Daikin Monobloc Heat Pump - User guide

Hardware Heatpump
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Hi All,

Since my HP install in May 2024 I have been trying to understand the settings in the MMI and what I need to worry about changing and what effect each item has on the overall system.

So, I started to create a short form user manual for myself so I don’t have to look at the main Daikin manual very often (hopefully never as it’s a horrible document).

I was thinking does anyone else feel like collaborating to make a useful document that will help other out?

I have made a start and would like anyone else to point out where my document can be improved, add additional information and generally make a really useful document that incorporates our collective wisdom.

If you want to add or comment please PM me and we discuss how you want to get involved.

Here is a link where I have got to so far.

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Hi Dean,

Thanks for doing this. The doc looks great & is easy to read and understand.

Nice one. David.

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I’d actually been thinking of doing something very similar, though perhaps more along the lines of a glossary of terms (modulation, etc.)

I think that modulation allows the heat pump to vary the leaving water temperate depending on how far away the room temperature is from the target. So eg after an overnight set-back, the room temperature might be a couple of degrees low. If the WD is set perfectly, the flow temperature exactly matches the heat loss, but this merely maintains the temperature, whereas you actually want to increase it.

But I could be wrong.

Not sure how modulation and overshoot interact - perhaps if you have modulation, overshoot isn’t needed ?

One suggestion: on the MMI, if you press the help button, it turns on a breadcrumb mode - it shows numbers in the top left which shows which menu / submenu you’re in. It might be helpful to include those numbers on your document to make it easy for people to navigate to a particular config page.

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Indeed modulation varies LWT, though with a rather simple algorithm, at least for my older hybrid, but I think it might apply to the monobloc too:

-if the room is too warm for more than 20 minutes, the LWT setpoint is lowered by 1 step size (which is 25% of the max modulation setting [9-06] which is default 5C (max 10C), so default step size is 1.25C),
-after another 20 minutes of the room being too warm, LWT setpoint is lowered by 2 step sizes,
-until the room temperature goes below RT setpoint, in which the LWT setpoint goes back to regular, or if the room temperature is more than 0.5C too warm, the heat pump switches off,
-and if the room is more than 0.5C too cold, the heat pump switches on (if needed), and after 10 minutes being more than 0.5C too cold, increases LWT setpoint by 1 step size, and after 30 additional minutes, increases it by 2 step sizes,
-if room temperature rises above 0.5C too cold, LWT setpoint increase is limited to 1 step size, and if room temperature reaches RT setpoint, LWT setpoint is set back to regular.

There is no interaction between modulation and overshoot other than that the not so subtle LWT change due to modulation can trigger an overshoot so it is best set to 4C.

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Thank you Arnold this is the best description for Modulation I have seen. Modulation has always been a bit of a black hole that had no definition. I have included this in my user manual if thats ok with you.

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Thanks Dave will look at the bread crumbs idea when I have some time.

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Hi Dean, absolutely fine, though may be worth checking if it works the same way on your model.

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I have had an 11kw Daikin Monobloc for a couple of years and only recently realised that there seemed to be a control and scheduling problem which, after a lot of work, I have finally solved so wanted to share the solution as it looks like a software bug with the Daikin. I trust this is a good thread to share this.

I have a single zone with Room Temp (RT) control using a Madoka. I use a WD curve with a small 2c modulation.

A few months ago as I realised that the Leaving water temp (LWT) did not seem to be following the obvious control logic I started looking at the set points which I can see as I am monitoring the P1P2 data flow.

After switching off overnight due to a set back temp of 17c the unit would come on at 7am when the schedule asked for 19c. with the LWT at the WD set point … so far so good. After a few hours when the RT set point seemed to have been reached the LWT would drop by 4c below the WD point. I had never set 4c modulation and even when I switched all modulation off it continued to do this. When the RT schedule later increased the setpoint by 2c the LWT did not change and so no progress was made to the new, higher RT setpoint. It seemed to be modulating down and not up. Two Daikin experts who came to service the unit had no clue what was causing this.

Eventually I traced the problem to a ‘Ghost’ LWT schedule that I had set up when trying out LWT control. When you set RT control the schedule appears under the ‘Room’ menu and there is no schedule under the ‘Main’ menu so you assume wrongly that only the RT schedule is in control. It seems however that the hidden LWT schedule still has some influence and that the actual LWT operation is some mixture of the two schedules.

To Fix this you have to temporarily set control as LWT control and then delete the ghost schedule under the Main menu. Also turn WD control off and then back on before you switch control back to RT control. There is nothing in the manuals on this and I suspect that Daikin are unaware of this Bug.

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Hi!

You are correct, I discovered this ‘ghost’ LWT schedule myself shortly after getting my unit installed. We have an oversized 16kW unit and the most it has ever produced in a day is about 200Kwh, so about 8.5kW average. I guess our heatloss would probably be about 10-11kW at -2ºC.

To be honest, for me it is a godsend. We like a 2-3 ºC setback at night, and due to our oversized unit, LWT control was impossible to get good results from.

Therefore, what I have is a 20ºC RT at night (11pm-8am) and 22ºC elsewhere. I also left the ghost LWT schedule, with a setback of -4ºC between 9pm and 9am, and -2ºC from 9am to 11am.

The end result of this is that, during mild weather, RT schedule rules, an the HP is only ON for a few hours during the day (say 8am to 2pm, for example). During cold weather, it is ON most of the day, maybe off for 2 or 3 hours after 11pm, depending.

I also have quiet mode at night, to help with defrosts.

This, when considering that I live in central Spain, where night temperatures in winter fall below 0ºC most nights and climb up to 10-15ºC during the day, my HP works less hard at night, and harder during the day, when air temperature is higher.

We are very confortable, and obtain great results (if Daikin reported energy generated figures are to be trusted). The COP for heating this December so far is 4.9.

Usual LWT curve is 30ºC at 10ºC and 40ºC at -5ºC, but due to above rules I have not seen it above 36ºC yet. No modulation.

Hope this helps someone!

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I’d forgotten about quiet mode - it’s a pity that most of the configuration requires installer mode. I’ve just set that up now, to see if that improves the behaviour after defrosting. (Seems to go into a high consumption state which just frosts it all up again fairly promptly.)

Speaking of freezing conditions… does the pump operate even when the compressor is off (eg above target room temperature) when it’s cold outside, to prevent the outside water from freezing ?

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Yes. The circulation pump will run periodically to keep the outside water well above freezing. This pulls some heat from your volumiser (if you have one), or maybe from your DHW tank.
eg. Emoncms - app view

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