What Is the Waterlaw or How I think the Samsung Gen 6 HP works

[marc1]

Hi,

The purpose of this post is to pull together everything that I currently understand about the Samsung Gen6 ASHP. I have figured this out from a lot of different places in dribs and drabs and thought it might save others time to put it all together. Please feel free to comment if you think I’ve got anything wrong.

 

Like most people I have no desire to know how the thing works. However I have a desire that it DOES work and mine simply doesn’t seem to. When I go back to the fitters they seem to have no understanding of what they have fitted and set the system by reference to some clip on youtube!

 

 

The place to start is with something we all know. How quickly something loses heat depends on how hot it is in relation to the surrounding temperature. If your hot water bottle is 1 degree above the temp of the bed it will take it a long time to lose that 1 degree but if its 20 degrees hotter it will cool much more quickly.

 

So how much energy you have to put into your house to keep it warm varies depending on the outside temperature.

 

It is also affected however by how good your insulation is and the particular characteristics of your home. The most obvious one of these is its surface area.

 

The Samsung system deals with these issues through its “water law”. What this is aiming to do is to get the house "up to temperature" and then to balance how much heat is being put into the house with how quickly the house loses heat. It does this by changing the heat of the water in the radiators. So the greater the difference between the internal and the external temps the hotter the water to offset the increased rate of loss of heat.

 

This is why if you go into the settings you will find two sets of numbers. To get to these figures you need to cover the up and down buttons on the panel (at the same time) and hold them until a password screen comes up. The password is 0202 and gets you into the service mode. Do not worry you wont break it! Once in service mode press the “up” button on the screen to take you to “field setting values”. Click on this and then go down to “water law”. Once into the water law settings you will find a setting called “outdoor temp”. Go into this setting.

 

You will see two numbers which allow you to set temperature parameters. Below the lower parameter the system will deliver the hottest water to the radiators. Thus if we assume that you want the house to be at a constant temperature of say 21 degrees then if you have set the lower temperature as being say -2 degrees then if the outside temp falls to that figure or below then the system will deliver the hottest water to the system. At the other end if you set the higher temp to say 15 degrees it follows that once the temp goes above that figure the heat of the water being delivered to the radiators will be at its lowest level reflecting the fact that the loss of heat from the house will be much lower if the difference between inside and outside temps is 6 degrees (21 – 15) than if the difference is 23 (21 - [-2]).

 

If then the temperature is somewhere between 15 and -2 the system will progressively increase the water temperature in the rads as the temperature falls.

 

So that is your first set of variables.

 

The second is the chosen water temperatures at the upper and lower ends of the temperature scale.

To get to these go up a level from the outside temp settings and look for “water out temp”. You will find two of these being WL1 and WL2. Set both to the same settings.

 

Rather oddly when you look at the numbers on the control panel the higher number is described as “low”. The reason for this is that it cross references to the “low” temp in the other set of variables. Ie when the outside temp is low the water temp needs to be high!

 

You can then input how hot you want the water to be in the rads when the temp is at the lower external temp previously selected. You then input the “higher” (actually lower) temp figure to set the water temperature at if the external temp is warmer.

 

Assuming your system has been correctly installed (mine isn’t and they are coming back to change the size of the piping!) then those 4 variables allow you to set up the system so as to balance loss of heat with heat input so as to deliver the desired warmth in the house.

 

However having got to this point it occurred to me to wonder what happens if you just collapse the parameters by setting both figures for delivered water temp to say 47 degrees. In that case the system simply delivers water at that temp to the rads all the time unless and until the thermostat tells it to stop.

 

So what’s the points of the variables? As far as I can make out its all about efficiency. This is one of the claimed good things about ASHP’s. They are claimed to be very efficient. This efficiency is expressed as a figure known as COP and what that measures is the amount of energy out for energy in. You will see claimed figures of 4 ie for every 1KW of power consumed by the monster it gives you back 4KW of heat.

 

But if you look at the figures on the graphs on the panel (accessed by using the “wheel” on the panel to take you to a “settings” screen. Choose “energy” and then “energy usage” which will take you to graphs showing energy consumption and energy generation ie heat out) you will typically see a ratio closer to 2.5/3 if you collapse the parameters.

 

I assume that to get closer to the claimed 4 you have to get the parameters right so that the HP works at its most efficient (like all machines there is a “sweet spot” for best performance and that is not to be found when its running “flat out”).

 

So having established by collapsing the parameters that your HP can do the job you then need to play around with the parameters to find that sweet spot in which your COP figure is as high as it can be but your house is as warm as you want it whatever the outside temperature.

 

My guess is that this spot can be found if you have the right equipment to look for it but I haven’t and it has been very clear to me from the fitters that they simply don’t understand how the system works and you should expect no help from them.

 

So over to you and a long process of trial and error to find the magic point.

 

PS. You may notice that on the front screen on the panel there is a number “0” on the left side of the screen. This number can be adjusted up to “5” and down to “-5”. What I think it does is to move both the “upper” and “lower” temp figures within the “water law” by up to 5 degrees either up or down.

[BotusBuild]

Marc,

Thorough write up. Well done for taking the time to do this.

 

Sounds like Samsung have chosen to rename what the majority of ASHP manufacturers refer to as Weather Compensation (WC) to Waterlaw.

 

The settings you describe are the details of what that majority refer to as a WC curve (strictly a few straight lines).

 

[ReedRichards]

Well it looks like it's Load Compensation as well as Weather Compensation if it boosts the output to get the house up to temperature.  Heat pump manufacturers seem to delight in inventing their own terminology for processes that are well-establish and named  for gas boilers.  And no two heat pump manufacturers use the same terminology, as far as I can see.  

[ReedRichards]

9 hours ago, marc1 said:

My guess is that this spot can be found if you have the right equipment to look for it but I haven’t

 

I don't think any specialised equipment is needed, just a lot of time and patience.  If you can't get your house up to the desired temperature then whatever output temperature is being called for is set too low (for that particular outside temperature).  Eventually you should be able to map out what output water temperature is needed for the range of outside temperatures you encounter.  Then you set your weather compensation ("Water Law") parameters to match that.

[Andehh]

Bookmarking to have a thorough read later! Thanks