Posted by: @antonical

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It's seems to be stuck at 18.5Deg internal temp. Regardless of the thermo settings on teh remote control. 

The installer is suggesting we adjust the water law up by 1 deg per day to see what the impact on the real world building is. We are used to 21 deg and the house is definitely cold.  We mistakenly thought by putting the thermostat up it would just ge there but seems stuck at 18.5 Deg. 

Any suggestions from the Samsung veterans on here would be appreciated.

Your installer may well be right.  If the WC curve isnt set high enough the house will never reach temperature irrespective of the set temperature value, because the rads wont be emitting sufficient heat to offset the energy lost from the house.   Are you operating 24x7 with TRVs all open?  If not then do that first, leave for 24 hrs and see what happens.

If you are operating 24x7 with TRVs all open then I suggest you do what your installer says.  Better still, before you do,  turn the set temp up to say 23 and adjust  the WC curve one degree per day until the house is just at the right temp, which is the way to optimise the WC.

@jamespa Thank you for taking the time to reply. 

Interestingly, the TRV's are all open but the lockshields are not as they spent a while with a thermal imaging camera looking at teh flow and return temps on each rad to get a delta of ~5 Deg across all of them. It's a large house on 3 floors with a total of 16 rads excluding the towel rail etc. 14 most are new larger rads. The system is fully open loop. 

A day further on and approx. 38kW of electricity the house is now at the set temp of 21 and has stayed there. The system is running constantly 24x7 apart from about 40 mins for DHW in the middle of the night. We tried setting the internal control target temp to 24 for the overnight section. We have a TOU tariff so energy about a quarter of the price between 00:00 and 06:00 expected to wake up to a warm house but in reality all we did was use more electricity and 21 degrees. 

The installer changed the water law parameters on install from the default Samsung 15Deg 35Deg to 10Deg 35Deg 

Here is a pic of the monitoring dashboard. It would seem that lowered the WL flow temp a bit depending on outside temp. Which has been pretty low over the last few days 6-9Deg.

At this rate maintaining a not comfortable 21 deg house is about 17.5mW a year of electricity!

@antonical 

Im not sure I entirely follow you but in summary are you saying that the house is now heating satisfactorily?

Your 'overnight heating' experiment may need a few days to settle down and there may be reductions in the daytime consumption which you wont easily see, so I would not rule out the possibility this is helping with cost.

Re:

Posted by: @antonical

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Interestingly, the TRV's are all open but the lockshields are not as they spent a while with a thermal imaging camera looking at teh flow and return temps on each rad to get a delta of ~5 Deg across all of them. It's a large house on 3 floors with a total of 16 rads excluding the towel rail et

At least one lockshield (usually the one furthest from the heat pump) should be fully open otherwise you are unnecessarily restricting flow.  The others should then be balanced against that.

Posted by: @antonical

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At this rate maintaining a not comfortable 21 deg house is about 17.5mW a year of electricity!

Why is 21C 'not comfortable'?

If your house loss is really ~16kW then the expected heating energy requirement is 32-48MWh/year.  Thats energy delivered to the house not electrical energy consumed.  Assuming a SCOP of 3-4 this translates to 8-16MWh/yr electricity.   17.5MWh is at the high end of this range.  How are you getting to this figure please?  Are you measuring electricity in or heat out; if the former is suggests a COP of 1 or even less which would indicate a faulty heat pump.

@jamespa HI thanks for your note. It may be just early days and a lack of understanding on our part. Not long after I replied earlier is shut down for a while. It had reached its 21 degree target for a long time but that is as measured by the remote controller which is on the first floor landing where the old one was. Not sure why it shut down many many hours after it had got to 21 degrees. Maybe there needs to be an offset somewhere reported temp by controller vs actual temp as measured in various places around the house and averaged. The house is not a comforatble temp with a setting of 21 degrees. So we have just put it up by 1 degree and see what that does.  

I am still getting my head around the water law and internal temp setting and how they work to get the house heated. 

Is this the correct analysis.

The Heat pump determines its flow temp using the outside temp and the water law curve that then dictates its target flow temp to circulate around. The internal setting then works with this to get the house upto temp and signal that it has done so. It took quite a while to bring the house upto 21 degrees. Its now working hard to recover some of that loss I suspect after shutting down. 

The water law the installer set is significantly differnt to the Samsung one. 

Samsung is a much gentler curve with the incremental one being the most aggressive and 'hottest'. This was the installer strategy it seems. Change WL settings up by 1 degree at top and bottom. At curent 7 deg ouside the Samsung curve would already be hotter by almost 3 degrees. 

Is my undertstanding correct. The system is in heat mode not auto.

Cheers

Posted by: @antonical

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Not sure why it shut down many many hours after it had got to 21 degrees. Maybe there needs to be an offset somewhere reported temp by controller vs actual temp as measured in various places around the house and averaged.

Depending exactly how the Samsung is configured you have two competing control loops namely the one based on the temp sensor and the WC control.  Because the house takes a very long time to heat up or cool, the control from the internal temperature sensor is probably causing the long off periods you see.  Do yourself a favour and simplify things by setting the set temp to well above the figure you want, say 30C, thus disabling the control loop based on the internal temp sensor.  Then adjust the WC up or down by one degree per day until the house settles at a comfortable temperature.  This is best done when its very cold, so it may be you have to make an initial adjustment now but tweak again mid next season. 

This 'pure wc' mode, if adjusted correctly, is anyway the most efficient and frequently the most comfortable way to run a heat pump.  Once the house as a whole is about the right temp you can turn down or up the lsvs a bit on the radiators in rooms that are overheating, balancing for equal room temp (currently they are balanced for equal dt, which is fine but assumes that they are perfectly sized).  

Don't worry that the water law is different from the default, it has to be adjusted for each house.  The idea is that house loss is determined by oat, and rad output is determined by flow temp, so get the relationship between ft and oat right and the rad output will, at any oat, match the house loss thus keeping it at a stable temp.  Personally I would set the high oat end at something like 30 at 15 and then adjust the low oat end only at first.  The rationale for this is that, once the oat is above about 15, you barely need any heating whereas at 10-15 the amount of heating you need is still changing so the WL temp should still be changing.

Many on here don't bother with any room influence at all and just run on pure WC, or alternatively use the temp sensor or trvs on a few radiators only as limiters set a couple of degrees above target, eg to deal with rooms where there is sometimes high solar gain.  I run my heat pump on pure WC and it has never been more comfortable.  The only exception I make is at the very end of the season, where solar gain is high and loss is low.  At this point I switch to WC plus a limit that switches off the heat pump when the room temp is more than about half a degree above target.  The rest of the time its pure WC.  I did try WC + room influence in the main part of the season but, like you, I experienced unwanted cooling when the internal sensor turned the heat pump off, due to the long house response time.  I disabled it and, as I say, the house has never been more comfortable.

Just one more comment worth making which is about humidity.  Some people, me included, are sensitive to humidity.  This may cause particularly damp days to feel colder than drier days, even though the actual temp inside is exactly the same.  There is not much you can do about this other than have the set temp permanently a little higher than you otherwise would, use a dehumidifier, and/or air the house.  When its misty outside airing the house wont help though.  Its something to be aware of rather than something to worry about.

It might be a good idea to read this introduction to heat pumps and this article on radiator balancing to give you some background understanding.  Its early days so take it slowly and methodically, you will soon get used to it and. with a bit of luck, wonder why you put up with your old boiler for so long.

@jamespa Many thanks for the note and ideas. the system is now in full auto mode on Water Law. Using the previous method then with the temp as reported by the indoor controller showing 23 degrees the house is OK (complaints have stopped)  It will be interesting to see how the power usage looks after a few days. Today is a great solar day so a very cheap running day!

Cheers