Settings for NIBE F2040 & SMO 20 - Air Source Heat Pumps (ASHPs)

RE: Settings for NIBE F2040 & SMO 20

Mike @ Camelot — Mon, 04 May 2026 10:32:10 +0000

Thanks. Will do.

RE: Settings for NIBE F2040 & SMO 20

sc2987 — Sat, 02 May 2026 14:26:45 +0000

@lizzie sorry, I didn't get a notification for your response. I've only just seen it because of the other post.

I already changed that setting and it was still doing it. I have come to the conclusion that it will always do it, to release excess heat from the hot water into the radiators.

It seems very inefficient though; why not just leave the heat in the tank?! Especially since we have it set on the lowest hot water setting, so it's not like it's at risk of exploding from the pressure. I don't mind if it's a few degrees hotter than I set it to be; again, it's not at risk of burning anyone in that case, as we could have it set much higher in the first place.

@mike-camelot you might be better off starting your own thread, as more people will see it, and it's on a different topic (even though it's the same heat pump). And more people might have experience of it by now, compared to when I asked.

RE: Settings for NIBE F2040 & SMO 20

Mike @ Camelot — Sat, 02 May 2026 14:16:35 +0000

I have an F2040-12 and an SMO 20. It is supplying a Wunda Fast response UFH. I run "open Loop" with all of the zones except the bedroom open. I have an open plan single story house which is very airtight, an MVHR, and very insulated. The temperature throughout the house only varies from 21C to 23C. I have installed thermostats on the recirculation pumps for the UFH so they only run when the heat pump supply exceeds 27C and switch off when the heat pump switches off and the temperature falls below 26.5C. This setup seems to be working reasonably well, but I am thinking of adding a BT 50 internal temperature sensor in the lounge area. Because of the construction of the house, the temperature varies very little unless there is a significant change in the outside temperature. However the heat pump is still cycling between 1.5 to 2 hours (except when the OAT is above 15C approx) with a run time of approx 40 minutes. Is there anyone on the forum has the BT50 fitted, and if so what is your experience?

RE: Settings for NIBE F2040 & SMO 20

Lizzie — Mon, 24 Jun 2024 13:10:41 +0000

@sc2987

Hi, sorry to take so long to reply and I hope you have found the answer you were looking for. I have joined specifically to answer your question.

Do you have the User's Manual (as opposed to the Installer Manual)? You will find the answer on page 40 - Menu 4.2 - Operating Mode. The default is Auto but you can change it to Manual and then deselect 'heating'. In this mode you can't block the compressor but as you only need it for hot water it will only come on when you are running the water heating.

I agree with you that the menus are labyrinthine and not exactly user friendly.

It seems there aren't many people on this forum familiar with Nibe so I hope you find this reply. Again sorry for taking so long.

Settings for NIBE F2040 & SMO 20

sc2987 — Mon, 20 May 2024 11:14:28 +0000

I have a NIBE F2040 with an SMO 20 controller. It was installed last summer, and I changed some settings to our preference, which worked fine. And I changed them again for winter; also fine.

We also have solar panels (no battery though; we can only use the electricity as it's produced, during the day).

But now I have been trying to change the settings back again for summer, and it won't do what I want. I have read the manual, but it is just the menu system in paper form, with no extra explanation, or examples.

I know how to navigate the menu system; I just don't know which settings to change to get it to do what I want! It is so labyrinthine, and there seem to be so many different places you can change settings that affect the same things.

I can't remember exactly what I did to it last summer, but I have tried all kinds of things (and factory reset it before changing things again), and it still won't behave.

I want the hot water on from 08:30-20:30. The heating not on at all (either heat pump or additional heat). So I block the compressor overnight.

So there should be no activity at all between 20:30-08:30. And from 08:30-20:30 only the hot water (including the periodic increase, which we have set to the middle of the day, not the night as it is by default).

In the morning, I can hear it turning on to heat the water. But it is also heating the radiators, which I don't want it to. It can't be a disposing of excess heat thing (does it do that anyway?), as the hot water will have cooled down overnight to some extent.

I am not sure if the heating comes on at any other time or not (that may just be because it's warm at the moment though); I feel like it might have been on in the evening recently (which obviously I also do not want), as I've heard pipes creaking like they do when they expand and contract, but I haven't noticed the radiators getting warm at that time, like they do in the morning.

Don't ask me what my current settings are (they're a mess); I will just factory reset it again, when I know exactly what to change this time.