Samsung Mono HT Quiet & DHW max. temperature limited to 55C

Daikin do the same.

My 9kW was really a 16kW.

A nightmare as you know.

This 8kW is much better for me but still not fit and forget.

There’s a problem.

This is why I did not email when I was ill, it’s too complicated.

I installed radiators to deal with my 9kw, so I could lower flow temperature.

Now I have a smaller heat pump I need even lower flow temperatures.

Something like a Vaillant, no problem.

But this Daikin doesn’t like below 30c, a bit hotter when warmer.

So I have to run at 30c even though I could go lower with another brand of heat pump.

They don’t tell you, just like Samsung.

But I had no choice, my installer (the only one I could get) only supplied Daikin so that is what I have got, the smallest Daikin you can get.

Of course, they do 4kW and 6kW but they are just software limited 8kW units.

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Oh yes, sorry. I was thinking of Daikin who do the same.

Oh so also Daikin is doing this ? Insane…

Then you have to decide between real 8KW units where you can have problem with colder climates. I think in UK you will not have an issue but here in Winter temperature can get close to -10 to -15C and I guess 8KW would suffer badly and not sure if ii would be able to heat the place. 8KW is max. but until which temperature this is achievable ? 0C ? -5C ?

I think next time I will buy a pump I will ask manufacturer how low it can modulate :slight_smile:

Mitsubishi are allegedly doing it too…

https://community.openenergymonitor.org/t/monitoring-controlling-ecodan-via-cn105/24981/234

Can you detected when a cycle ends then remove the “call for heat” signal until 30 minute after the cycle started?

What do you mean exactly ?

The idea of forcing the heatpump to pause between cycles has come up a couple times.

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Hmm, actually I do this with thermostat. I’ve set hysteresis +/- 0.2C. So e.g. I’m running pump by weather curve but not less than 38C. So in case there is 10C outside and I have target temp set to 23C then thermostat command the pump to stop when indoor temp reach 23.2C with flow temp of 38C. Then it will start it when it decrease below 22.8. In warmer wetter the pump is off maybe for one or two hours so it’s pretty good. When I did not use thermostat it used water law and to achieve best efficiency the pump was cycling every few minutes like crazy. So maybe efficiency was a bit better but the components must suffered heavily.

So basically this is what you mean by pauses between cycles right ? Does this solution have some benefit over this one with thermostat ?

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Hi Michael,
Yes, if switching on the thermostat, then the hysterysis will cause a welcome pause. The problem is when the unit cycles off when stat is on. e.g. when the heat load is low and the heat pump drops to the minimum, but the flow temperure creeps up. The unit has to stop. The ecodan seems to start only 4 mins after stopping. I never did make a module to help with this. My idea was to have a pause depenent on outside temperature.

Hi John,

Yes, Samsung does the same. The warmer the weather the more cycling observed. With my system it was really unbearable. In the past I’ve shared this screen - 8 cycles per hour:

Absolute craziness. Of course combined weather law + thermostat did not work properly because the pump always turned heat since water temperature was too high to keep up with target so I had to switch to pure thermostat regulation. In that way the pump never turn off and tries to keep as lowest LWT as possible. Often this is inefficient because compressor and FAN are running an minimal speed. Water law tries to optimize this but not in a very nice way.

Pause based on external temperature is good idea if you don’t have any other choices but I’ve found this thermostat is pretty good. I think every pump offers this kind of control. In colder weather usually the pump is running 24/7 so thermostat will not kick in and when there is hotter it will turn off the pump. Once indoor drops by 0.4C it will start it again. I had maybe 3 or 4 cycles per day. Problem is that man users won’t notice this and it’s definitely not good for a pump.

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Isn’t that link talking about immersion style booster heaters? The only software limited Mitsubishi ASHPs are the R32 6kW and R290 5kW.

Quite a few Ecodans are limited versions of the same model, as discussed in this topic: Heat pump size as a soft setting

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With my own experience with R410 twin rotary compressor there is alot of oil in the refrigeration lines. There is no oil seperator installed in the unit and no oil injection at the suction line respectively.The oil seperation of the compressor itself is very poor. At high revs alot of oil is circulating in the system. I planned a full rebuild of my heatpump next summer and installation of oil separator to monitor the effect of oil sepration on the whole system and efficiency values. After two years of explotation of my Atlantic Fujitsu HP and alot of learning I can surely state that the refrigeration cycle in these small AC/HP systems is not well ingineered for heating purposes.

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