Posted by: @mike-h

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Yes he does - If Greener Living source the Samsung from Freedom Heat Pumps, then the buffer tank is required as part of the warranty (personal communication from Fergal at Freedom).

<spits blood> even grahamh the man who was freedom, advocates bufferless now.

Posted by: @swanny

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The installation has a buffer tank in the loft and hot water tank in the airing cupboard on the first floor.

The installer was Greener Living.

oh B411s, thanks, missed that. In that case @swanny we need to know: you will have two circulation  pumps , one pumping each side of the buffer. Where are they, what type are they, and what settings are they on,?are you able to install some cheap digital temperature monitors on the pipes going in and out of the buffer? which will be not fun I guess if its in the loft.

the objective is going to be to try to balance the flow rates and temperatures either side of the buffer.

@iancalderbank the objectives noted with thanks. If I understood your water law entries correctly, my water law should be same as yours (photos attached) - decided to start somewhere that works for someone to start with.

I have also made sure values in FSV 203* are same as FSV 202 as suggested by @mike-h. I made these changes last night and have all TRVs fully opened. I tried balancing the system back in December and think Greener living had already done it as there was very little air from 2 rads.

In terms of results, temperature was a stable 20°C through last night and has been 21.5 all day today. It’s been relatively warm today at 10°C outside temp. and sun has been out so planning on leaving things as is for a few days and observe any changes to adjust as necessary unless there is something wrong that could be pointed out from the photos below. Instantaneous energy consumption has been around 800W to 1.4kW from what I have observed which is impressive. I have turned the thermostat up to 25°C so the system has been running continuously from last night. 

I am rather surprised at how warm the house has been given the radiators do not feel warm at all.

@swanny That's looking really good. I imagine your flow temperature with those settings is around 32 degC if OAT is still 10 degC. Your inverter pump value is showing at 25%, which means that in a properly designed system with a single pump and no buffer, the pump would be reducing the flow to control the returning water temperature (RWT) from rising too much. The difference between LWT and RWT is known as Delta T and heat pumps are most efficient when Delta T is kept around 5 degC.

When it is mild outside, the heat pump will be supplying less heat as demand is lower. Heat production is proportional to flow rate and delta T. With a fixed flow rate pump like yours and mine, delta T has to fall (RWT rises while LWT remains the same) and when the limit is reached the heat pump starts cycling off and on. Operating at a lower delta T and cycling are both causes of reduced efficiency. It is said that reducing flow to maintain delta T around 4-5 improves efficiency and reduces cycling. To do this requires a single loop system and a special pump called a PWM pump as in @iancalderdale's system. I have never seen my inverter pump value below 100%, so was interested to see your value of 25%.

It would be worth keeping an ear out for cycling. Depending on your settings in FSV 2091/2092, when the compressor stops (cycles off) your water pump will either keep going or continue for 1 minute and then stop until the compressor cycles on again or run for 3 minutes and be off for 7 minutes etc until the compressor restarts. When my Samsung cycles it does it 7-8 times an hour, which is supposed to cause premature wear and tear. The buffer was supposed to prevent so called short cycling, but I think it made it worse by prematurely reducing radiator temperatures and therefore heat demand.

Can you send us a picture of your buffer tank? If it is short and squat like mine was, there is little chance of preventing mixing of leaving and returning flows as the pipes are only a couple of inches apart.

If your pipework is suitably sized, then you may be able to persuade Greener Living to remove the buffer and additional water pump, replace the two high resistance Honeywell valves with a low resistance 3 way valve, fit a mandatory strainer and insulate your external pipework to MCS standards. See this post from a professional installer ( https://renewableheatinghub.co.uk/forums/postid/26159). If we all insist on properly designed systems, maybe Greener Living and their ilk will take the hint. They may say that Samsung insists on a buffer, but one of the members of this forum was told by GL (when they discovered there was no room for a buffer) that a buffer was not essential! They still fitted 2 pumps though.

I am not sure how to get the message out to all the prospective Samsung owners though.

I've got a Samsung pump and there's nothing about a buffer in what I have read of the bumph that came with it.  My system doesn't have a buffer tank either.  So greener living etc can gft.

@mike-h is your pump still cycling 7 times an hour?  That's nuts, maybe we could do a sweepstake on when it will break down.

@guthrie No, only when it cycles does it cycle 7-8 times an hour. Most of the time it doesn’t cycle at all because it doesn’t reach its minimum output. Who supplied your Samsung? It’s Freedom Heat Pumps who claim the warranty is void without a buffer. They supply Greener Living ( or they did in my case).

@mike-h  I have attached a photo of buffer tank as requested. I will speak to Greener Living about it but tbh, have no faith in them doing everything. I am still chasing them to return and complete some outstanding work they lost interest in after taking full payment 4 months on.

Is the 25% inverter value any good or bad?
I was previously using the sound from the pumps to go out and check for cycling but with the pumps now on permanently, I have no way of checking any more as the ASHP cannot be heard from the house.

i have also attached photos showing the values for FSV 2091/2092. Any observations welcomed. 
Photos also included for the pumps as requested by @iancalderbank earlier.

Posted by: @mike-h

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@guthrie No, only when it cycles does it cycle 7-8 times an hour. Most of the time it doesn’t cycle at all because it doesn’t reach its minimum output. Who supplied your Samsung? It’s Freedom Heat Pumps who claim the warranty is void without a buffer. They supply Greener Living ( or they did in my case).

Phew, hopefully it won't die too quickly then.  My Samsung was installed by SHS heating and renewables ltd, they have been doing installations for some years now.  I imagine they buy a bunch of them in from the Samsun dealer for the UK, whoever that is.  It is paired up with a Joule hot water tank, which apparently is okay except sometimes has QC issues then joule ignore you after it breaks and refuse to fix it.

@swanny good progress. 1kw is a good start. the fact its showing 25% on that "inverter pump" number, means it would be trying to slow the pump down if it could, it means the compressor in the heat pump is not running flat out. which is a good thing, and is  proven by you seeing the 800w to 1kw on input. on a mild day this is all a good thing.

I'm a bit puzzled by your system. I can only see 3 pipes into the buffer. Is there another one hiding round the back or are there definitely only 3?  3-pipe is a valid design, and could be better in fact, I just haven't seen it before in a forum users system, these installers all seem to use 4 pipe. I can also see 3 circulating pumps in your airing cupboard. 2 is normal with a buffer. 3 implies an extra one for ?something? can you draw a "follow the pipes" line diagram for your system?

constantly running weather comp radiators at 33-35C don't "feel warm" like your used to . but they keep the house warm. it takes a mindset change.  about 36C they start feeling warm.

if you want to check for cycling properly, and get more than just the basics of performance checked, you'll need to start installing some flow temperature and electrical load monitoring.....welcome down the rabbit hole

Buffer B---S---: I actually did the samsung installers course, provided by samsung themselves online. Their position: you can install a buffer or you can not. Provided you comply with minimum flow and volume requirements, both are valid. They were very cautious and basically avoided the question when asked which is recommended (my supposition is because they don't want to p**s off all the installers who put buffers in).

midsummer wholesales installer schematics says both are valid 

FSV 2091: change to Use on/off + WL interlink 3 (or something like that) the extra bit allows an overrun thats in the manual.

@swanny I tried FSV 2091 setting 'Use (Signal only ON/OFF)' to see if it would stop it cycling when mild outside and LWT was low. It did prevent it cycling, but instead the LWT rose above its setpoint and consumption rose by quite a lot. So I went back to 'Use (Signal ON/OFF) or WL Interlink OFF(Water Pump1)'. With this setting, you will hear the Water Pump switch off 1 minute after the compressor stops and then restart when the compressor cycles back on. This is useful for detecting cycling if you don't have any extra monitoring installed. Before April 2022, heat meter monitoring was usually installed routinely as part of the Renewable Heating Incentive (RHI).

'Use (Signal ON/OFF) or WL Interlink OFF(Water Pump3)' means that the water pump will run for 3 mins, be off for 7 mins and on again for 3 mins etc until the compressor restarts.

@iancalderbank  there are indeed 4 pipes connected to the buffer tank. I unfortunately don’t have a clue on direction of flow. All I see are pipes 😀 

On the WL interlink, what determines whether it should be 1, 2 or 3?

I am wanting to use the wired controller for heating instead of the nest. My thinking is this means pumps coming on only with the main unit and stop the continuously annoying sound. The pumps have been on continuously since I turned the thermostat up. Does this affect the system? I’d hope not as it is the default controller.

@swanny the different WL interlinks values are different timing options for the overruns. 3 was what was recommended to me in lots of material I read prior to install, that's all. Suggest downloading a copy of the controller settings manual at this point, it'll be useful. here . I'm assuming your installer didn't leave you with the copy that would have been in the box.

if you want to move away from the nest thats great. But you need to check how your pumps are actually being activated, particularly the secondary side one how its it wired. and what is the 3rd pump.

annoying sound what do you mean?

@swanny The accepted way to run a heat pump is to have it on 24/7 which means the water pumps will be on 24/7 (low and slow mode). The weather compensation allows for variations in outside temp, so when the settings are correct the home is kept at a reasonably constant temperature. Some people want a reduced temperature at night, so using the wired controller in room temperature mode would allow this. The scheduling to do this is a bit tiresome as you have to set the times when you want a different room temperature separately for each day of the week! When you are in room temperature mode, you can't vary the LWT via water law settings with the offset button. Instead you have to change FSV 202* and 203* which is a pain if it is just intended for a few hours.

I expected that when using room temperature mode, the wired controller would reduce LWT and/ or compressor speed and hence consumption as the room temp approached the set temperature. However, it simply switched the heat pump off just the same as a third party thermostat would. Bit disappointing.