Welcome to the forums! I hope you’ll find the answers you’re looking for here; there are plenty of Samsung users around who might be able to help.

It’s no secret that most heat pump manuals leave a lot to be desired, and Samsung has long been known for having some of the least user-friendly ones.

While I can’t assist with your specific questions and will leave that to others, I’d be very interested to hear about Samsung’s level of support as you progress. Please do keep us updated.

Good luck with getting any info out of Samsung. Their customer service is known to be very poor and they rely on the brand name to get purchasers. How do I know?, well you can guess. I have a Gen 7 12Kwh and like you am still playing with temperature settings. On open circuit, ie no buffer and as far as I know only one pump. Manual almost useless. Great info and help on here though.

Hi @johnnyb 

I have the same heat pump as you but use radiators not UFH. 

You should be able to run the UFH on a lower flow temperature than radiators and the lower the better for efficiency and running costs. 

How do your radiators fit into the scenario as the will probably need a higher flow temperature than the UFH

The buffer vessel will have a negative effect on efficiency and I have heard the manufacture warranty demands it used often. 

Are you using antifreeze or anti frost valves?

How are you measuring COP as apparently there is a quirk in the Samsung figures you have to allow for. 

Thanks for the posts, I'll find out how Samsung respond in the new year. The installers messaged today to say they have emailed Samsung to ask for assistance and hope we will get an engineers visit, but said Samsung have already closed for Christmas so it will be the new year before they hear back.  They said they normally get charged £500 for a visit but are hoping it will be free as there seems to be an issue with our set up and another customer also having a similar COP.

@bontwoody According to a youtube video here it is less efficient under 30 or 35 deg. He did add a note later that after an update where it could control the PWM pump this was no longer an issue. I don't have a PWM pump, it's manual adjustment of the speed.  Agile is cheap again this weekend so I am going to turn the WC temps down again and leave it on low for a couple of days and see if it is any better. I'm also going to try to watch it to see if it is cycling and measure the flow and return temperatures.

The rad is a towel rad in the bathroom and is feed from the UFH manifold. When I suggested having it and running it this way I thought it would be good to dry to towels. When the flow temperature was 25 or under it didn't do much, at 30-35 it feels warm and does help dry the towels. They did tell me it wouldn't be much help but it wasn't difficult or expensive to put it in. It does help warm the bathroom most of the time when it is 30+degs so has some use.

We have anti frost valves.

I am using the Samsung figures on the controller, that's all I have at the moment.  Once the Homely set up is here I expect to be able to see a lot more.

@johnnyb So I think what might be happening is at the very low flow temperature you are trying to use, you cannot get the UFH to release enough energy into the house for the minimum output of the heat pump. If you can control the pump speed by PWM (I do) then it can slow the pump and the water will stay in the floor longer and increase the delta T making the situation better.

I had a similar problem and managed to improve it by moving my controller into my living room and using the inbuilt thermostat to stop the heat pump before it started to cycle (see https://thegreeningofrosecottage.weebly.com/blog/a-moving-experience)

Do you know what your flow rate is? Perhaps you can turn your pump down manually to achieve a similar effect to PWM.

Regardless of all of the above, if you can run at a flow temp in the 30s you should get good COP. Im getting 4-5 in that range. The only difference I can see between our systems is you have a buffer. Depending on your situation, you might be able to turn that into a volumiser although I would image the volume of water already in your system would be sufficient for a 5kW Samsung. If you know how much UFH pipe you used you can calculate it.

Posted by: @bontwoody

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How are you measuring COP as apparently there is a quirk in the Samsung figures you have to allow for. 

@johnnyb If it is any help, I calculate the COP / SCOP using the following formula for my Samsung heat pump

( Energy Generated + Energy In ) / Energy In = COP

So for example, on a day where my local outside temperature was a constant 6 C all day (12th Dec 2024) my system generated 84.6Kw and consumed 26.1 Kwh

This gave me a COP of: (84.6Kw + 26.1Kwh) / 26.1Kwh = 4.24 for that day.

To verify the formula is correct, my calculated heat loss for an inside temperature of 21C and outside temperature of 6C is 6.7Kw per hour.

This would in theory make my system consume: Heat loss / COP = 6.7Kw / 4.24 = 1.58Kw per hour of electricity

The system ran a total of 17 hours that day so consumed electricity at a rate of:  Total Electricity Consumed / Runtime = 26.1Kwh / 17hrs = 1.53Kw per hour 

So both results of 1.58Kwh and 1.53Kwh are very similar giving me the confidence in the above COP formula

Hope that helps 🙂

@technogeek Thanks for posting that. It does make sense now you've pointed it out,  but I haven't realised the energy generated needed adding to the energy used, and I don't think the installer did either as I gave him figures for the second week and he said my cop was just over 2. Even more worrying that they don't know how to interpret the Samsung figures!

If this is correct it means the best day the cop was 4 and the other days this week it was 3.5 or better.

@johnnyb This formula does seem a bit contenious, but the results do seem to me to be closer to what is expected (obviously not to everyone though see https://renewableheatinghub.co.uk/forums/renewable-heating-air-source-heap-pumps-ashps/new-samsung-12kw-heat-pump-help/paged/3#post-38938)

The Vaillant heat pump controller has exactly the same glitch when trying to calculate COP.

@johnnyb to be fair I did not know in the beginning either. I had to do my own research and experimentation to understand what was going on.

This link has a graphical representation of what the formula is based on http://labman.phys.utk.edu/phys136core/modules/m3/refrigerators.html

Q1 is the heat harvested from the cold store (outside air or in Samsung speak "heat generated"), the work done (electricity consumed) W which are both added together to create Q2, the heat store (inside of your house). This sum is divided by the work W done to give you your coefficient of performance, COP.

COP must not be confused with efficiency (Output / Input) because that would imply you are creating energy from nothing (to get 400% efficiency) and the laws of physics states you cannot create or destroy energy, merely convert it from one form to another.

Kind Regards

@bontwoody Thanks for your posts, and the link to your blog. a very interesting project you have there.

I have tried different speeds on my pumps but with some the pump switched off and others the deltaT just got smaller, down to 0.5 at one point and then the pump switch off.  With a low flow temperature deltaT gets a little smaller I think, but mostly it is around 1.5-2, it is set to 5 in the settings and that is what it gets to with a DHW cycle.

Interesting about how to read the Samsung figures. At the moment my installer is reading it as a very low COP and it has got their attention so I will let them continue to question it.  Once I am on the Homely trial I should have more data and be able to see how much energy is actually being used and produced.

I have several more questions after reading your blog, it looks like you set your up yourself?  There are several settings I would like to try adjusting but I don't want to cause any issues or lose track of what I have changed and what affects they are having.

The field setting value (FSV) 4051 on my system is set to Use(100%).  You said you had to change yours to off for your pump to stop running continuously on the original pump.  My pump doesn't run continuously but I wonder if that is affecting my set up. Did you change both the positions of the wires and the setting at the same time? I would assume you did and don't know if the setting made the difference or the cable positions

Did the PWM pump make much difference to your COP and help things run better, was it worth changing?

When you had the cycling with the low flow temperatures was it affecting the COP? I don't think mine cycles, the primary pump is always on and I think the outdoor unit is always running when the pump is but haven't sat beside the outdoor unit to watch it as it is wet and windy today.  I also think that with FVS 2091 set to Use (signal on/off) it stops the unit cycling, but I'm not sure if I have understood that correctly or not, it might just be the primary pump.

It looks like you had the flow at low 30's in your graphs, but said you'd set the water law temperatures at 38 to 45.  Do you find the flow temperature is several degrees lower than you have it set in the waterlaw temperatures, mine seems to be.

DO you know what the settings need to be for the Samsung display unit to acts as the thermostat and control the heating?  I have an external thermostat fitted but want to try using the Samsung controls as you have done to see if it works, the thermostat I have seems to have a mind of it's own.  I found settings somewhere online but when I tried changing them a couple of days ago the secondary pump didn't switch on.

I love your EV. We looked at the i3 several years ago, and loved it, but bought an e-Golf as VW had a great deal on back in 2017 and the price was about £10k cheaper. We still have it, but look at i3's and still think they look a great little car.

@johnnyb Thanks :-). I’m off out on a Xmas do tonight but will sit down and try to answer as many of your questions as I can tomorrow.