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Hi all,
I wonder if anyone can help with this issue.
I have a Samsung gen6 ASHP (12kW) with a pre-plumbed Joule Kodiak DHW cylinder. It comes pre-installed with two Wilo pumps, fitted in series on the primary flow and return.
I run the DHW on a timed schedule once per day, normally timed to run in the afternoon when warmest and cheapest on Octopus Agile.
If the system hasn’t run for 24h, the pumps automatically kick in and run for 5mins, circulating water in the DHW tank circuit. For example, if I run the DHW cycle from 2:00-2:30pm one day, and schedule it for 3:00-3:30pm the following day, the pumps will automatically run for 5 mins at 2:30pm the next day, exactly 24h after last running.
This is an issue for me, as I have a 50L volumiser tank in the primary return, and running of the pumps circulates this now cold(er) water and draws heat from the DHW tank. This means I have no choice but to run the DHW every day, even if we may otherwise not need too. Heating the tank hotter and stretching out DHW cycles to every 36h is also not possible.
My question is can anyone explain why the pumps run every 24h for 5 mins, and is there a setting in the Samsung controller to control or disable this behaviour? I have been through the settings and manual in detail and cannot find any mention of this type of behaviour. Any Samsung experts able to advise?

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This is a new one on me, but you could rule out a quirky Disinfection effect by switching it off (FSV #3041 = 0) for 24 hours to see if the problem persists. Similarly, you could try switching the immersion heater off (FSV #3031 = 0), and checking that you don’t have Forced switched on (FSV #3051 = 0).
Sarah

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I have a Gen6 but no pre-plumbed tank. This is a pump anti-seize feature. However, on mine it only runs if there has been no pump activity in the last 24hrs. I do not use the heat pump for DHW, so there would be long periods in the summer where the pump was not used and could potentially seize.

I do not believe so. I contacted Samsung support last year about this and the frost protection system that does a similar thing. If the outside temperature falls below a certain value, it then periodically turns the primary pump(s) on (every 15mins, I seem to remember) to prevent the outside unit from freezing. I have glycol in that part of the system so that is unnecessary, but according to UK Samsung support, you can’t turn it off. Of course, a firmware upgrade may have changed this in the interim.

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@toadhall thank you, thank makes sense. It has indeed been running the pumps after exactly 24h of inactivity.
Now the heating season is starting, I will check to see if it continues, or if the heating running prevents it from happening, as the pumps should never go more than 24h idle.
We too have glycol to prevent freezing - I really hope the pumps don’t run every 15mins for antifreeze during winter, as if the 3-way valve is set to DHW position, it will be constantly drawing heat from my DHW tank.
The above has just prompted a thought - I’m sure I’ve seen a setting in the Samsung controller for the default position of the 3-way valve (FSV #3071), and I have it set to DHW. I wonder if changing this would prevent circulation in the DHW circuit which would alleviate the DHW issue (I don’t care if the pumps circulate around the heating circuit every 24h in summer)

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I would definitely recommend changing that setting to default to heating, not DHW. My NIBE system always puts the diverter valve back to ‘heating’ as soon as it has finished a DHW run, and I’ve never spotted any option to change that behaviour. It’s a good way to get some benefit from the residual heat in the system, at the end of a DHW run, even if there’s no ‘call for heat’.

Is your volumiser tank part of the DHW circuit, not just the heating circuit, by virtue of being plumbed into the shared return? That would seem odd. Normally they’re purely on the heating circuit, so they hold water at ‘heating’ temperature, not ‘DHW’ temperature.

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@dMb Thanks David - I will try changing the default setting for the 3-way valve now.

Yes, unfortunately the volumiser is fitted on the primary side return pipework, so affects both DHW and heating circuits. I agree it is not ideal, but it’s what we have. In the summer when heating DHW only, it’s just a waste of heat, but at least in the winter it can be circulated into the radiators following the DHW run.

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The “run-pump-once-every-24h” is also something I encounter on my Vaillant, but the pump only runs for about 10s, which seems sufficient if the purpose is just to prevent the pump from blocking.

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I’ve checked FSV setting #3071, and it was already set to ‘room’ rather than ‘tank’ (which is the default setting), so does not seem to affect the position of the 3-way valve during any pump anti-seizure run.
@Andre_K I agree, running for 5mins does seem excessive.

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It looks like it is a bit more intelligent than just blindly running every 15 mins. Today outside temperature is 2.5degC. The antifreeze cycle came on when the return/flow temperature had dropped to 5degC. The return/flow temperature went up to 49degC (because LPG boiler had been running) and it hasn’t done another antifreeze cycle for several hours yet. I suspect it will not do another one until the return/flow drops to 5degC again.

The 15 mins between antifreeze cycles I saw was in the middle of a cold night when the internal water temperatures were 18degC, so it wouldn’t take long for the return/flow temperatures at the heat pump to fall to 5degC.

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I have a Gen6 but no pre-plumbed tank. This is a pump anti-seize feature. However, on mine it only runs if there has been no pump activity in the last 24hrs. I do not use the heat pump for DHW, so there would be long periods in the summer where the pump was not used and could potentially seize.

I can confirm today that the pumps are still running every 24h after the last DHW cycle, even though they have been running extensively during that 24h period for the heating. This has to be a Samsung setting, but I can’t see anything in the field settings where I can disable or alter this behaviour.
The night before last I ran the DHW cycle at 3:30-4:00am as Agile prices were very cheap. We then didn’t intend to run DHW again until this afternoon, but woke this morning to find the DHW tank temp had dropped to 25C as the pumps had run for 5mins at 4am and effectively cooled the DHW tank. The pumps had been running during the 24h period for heating, so this behaviour seems to be linked only to the DHW and is not affected or altered by the heating.

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Hi, I also have a Samsung Gen6 heat pump and 200l Joule tank. I have also observed this 5 min cycle (when both heating and hot water have been timed to OFF), and if it happens an hour after the tank has been heated, as it did today, I lose 5C to 7C, or more, which is frustrating. At the same time, the flow temperature increases, even though the heat-pump is off. I am fairly certain the radiator circuit valve is closed, and certain the DHW vale is open, as I managed to get a hand on each one and also heard only the DHW valve actuate. This is entirely different to the cycles that occur if the system detects a low flow temperature, and also different to defrost cycles that occur either during DHW or Heating. I also believe if it is in a DHW cycle and needs to defrost, it takes the heat from the water tank, but if in a heating cycle, it takes it from the radiator circuit.
I think this cycle occurs every 24 hours regardless of when the pump was last run, which is not sensible. In this case, it was heating the house just one hour prior. Is this a bug in the Samsung software or just a poor design? And what sets the start of this 24 hour period? Is it when the system first powers up? If so, I might try to move this 5min cycle to a time when I know the DHW is already on by powering down and powering up the whole system at that time, and see if this behaviour stops.
Has anyone contacted Samsung for technical support on this problem?

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Hi Peter and welcome to the community :slightly_smiling_face:

I’ve found that Nick Kirwan at the UK Helpdesk (tech.aircon@samsung.uk) has been helpful (as far as “HQ” allow him to be - Samsung are quite protective of their technical assets aka competitive advantage…).

As for the hourly frost protection, he has explained that (my emphasis):
“This is the anti-freeze logic, when ambient is below 3C and the system has been idle for 60 mins the primary pump will run for 5 mins with the DHW valve energised to ensure return temperature is above 6C. This will happen every hour these conditions are met. This logic is fixed and cannot be turned off.”
@Michal_S suspects that the 3degC is more like 5degC.
I too have glycol, but you can’t tell this to the controller, so it does this frost protection cycle anyway… :upside_down_face:
He has also confirmed that during a defrost cycle, heat is taken from whichever system was in use at the time of defrost demand (DHW tank or space heating circuit).

There have been other observations on this forum regarding the “circulating pump exercising” cycle - some say every 3h, some say every 24h - I’ve not seen it myself (I don’t continuously monitor), but I suggest you fire off the question to Helpdesk to try to get a definitive answer…

(There is also anectodal evidence that a DHW cycle actually provokes a defrost cycle under some circumstances - looking into this is one of my next projects now that I can monitor my outdoor unit in comfort.)

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It is 3degC, this graph shows it rather well (around 9 and 10 am)

https://emoncms.org/app/view?name=SamsungHeatpump&readkey=88a6c522550d5fd6ffece80a646b4952&mode=power&start=1736087040&end=1736173440

Caveat here is that I have moved the outside temperature sensor to a more sensible position. The standard place behind the coil is theoretically a good place (lots of return air flow, so should be a good measurement of ambient conditions). Unfortunalely it has several drawbacks

  • It is very close to the coil. I noticed when the heat-pump was running it would drop by a degree or two. Could have been picking up recirculating air but it is installed according to the manufacturers clearances.
  • When it rains the measured temperature drops, since it is exposed. My other external sensors also show a drop in air temperature when raining, but only about half the Samsung drop. The other external sensors are in Stevenson screens, so I tend to believe them.

The Samsung sensor is now in a Stevenson screen (well, conduit box) under the eaves on a north facing wall and it no longer exhibits any weirdness.

It’s every 24h, see

https://emoncms.org/app/view?name=SamsungHeatpump&readkey=88a6c522550d5fd6ffece80a646b4952&mode=power&start=1722423600&end=1722769200

This is from the summer.The large spikes are the HEMs exercising the heat-pump if it hasn’t run for 3 days (best to find out it’s broken before you actually need it). The small spikes you can see on the 1st and 2nd of August are the anti-seize pump cycle. They happen exactly 24h after the heat-pump is exercised OR the last anti-seize cycle was run.

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Hi Sarah, you are a star. This is exactly what I have observed now you have explained the conditions.
I currently optimise my heat pump operation for minimal cost, using the Octopus Cosy tariff. 3 low cost sessions each 24 hours, totalling 8 hours, plus any standard rate operating to maintain the house temperature, and DHW only in the low cost sessions. The downside is I switch off or setback the heatpump between 4pm and 7pm. It is during this time AND when the ambient is below 3-5C, that the hourly anti-freeze cycles depletes the DHW. I observed it declining from 50C to 18C during 3 antifreeze cycles :(.
I have supplemental heating in the cold spells (wood burning stove) and so there is always lots of thermal mass in the heating circuit. So really frustrating that the defrost cycles don’t take the energy from the heating circuit rather than the DHW.
There is a Field Value setting #3071 which I thought might have been used to decide if the DHW or Heating circuit could be used for this purpose (described as position of 3 way valve for DHW) but this must have another purpose.
It’s a pity Samsung don’t offer Field Value settings to select the heat source for the antifreeze cycles, or their interval, or their duration (5 mins!), for those like me that have around 15% glycol in their system. One for the future, perhaps.
I suspect the Samsung designers believed the heat pump would be running heating and DHW 24/7. 2/3rds of my heating energy consumed by the heatpump is at the off-peak cost of £0.1231 per kW, at a SCOP around 3.8. That makes it way cheaper than gas. I am sure I could get this SCOP to 4 if I didn’t have to reheat the DHW tank from 18C to 50C every evening during the winter.

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PS I have also seen the 24 hour cycle occurring, usually in the summer, and this too can reduce the temperature of the DHW tank, but it does not reduce it too much and doesn’t take much energy to restore it. So this will have minimal impact on the SCOP.

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Hi everyone,

Thank you all for your responses to this thread - I have been reading them with much interest and really appreciate everyone’s contribution. Unfortunately I’ve yet to be able to figure out how to quote others to reply directly to their points raised, so make my comments generically below.

I now have a better understanding of the different issues due to the contributions above, and would break them down into 2 areas:

  1. The anti-seize cycle that runs after 24h of inactivity to prevent the pumps from seizing, and mostly affects in summertime.
  2. The ‘Freezing Control’ cycle that runs during cold weather to prevent freezing of the outdoor unit.

Starting with (1) above, this occurs after 24h of pump inactivity and the pumps will cycle for 5 mins with the DHW valve open. This can cause issues in the summer if the DHW is not reheated every 24h, draining heat from the DHW tank. I was affected by this issue last summer as I was varying the time of the DHW reheat cycle to coincide with the cheapest 30min Agile pricing slot, so on some days the period between reheats would exceed 24h. As we have a 50L volumiser, this effectively transfers heat out of the DHW tank into the volumiser, reducing the water temperature.

I have found a manual workaround solution to (1), and that is to manually cycle the pumps every day, within the 24h period. To do this, I enter Self Test mode, open the DHW valve and turn the pump on. You only need to run the pump for a couple seconds before turning off again for the system to register pump activity and reset the 24h period, and manually running the pumps for a few seconds will not drain anywhere near the amount of heat from the system as running for 5 mins.

Regarding issue (2) above - I am in a near identical situation to @Peter_Reid. We too are currently on the Cosy tariff, and turn off the heating for the peak period between 4-7pm. I can confirm on my Samsung gen6 12kW unit, the ambient temp at which the Freezing Control kicks in is definitely 5C and below, not 3C as suggested above (I observed my system the other evening as the temperature dropped to 4.5C and the freezing control kicking in just over an hour after the heating was turned off). It’s actually worse for us as our external ambient temperature sensor reads around ~1C low, so it’s actually activating at ambient temps of around 6C and below (not 5C), and I have no way to recalibrate (that I know of).

I have not found a good workaround or solution yet to manage this situation. We typically reheat the DHW during the 1-4pm cheap slot and turn off the heat pump during the expensive 4-7pm slot. When we come to wash up after the evening meal, all the hot water is gone again which is a ludicrous situation. During the off period, I have tried putting the unit in Self Test mode, which prevents anything running, but it then throws an error code after an hour when the pumps cannot start (E911). I then exit Self Test mode at 7pm, clear the error and turn the heating back on, with DHW still intact. Sometimes the system ends up throwing multiple errors and the system locks up requiring a power off/on to restart the system. The other option is to just turn the whole system off at the wall during the period and back on again when ready to turn the heating back on. I would appreciate any thoughts if this type of power cycling of the indoor controller is doing any long term harm?

This issue also affects me overnight. Unless the weather is freezing cold, we also tend to turn the heating off overnight and reheat from cold the following morning which costs less than running constantly overnight. If it’s freezing, it’s not an issue as we’d run heating overnight, and if it’s mild (well above 5C) it’s not an issue as the Freezing Control won’t activate, but where it’s in the 3-6C range, it’s an issue and the DHW tank is stone cold by morning. Again, my solution at present is to just turn the whole system off at the wall overnight and back on in the morning.

I have tried to put the issue into financial perspective. I have casually observed that reheating the DHW from stone cold vs if that tank had normally cooled to mid 30’s C, probably costs an additional 1kWh for us. At Cosy cheap rate, this is maybe only costing us 12-15p per day, on a handful of days per year. So financially it’s not a disaster by any means. That said, it’s the inconvenience of not getting up to any hot water, and then we’d have to reheat it as standard rates which costs twice as much, or we end up boiling a kettle to wash up having just lost a cylinder of hot water that we’d only just reheated.

I just wish there were a way to override the controller to tell it to work how I want it to work, to suit our environment and needs. We have glycol, so the anti-freeze control for us is almost pointless and I’d welcome a setting to be able to adjust the activation temperature and/or disable it.

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Like this: Highlight the text you wish to quote by dragging your mouse. As you release the button, the options pop up. I clicked “Quote” and it opened the reply box and I started typing “Like this…”

image
image1078×223 54.9 KB

You can switch to another Topic in the top pane whilst still keeping the reply/contribution you’re typing in the bottom pane, and then quote again, still from the top pane, e.g.

Is this what you’re trying to achieve?

@Old_Scientist
Or this is what I sometimes do: start a new paragraph with an “@mention”. and start typing the user’s name. The system pops up a list of matching users for you to select from. It’s then clear who you’re addressing the next part to.

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Thanks @Robert.Wall - that’s a perfect explanation :slight_smile:

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