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12kW Samsung gen 6 short cycling

Craig1980 · 2022-11-23T23:30:08Z

Good evening. Welcome to my life staring at my ASHP and scratching my head. I've had a Samsung gen 6 12kw ASHP fitted with all new pipework and rads on an eco4 grant so you can guess that I was just handed the room stats for each of the two zones and told to adjust with the stat.The system was set at 55 and no WC. No legionella either (although I've turned this off and will run manually as and when). The house is a medium 5 bed, cavity bead insulation, loft insulation and double glazing. It's a 60s house but modernised and well insulated for its age. It is in West Wales so fairly mild climate. I like to run the house at 18 degrees max so I've set the WC pretty low at 20 and -3, 20 and 31. I'm getting a good COP at around 3.7 although that has dropped to 3.4 today. Using around 16kw including water heating for up to an hour. Temp today is 8-9 degrees and the pump runs for around 7-8 mins, turns off for 18 seconds then runs again for 7-8 mins. It starts at 100w and peaks at 800w. House is sitting at around 19 degrees. Water law is set up on Floor, should it not be set on Fcu and rad? What diffeference would that make? External thermostat #1 and #2 and remote controller room temp are all set on "room temp on/off or WL interlink on/off (water pump 3)". Is that correct? My question is how can I stop the short cycling and how can I improve efficiency? Sorry for all the questions but I've driven myself mad staring at that screen. 🙈🤣

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Air Source Heat Pumps (ASHPs)

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Derek M

(@derek-m)

Illustrious Member Member

Joined: 6 years ago

Posts: 4425

22/02/2024 1:28 pm

Posted by: @craig1980

↑

A quick update on my system.

I'm running at a COP of around 3.3-3.4 at around 3 degrees outside temp including water heating for an hour at midnight. I'm still messing with settings so hopefully this will increase. Once the cold weather arrives the COP definitely drops.

LWT at around 28-29 degrees and WC is on.

Derek got to the bottom of the issue. I was running the WC settings incorrectly. There are 3 options which run the pump in different ways whilst WC is on and one of those tells the pumps to turn off after 7 mins then back on. That's why it was short cycling.

I still need to contact Samsung and I'll let them know about this thread. My Teva out sensor is showing -50 so I may need a new sensor there. I've checked the outside heat pump and it is all plugged in properly. I'll reply on here with any updates.

Craig (@craig1980) would you be kind enough to provide @iantelescope with details of the changes that you made to the controller settings to stop the short cycling.

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iantelescope

(@iantelescope)

Reputable Member Contributor

Joined: 4 years ago

Posts: 418

22/02/2024 3:10 pm

@derek-m

Hi Derek,

Many thanks for the data.

I have tried the Samsung Field bits 2091 Options 1 to 4 on several occasions.

I too found the field bit 2091 option 4 was suspiciously near to my original 8 minute Cycle time.

Samsung field bit 2091, Water Pump 3 subroutine :

1) Delay for 3 minutes

2) OFF for 7 minutes .

3) ON for 3 minutes.

4) OFF for 7 minutes.

However, I, and the French Samsung Engineer tried all of these settings , multiple times, without any great effect.

The pulsing briefly increases the water temperature, and cycle time during the water cycle .

I Do currently use Water Pump 3 given the 2 C thermostat Hysteresis and the slight resultingincrease in cycle time caused by the extra, mid cycle, Motor pulse.

I have , however tried setting Field bit 2091 , Water Pump 2 subroutine again. given that many other parameters, and settings have changed in the interim.

Samsung field bit 2091, Water Pump 2 subroutine has however a 1 C Hysteresis.

Many thanks to you and Craig.

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