Samsung Gen 6 8kW Efficiency

Hardware Heatpump
141

its hard to tell exactly what the HP is doing because you only have power data in the graph, not flow rates or flow temps.
But the best guess explanation is not enough emitters area (at this lower WT) to cope with the min power of the HP. the HP is putting heat into the system faster than the emitters can take it out.

suggest you work out the power output of each radiator at the temperatures in question and add them up. there are plenty of tools for this online.
then look at the effect of upgrading to K2 or K3 radiators.
If you look at the earlier posts from @Madsen68 he stabilised his system by adding two K3 radiators in an “informal install” on flexible pipe in his garage.

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142

My 30-40 min cycling seems to be fairly independent of outside temperature.
I too have FSV 2093 set to pump 3, so that is a promising start for you.
Be aware that some roomstats can easily send signals to the MIM which confuse it into unpredictable behaviour (e.g. rapid cycling). I had to re-programme my Honeywell’s internal settings to increase cycle time.
Sarah

143

Flow rate is constant around 15 l/m. Flow temp at 7C outside is around 36/31.

I understand that maybe this HP was not a good choice since it’s minimal power input is around 1KW nd 4KW output, I just don’t understand how can I set it in way that simply it should work according controller thermostat. Why it has to cycle to often ? Can it work in a way that simply it heats to desired temperature then it switch off compressor and then starts again after half an hour when the thermostat signalize temp went down by XX degree celsious ? Really cycling every 7 minutes is contra productive here. At 7C outside it takes a while until a temperature drops and if the water is cold then probably there is a good efficiency so it can transfer lot of heat into it when there is warm outside. But this constant cycling is just horrid. At this stage I think some extra K3 radiators would help. Simply my house has heatloss 2.5KW@7C and 22C indoor. If this unit has min output 4KW it’s clear it has to cycle. I only don’t understand why it has work like this. I think there must be something wrong in the configuration of the pump.

144

Hi Michal,

My idea, may or may not work.

Try turning the flow rate down, I am sure it will give the radiators more of a chance to deliver the heat produced.

I don’t have any experience of Samsung heat pumps, only Daikin.

But this is what I would do.

I would assume it is cycling because the water comes back to hot.

In addition to lowering the flow rate you may need to up the flow temperature.

As Ian said, you need to match the flow temperature, flow rate and dT so that the radiators can deliver the minimum output of the heat pump.

I had to do this with my Daikin, I found a flow rate and temperature that was stable, the increased radiator sizes so I could run at a lower flow temperature but the radiators can still deliver the heat produced, otherwise COP is poor and the heat pump cycles a lot.

145

I don’t understand why yours is cycling the same way regardless of outdoor temp. Makes no sense or ? There is brutal difference if there is -5 and when there is +5. While at -5 my house needs 5KW which the pump covers easily. At +5 it needs only 3KW or so and here it struggles because compressor can’t get lower than 1KW.

This was set to pump 3 :frowning: cycling like crazy… What honeywell settings ? what is it ? Can you tell me what the difference with pump 3 and the one without pump ??? I totally don’t understand this.

Can you also tell me how can i setup temperature on the remote controller ? I can see it shows the room temperature but it is used there somewhere for pump ? I simply can’t set desired room temperature anywhere. I’m crazy from this.

Jesus, on my electric boiler I’ve set temperature to 22C, set TRv and all worked… How to do similar with the pump :slight_smile:

146

there are two ways it can be cycling;

  1. emitters aren’t enough (with the WT and flow rate in use) to emit all the input that the HP gives at minimum power. WT gets too high. HP cycles. 7 min / 3 min has been seen many times with samsung users in this situation.

  2. emitters ARE enough for the WT (and flow rate) being used. HP runs steady. But house warms up (because you can’t get the HP’s output low enough to match heat loss). thermostat gets satisfied. HP switches off. house cools. thermostat is not satisfied. HP switches back on.

you’ve got the first one. you want the second one - cycle times there will be long.

as per matt, Higher WT might improve it because emitter output will be higher. but obviously costs you more. more / bigger radiators is the answer. Plus, work on your flow rate issue. Something must be slowing it down.

your e-boiler will either modulate lower or not care about short-cycling I guess…

147

Many thanks for this hint. I will try this. My flow is constant at the moment because installers didn’t connect PWM cable. So it’s running at max. which is up to 16 l/m. My radiators are just simple K1 so heat exchange won’t be great. I guess at this temp the flow will be too high for them. I don’t know.

Do you think for my radiators and flow dT = 10 would be better? Now I have set dt = 5. It worked good with this flow at 0C but at +5 it’s horrible. Could be that as Sarah said I have something wrong is software configuration.

In your system, it is stable also in higher outside temps ? I believe DAIKIN can go much lower than this crap. Really they sell it as 8KW and they restrict the performance in the software instead of installing compressor with lower power. Idiots. I would never buy this if I knew this but they states only max. power everywhere :frowning: Now it’s to late and need to deal with it somehow.

Do you think it is possible to set it in a way that it simply work by the thermostat? It turns off if temperature reaches a set value and then start when it decrease 1 degree bellow. I guess without external thermostat this is not possible or ? But then the HP becomes dummy as hell lol.

148

I dont think you’ll have any chance getting this thing stable at DT10. the most it allows you to configure is DT7 , from memory. also being able to actually control DT from the HP, l depends on having a PWM pump!

149

Exactly. Definitely it’s the first case, I just was not aware that the difference of just 5 degrees will have so brutal impact.

Yes, boiler has minimum power of 2KW but there it doesn’t matter because it just disconnect the spiral and it was 0 so there I didn’t care. But here 7/3 is horrible.

I will try matt advice, cross the fingers :slight_smile:

I just don’t understand this thermostat satisfaction. My issue is I’ve set the desired indoor temperature nowhere. It’s just displayed on the display but I can’t change it. This is what I don’t understand.

150

Yeah, I have PWM pump, problem is they did not install the PWM cable so it does not work. I’ve already ordered one so hope it will help a bit. Then I could try 7 and see if it help…

But if I set higher WT it will be more warmer indoors or ? This is a vicious circle :slight_smile:

151

Hi Michal,

I have almost exactly the same problem as you.

My 9kW Daikin goes down to 900w and about 4,000w of heat.

I need only just over 4,000w of heat at -2c outside.

With my old radiators I needed to run at about 42c to be stable at 10lpm flow rate.

Now I have much bigger radiators and I can run at 33c when it is -4c outside with 23c inside.

At over +5c outside I have problems but my heat pumps still runs all day with no cycling due to returning water temperature too high.

I would turn your flow up to 40c and your flow rate down to 10lpm if possible and see what happens.

From what you say, I would guess your radiators are way too small.

But if you want and can do it, give my idea a go and see what happens.

My 9kW is built the same as yours, compressor from a 16kW heat pump, it is useless in my house and will be swapped soon for the 8kW version.

But I have been through the nightmare you are having and still have it although I never had short cycling like this.

You need to run a high enough flow temperature and low enough flow rate for your radiators to give up the heat, then I am sure the short cycling will be gone.

Then you only have the excess heat to deal with and ultimately the radiator changes if you desire.

I think your Samsung is better at running in short periods than my Daikin.

What you lose now in efficiency though, you get back when it is colder. I think most heat pumps are a compromise at times.

152

Yes it will be warmer.

But it will always be warmer whatever you do as your heat pump puts out more heat at the minimum than you need to maintain the temperature in the house.

Hopefully you will be able to run it on a room thermostat so that it is on for a while, then off and so on.

You will have to put heat in with chunks, you won’t be able to run low and slow if that is as low as it will go.

I have this too, either run cooler at poor COP, shorter heating periods to control room temperature or run continuously and open windows.

Not great choices but if you are limited by electrical input that is what it is.

I know only too well!

153

@matt-drummer, @Ian_Calderbank

Guys, I think there must be some other problem. I was just looking at self-test mode where

Water Inlet Temp: 32C
Water Outlet Temp: 37C

This was fluctuating between 36-7 and then out of the sudden the pump turned off and showed following:

Water Inlet Temp: 32C
Water Outlet Temp: 34C

I would expect to see raising of inlet temp to 33,34 and then eventually close but this was not the case! What’s going on here ? Why it suddenly stopped ?

154

ok we haven’t been into this yet on your system. Photo your controller please, need to understand what mode you are running in.

do you have any 3rd party thermostat?

155

My heat pump is running at a dT of 6.3c at 10lpm and putting out 4,800w of heat

I would think if you can get 10lpm flow rate and a dT of 5c you will put out the 4,000w that your heat pump wants to deliver.

The flow rate is too high.

If you can’t get a dT of 5c at your flow temperature then you need to increase it.

It is simple mathematics.

I don’t think your radiators can keep a dT of 5c at 16lpm flow rate from what you are saying.

That is why your heat pump is shutting down, the returning water is too hot as the radiators haven’t cooled it down enough by delivering the heat to your house. They can’t do it at that flow temperature and flow rate.

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156

Wow, seems very similar to my case. Damn, I hate those installers have no idea how these things works and they only take money. Knowing this before I would buy a smaller unit because here we have max -10 or -15C only few days a year.

So can you tell me, you run at 42C at 10lpm at which outdoor and indoor temperature ? What was your heating curve ?

Jesus replacing all the radiators would cost lot of money damn. I can run 40C until -5 to maintain 22 but I guess I will start heating to 23C lol. In any case if they can maintain at this temeprature it’s either they are not that small or I have a good insulation lol. But the fact is that I run my pump at max 16l/m now no matter if there is -10 or +5C so while this was good when there was 0 and lower seems it’s not good at +5. I definitely need PWM so it can lower the flow as low as 7l/m!

I will definitely try your idea to lower the flow speed and increase temp of water by 2C.

You are going to but a new HP ? How old is your Daikin ? Did you already chosen the model ? In 15 year I plan to replace this one as well lol :slight_smile:

If there are not this cycling then I would be happy with that! But I don’t understand that you don’t have any short cycle ? How does it work then ? e.g if there is +10C ? How it can work without short cycling if minimum heat output is around 4KW ???

UPDATE: OK, I;ve changed the flow to 9.6 l/m. Let’s see if there is any difference!

157

Michal, don’t panic!

  1. There is plenty of experience on thus discussion group that Samsung have not properly implemented PWM outputs for circulating pump control on their MIM controllers, so it doesn’t make much difference if you set it up (mine is fixed speed and I have no problems…)
  2. Your Tw1/Tw2 observations are simply your ASHP switching itself off (even at minimum compressor speed of 50% the heat demand was met, so it had no option…).
  3. If your roomstat sends “room temp nearly satisfied” signals to the MIM more than than ~3 times per hour the MIM controller algorithm starts cycling the ASHP, Set the roomstat to <= 4 pulses/hr to the MIM.
    Sarah
158

by room stat do you mean the samsung controller stat? where’s that 4/hr setting?

159

Hi Michal,

My heat pump doesn’t short cycle because my radiators can deliver the heat produced, the returning water is always cool enough not to shut the heat pump down.

It is quite simple, the heat pump just produces hot water, what comes back needs to be cool enough by a set amount, once the water returning to the heat pump is similar in temperature to what it left at there is nowhere for the heat to go so the heat pump must stop until everything cools down.

A lower flow rate will allow your radiators to deliver more heat but you have to have the returning water cooler.

Radiator output drops massively the closer the mean flow temperature gets to the room temperature.

If your radiators cannot maintain a dT of around 5c at a flow rate of 10lpm then you will not deliver 4kW of heat and the returning water temperature will rise.

Once you reach a certain point all you can do to maintain the dT of 5c that you want is to increase the flow temperature, that increases the output of the radiators and the heat can be delivered.

A 1,000w radiator puts out 1,000w at a dt of 50c but only 120w at a dt of 10c. This same radiator would put out 300w at a dt of 20c

By trying to run water through your radiators at 35c you are severely restricting their ability to deliver the heat produced by the heat pump.

You need to assess your radiator sizes in relation to the heat loss of each room and replace them if they are not enough to run at 35c or less.

Otherwise you need to run at a higher flow temperature.

160

Hi Ian,
I meant our 3rd party roomstat, not the MIM roomstat. My Honeywell roomstat had internal settings (default = 6 cycles per hour which was OK for our gas boiler), and this confused the Samsung MIM so I changed it to 4 cycles per hour and that fixed things.
Sarah