Samsung AHSP & DHW tank struggles

Hardware Heatpump
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1

Hi guys, can anyone please explain me how this exactly works because I’m at lost.

Thing is I’ve installed DHW tank recently. The target temperature is set to 50C but for unknown reason the pump heats water only to 46.x Celsius. Also it start to reheat when it drops exactly by 10C so at 40C.

I can’t get this what’s the logic behind it because obviously field settings are set differently.

I’m running DHW at eco mode so wonder if this could be reason so somehow field settings are ignored ? I don’t know but I have actually:

DHW Mode set to 1 (DHW on). I had also set to 2 (which is some kind of mode with hysteresis but I don’t understand the difference)

Max. temp 55C (Can’t get higher even though this is HT pump so theoretically it should go up to 70C because disinfection is running at this temp). However, I don’t know if disinfection work without immersion heater because I’m yet waiting for disinfection cycle.

Then there are STOP (2C) and START (5C) field settings. I kept default values but I have no idea what they are doing because the pump behaves differently.

This is the graph from last night.

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There was only one reheat lasting 22 minutes:

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So in terms of power and COP it looked like this. So I can see it wasted 1KW of energy unnecessarily…

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Can someone give me some idea how shall i setup this pump with DHW?

I guess it’s not possible to prevent these warming cycles during cold night if space heating is turned off (if you have idea let me know because without DHW connected it was stealing heat only from radiator circuit) but how to set a pump it will heat to 50C what I’ve set and then heat according fields settings.

I’ve assumed if I set 50C as target, Start to 5C Stop to 2C the behavior will be that the pump will start heat water when it drops to 45C and stops heating when it reaches 52C but maybe I’m reading this wrong?

Thanks for insights.

2

@Michal_S check FSV 3025 for maximum DHW run time to try and solve the 22min run time issue. I’d recommend setting this to 60-90 mins.

I’m not sure you can control where it pulls heat from for defrost. I’ve seen it do from CH and DHW. There is a priority setting somewhere, but I’m not sure what this does.

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Thanks for hint. I’ve already set it to 45 minutes. Also changed #1051 which is max temp you can set on roomstat controller to 70C. Now I can select DHW until 70C but without booster it works only up to 55C sadly. God a tip for overshoot from Sarah so I need to try it to see how high I can go with DHW temp.

For defrost it pulls the heat from the source which is currently active. Issue is at night where I usually turn off CH by thermostat so pump is not running. Then every hour or so pump opens 3-way valve, start the pump for 6 minutes an pull heat from DHW tank to reheat the lines. Can’t say I like this behavior, I would be more happy if it takes the heat from the space heating circuit as it was before I had DHW tank. So this is not really for a defrost but to keep the outdoor unit on temperature to prevent freezing if pump is not running. I guess there is no priority settings but maybe I’ve overlooked something.