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?
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
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.
@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)
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.
@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.
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.
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.
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.
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.