I’m still improving my pipework and recently installed an additional circulating pump to improve the flow towards the 26lpm that seems to be the norm/required. Also learning more about understanding the dashboard results.
Are these defrost cycles normal and are the parameters viewable/adjustable anywhere?
Samsung doesn’t have any configurable options with regard to defrost.
It’s a bit surprising to see defrost cycles every 30min when the temperature is about 7.5C. My Gen6 Samsung doesn’t start defrosting until it gets down to about 1-2C, but this does depend on other factors like humidity etc.
I’ve had 2 previous heat pumps in the same location and neither of these did any defrosting until the temp dropped towards 0c so it does seem excessive to me and looks to be interrupting the cycle.
Defrost does appear in the front of the manual with dil switch options but cant find any further reference and we have never touched these switches so far.
Last night it was doing a defrost cycle on a regular basis, today not so?
Here’s what I got from Samsung UK Tech Helpline when I asked for the Gen 6 defrost strategy. I can’t say I understand it, and they could offer me no further detail, but it looks like defrost doesn’t kick in until the R32 entering the evaporator hits -6degC???
Any help with interpretation gladly received…
The Gen 7 systems listed on HPM don’t seem to defrost nearly this much, it might be interesting for your to compare the data yourself:
https://heatpumpmonitor.org/?filter=samsung+gen+7&period=all&minDays=0
Don’t think they are defrosts mine looks similar when its cycling couple of times an hour when its above 10deg
These are defrosts (outside temp was around zero)
Thanks for the info. From the data from Sarah looks like the parameters for a defrost cycle are a lot below the event I am experiencing.
So what is it? Cooler today but doing less of it what ever it is!
These are defiantly defrost cycles, the flow temp dips below return temp and there’s negative heat. They are small defrosts, this must be a relatively small heat pump with a small evaporator. It doesn’t take much energy to defrost compared to larger double fan units.
Definitly some sort of a defrost but when I stand beside the HP when its doing it just seems to stop for a while then start again.
My first hp was an 8kw and it had to run frozen before it would do anything and it was quite spectacular as was the 2nd hp.
Seems to produce a lot of condensation from the drain more than the others but the puzzle is others similar dont do it as Glyn points out.
Got this reply below from Samsung technical but doesnt answer anything at least not to me
The defrosting of your unit is governed by a lot of factors including outside temp, flow rates, what is open on the circuit at a particular time and water volume. Without knowing these its hard to judge if your unit is running correct for the environment or is defrosting more/less than expected.
Is the system in an actual defrost or just going thermo off?
BTW I did send screenshots from the monitor dasboard
I’ve looked back and mine always looks like this when a cycle ends even with temps above 15deg!
Surly it can’t be a defrost?
Its an 8kw gen7 Samsung so not the smallest or old.
EDIT
I’ve looked at a couple of other gen7s and they seem to do the same, flow temp dips below return briefly at the end of a cycle
Hi Ian,
The temperature reversal is due to flash cooling of refrigerant in the condenser when the circuit is depressurised (the controller always opens the compressor recycle valve immediately the compressor stops, so as to prevent reverse flow through it). There’s only a litre or so in the condenser, so it doesn’t take long to re-evaporate the residual liquid, after which normal service is resumed (LWT>RWT).
Sarah
Thanks, that explains it.
Yes good explanation but some seem worse than others from when I looked.
Samsung technical seem to have misread the dashboard graph I sent as have interpreted the flow as 37lpm rather than the 20 or so actual and are sending a replacement sensor.
Sarah. Can I sent your explanation to them to see what they say?
Hi Peter,
But of course - I could be wrong and I’m always happy to learn 
Sarah
Sent it off see what they say….if anything?
Meanwhile it’s on “away” mode and looks like this but it’s showing the dips without any activity?
Hi Sarah
Looks to me that you’re correct. But not sure what we can usefully do with the info.
But I am interested in the mention of a snow setting to reduce snow pile up - not seen anything about it previously and a blast through all the manuals now finds no info on it all, never mind how to switch it on. Or could this be the ‘option’ mentioned on page 44 of the hp installation manual for ‘defrost’? And if not, what is it???
Also, there doesn’t seem to be any info on switching of the base heater during defrost.
A
As it was quite cold today (1-2degC), I tried to monitor my HTQ 8kW Outdoor Unit for a couple of hours with a MIM-C02N, hoping to watch how it performed a defrost cycle (I’d been puzzled by the Samsung control logic in post #4 above, and hoped to verify or otherwise…).
Well I didn’t see a defrost cycle (min evaporator R32 temp was -3.2degC versus the -6degC required to start one) but I did notice that starting from cold (after night-time setback) the compressor inverter frequency ran up to 57Hz within 10min of startup, with the HP delivering a shade over 10kW (based on measured m.Cp.dT) - that’s a full 125% of nameplate .
I also had a message from Samsung commenting that during defrosts the compressor speed is “about 60% of max capacity” (though whether that means 60% of 8kW or 60% of 10kW remains to be seen…).
Finally, if anyone wants to force an HTQ into a defrost cycle (e.g. to measure temperatures, flows, and heat requirements), this can be done by pressing the K2 button on the Outdoor Unit panel 3 times.
Sarah
Hi SarahH, can you tell me where to find inverter frequancy (Hz) on the Samsung controller menu?
