craig1980

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@derek-m yeah, I'd realised that. Unfortunately my bladder is strong enough to last through the night so I don't need to get up in the early hours yet. 🤣

I'm assuming you mean flow and return temps not rad temps? 

When I am testing systems I initially take readings at many points, then reduce the number of points once I discover which are important and which are not. You could measure the temperature on two or three radiators around your home.

The more important temperatures are of course the flow are return.