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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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Derek M

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25/11/2022 9:15 pm

I'm actually genuinely shocked that the Samsung monobloc isn't really very monobloc at all, and needs and external pump and flow switch. It makes me feel much more happy with my decision to go for an off-brand manufacturer for my own system (I went for a Cool Energy, made by SPRSUN in PRC, built on a complete Carel commercial refrigeration platform of parts)...

It is just good business for Samsung, if they don't fit an internal water pump, they can either reduce the price or make more profit. 😋

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Derek M

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25/11/2022 9:18 pm

Posted by: @craig1980

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@hughf so, does this mean that had a different pump been connected we would be able to adjust pump speed? Thanks

What water pump do you have installed? It may have the capability for PWM control, just not the required cable and settings.

This post was modified 3 years ago by Derek M

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Craig1980

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Topic starter 25/11/2022 9:48 pm

@derek-m one of these.

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Derek M

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25/11/2022 10:37 pm

Posted by: @craig1980

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@derek-m one of these.

It would appear that it is not capable of accepting a PWM input signal.

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Craig1980

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Topic starter 25/11/2022 10:45 pm

@derek-m shame. I wonder if this is cost cutting on their behalf or they are just not aware a better pump can be integrated. 🤔

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Derek M

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26/11/2022 12:45 am

Posted by: @craig1980

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@derek-m shame. I wonder if this is cost cutting on their behalf or they are just not aware a better pump can be integrated. 🤔

Probably the former.

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HughF

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26/11/2022 8:30 am

Posted by: @craig1980

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@derek-m shame. I wonder if this is cost cutting on their behalf or they are just not aware a better pump can be integrated. 🤔

Who did your install? If it was supplied through freedom then they would have followed the manual written at freedom, and that specifically uses fixed speed pumps on primary/secondary and an external on/off stat.

Off grid on the isle of purbeck
2.4kW solar, 15kWh Seplos Mason, Outback power systems 3kW inverter/charger, solid fuel heating with air/air for shoulder months, 10 acres of heathland/woods.

My wife’s house: 1946 3 bed end of terrace in Somerset, ASHP with rads + UFH, triple glazed, retrofit IWI in troublesome rooms, small rear extension.

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Transparent

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26/11/2022 10:58 am

Just a reminder that on the previous page we've concluded that you can't just exchange the pump for one that accepts a variable PWM signal. You'd also need a matching control output from the Samsung unit to tell it what speed to run at.

Unless someone (the installers?) identifies that the Samsung ASHP system can deliver such a signal, then let's ignore that strategy for the moment.

This part of the discussion has still been immensely valuable. It will serve to better-inform others contemplating a Samsung unit in future.

Posted by: @craig1980

↑

Just as an update to this post yesterday's COP including water heating was very nearly 4.

That's excellent for an ASHP in 2022. 😎

Save energy... recycle electrons!

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Craig1980

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Topic starter 26/11/2022 11:07 am

@hughf consumer energy solutions

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Craig1980

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Topic starter 26/11/2022 11:10 am

@transparent agreed, it's not something I'd be changing anyway, it's just nice to know my options.

I'm happy with the COP but still slightly concerned by short cycling. COP down to 3.4 yesterday with no changes carried out by me. Weather seemed similar but could've been colder I suppose. It did shut off for a while as due to solar gain house temp exceeded 21 which is what room stats are set to. What should I do in that situation? Thanks

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Transparent

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26/11/2022 11:28 am

Posted by: @craig1980

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It did shut off for a while as due to solar gain house temp exceeded 21 which is what room stats are set to. What should I do in that situation?

Change into shorts and a tee-shirt 😎

Or... more seriously, I have a Mechanical Ventilation with Heat Recovery (MVHR) system in my loft which takes the hot/sticky air from rooms such as kitchen and bathrooms. It extracts the heat, which gets used to warm a fresh-air intake. That gets fed to rooms on the colder, north-side of the house.

It all rather depends on...

... how enterprising you want to be in exploring lots of energy-related technology

... and how much time I have to start a new topic on installing MVHR.

This post was modified 3 years ago by Transparent

Save energy... recycle electrons!

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Derek M

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26/11/2022 1:51 pm

Posted by: @transparent

↑

Just a reminder that on the previous page we've concluded that you can't just exchange the pump for one that accepts a variable PWM signal. You'd also need a matching control output from the Samsung unit to tell it what speed to run at.

Unless someone (the installers?) identifies that the Samsung ASHP system can deliver such a signal, then let's ignore that strategy for the moment.

This part of the discussion has still been immensely valuable. It will serve to better-inform others contemplating a Samsung unit in future.

Posted by: @craig1980

↑

Just as an update to this post yesterday's COP including water heating was very nearly 4.

That's excellent for an ASHP in 2022. 😎

I had a quick look through the Samsung manual, to which HughF posted a link previously, and if my eyes did not deceive me, it clearly stated that the primary water pump should be controlled by a PWM signal from the controller.

So either Freedom have ignored the Samsung instruction, or the controller installed is not capable of outputting a PWM signal. 🙄

Graig, could you post model details from the nameplates for the heat pump, controller and any other equipment installed within your system.

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