# Problematic Samsung Gen6 Defrost Cycle **URL:** \ **Category:** Heatpump\ **Created:** [10 December 2024 12:27 UTC](https://community.openenergymonitor.org/t/problematic-samsung-gen6-defrost-cycle/27374 "2024-12-10T12:27:30Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![CoP](https://community.openenergymonitor.org/letter_avatar_proxy/v4/letter/c/91b2a8/32.png) [@CoP](https://community.openenergymonitor.org/u/CoP)\ **Post date:** [10 December 2024 12:27 UTC](https://community.openenergymonitor.org/t/problematic-samsung-gen6-defrost-cycle/27374/1 "2024-12-10T12:27:30Z")
I use cheap overnight electricity to heat my DHW. I have a good size hot water tank and a very large buffer (750l or so). Normally this works well, but when it is cool, the defrost cycle switches the divert valve to take from the DHW, reducing the DHW temperature about a degree each time. I rapidly have no hot water! Essentially I do not want it to turn the divert valve, and instead to take from the buffer. But there is no obvious option to do this. I have a modbus unit that I haven’t connected yet. I was wondering if there was any way of overriding the divert value? Preferably an elegant way rather than a bodge! ---
**Author:** ![SarahH](https://community.openenergymonitor.org/user_avatar/community.openenergymonitor.org/sarahh/32/27116_2.png) [@SarahH](https://community.openenergymonitor.org/u/SarahH)\ **Post date:** [11 December 2024 11:29 UTC](https://community.openenergymonitor.org/t/problematic-samsung-gen6-defrost-cycle/27374/2 "2024-12-11T11:29:46Z")
Hi @CoP, Your observation is somewhat at odds with the info I obtained from UK Tech Helpline. They told me that the defrost heat source was whichever system was in use at the time of the defrost demand (i.e. DHW tank during a hot water demand, buffer tank otherwise). In other words, a defrost demand does **not** flip the diverter valve, so as long as DHW isn’t enabled when the defrost is required, then heat should only be taken from the buffer/volumiser. I suggest that you contact the helpline ([tech.aircon@samsung.com](mailto:tech.aircon@samsung.com)) - I may have misinterpreted their info, but otherwise is it possible that there is a fault in your setup? [There is a setting on the Outdoor Unit panel - Defrost Operation K-buttons = 010x where x = 0 (basic) or 1 (option), but there is no information in the Installers Guide (p122) on what “option” does, so I’d regard this as a long shot…] ---
**Author:** ![CoP](https://community.openenergymonitor.org/letter_avatar_proxy/v4/letter/c/91b2a8/32.png) [@CoP](https://community.openenergymonitor.org/u/CoP)\ **Post date:** [11 December 2024 12:02 UTC](https://community.openenergymonitor.org/t/problematic-samsung-gen6-defrost-cycle/27374/3 "2024-12-11T12:02:35Z")
Thanks @SarahH ! I don’t think the information from the technical helpline can be right. I’m almost certain that the defrost cycle always switches the DHW valve and takes from the DHW, but I will certainly double check if there is a way around this. ---
**Author:** ![SarahH](https://community.openenergymonitor.org/user_avatar/community.openenergymonitor.org/sarahh/32/27116_2.png) [@SarahH](https://community.openenergymonitor.org/u/SarahH)\ **Post date:** [11 December 2024 12:48 UTC](https://community.openenergymonitor.org/t/problematic-samsung-gen6-defrost-cycle/27374/4 "2024-12-11T12:48:41Z")
I guess one easy way to check would be to completely disable DHW using the Schedule option on the remote controller one really cold night (when a defrost is likely), and see whether the DHW tank temperature has fallen noticeably afterwards. (It could be - if you have DHW heating permanently enabled on its programmer - that the cylstat just happened to be demanding DHW heating at the moment that a defrost was also demanded.) ---
**Author:** ![Timbones](https://community.openenergymonitor.org/user_avatar/community.openenergymonitor.org/timbones/32/20308_2.png) [@Timbones](https://community.openenergymonitor.org/u/Timbones)\ **Post date:** [22 December 2024 15:55 UTC](https://community.openenergymonitor.org/t/problematic-samsung-gen6-defrost-cycle/27374/5 "2024-12-22T15:55:04Z")
Related topics about this same issue: > [@Samsung R32 ASHPs - when is a defrost not a defrost?](https://community.openenergymonitor.org/t/samsung-r32-ashps-when-is-a-defrost-not-a-defrost/27553): > > I wonder whether we Samsung users have been conflating two controller algorithms… Samsung tell us that real defrosts are subject to the following defrost strategy: You will see that this implies that a defrost cycle starts when the R32 temperature leaving the EEV is at or below -6degC, and stops when various other parameters combine/apply. This starts the compressor, … > [@Daikin: Defrost cycle pulled heat from DHW](https://community.openenergymonitor.org/t/daikin-defrost-cycle-pulled-heat-from-dhw/26696): > > Here’s an odd one. I have dhw set on “comfort” from 3am to 7am to take advantage of off peak tariffs. This morning was my first proper defrost since install in April last year and it appears to have opened the three port valve to take heat from the dhw. Tank temperature dropped from 50 to 44 degrees. I’ve never seen this before, any ideas what’s going on here? Link to my emoncms if you want to look in detail: [https://myheatpump.uk/app/v…](https://myheatpump.uk/app/view?name=DaikinEDLA08E2V3&readkey=4b67a63aec8b77bd655bab9680b01203) ---
**Author:** ![CoP](https://community.openenergymonitor.org/letter_avatar_proxy/v4/letter/c/91b2a8/32.png) [@CoP](https://community.openenergymonitor.org/u/CoP)\ **Post date:** [12 July 2025 22:31 UTC](https://community.openenergymonitor.org/t/problematic-samsung-gen6-defrost-cycle/27374/6 "2025-07-12T22:31:03Z")
I’ve had a careful look at this again, and you’re absolutely right. The defrost takes from whatever source the ASHP has most recently been heating. See attached. ![Screenshot 2025-07-12 at 23.23.00](https://community.openenergymonitor.org/uploads/default/original/3X/4/7/47e2ef886dc7ef8b90dbb46dbec101b7d38dc58a.png) What seems to be happening is when the outside temperature is around zero and then the defrost cycle is taking from the DHW. I’m assuming this is the default. Some time ago Samsung technical suggested building in a 5-minute delay to the relay so it misses the signal. ---
**Author:** ![CoP](https://community.openenergymonitor.org/letter_avatar_proxy/v4/letter/c/91b2a8/32.png) [@CoP](https://community.openenergymonitor.org/u/CoP)\ **Post date:** [30 August 2025 20:01 UTC](https://community.openenergymonitor.org/t/problematic-samsung-gen6-defrost-cycle/27374/7 "2025-08-30T20:01:52Z")
I’ve decided on a better solution to address this than the one suggested by Samsung. The problem is when the system runs to prevent freezing. This normally happens during the period during higher rate electricity when the ASHP is set to remain off. If I add a timer to cut the signal to the actuators doing this time, it ought to prevent the unit drawing on the costly DHW.