Odd behaviour when hitting strong man on Daikin Hot Water Boost

I noticed something odd.

Hit the strong man on Daikin app to get hot water tank up to 48 degrees while agile prices were on the cheap. App was just stuck saying Heating 48 degrees though

Draw from electric was then showing as 5kW plus going to the household then open energy monitor was only showing 2.7kW draw and COP 0, dropping further below zero too

SCOP was down to 2.3

Is this a fault?

Also how often do people top up their hot water tanks, seems I’m topping up daily as it drops from Comfort Mode 48 degrees (early hours agile at a few pence per kWh) to 39 degrees by the morning 8am and no hot water taken. Is that normal? Have Daikin 240L tank. Does the energy used by the immersion heater not get monitored, if so is that a fault that needs rectifying? Seems to affect the SCOP.

Is that heating the Hot water tank and is it heating the house, it says heating to 21.0 degrees but its saying 22.0 degrees too.


More oddities on my install. Seem to be pulling fair amount of power but showing up to temperature is this power for heating the home or the hot water?

No expert here… but:
Onecta app screenshot shows

  • Climate control: grey temp is current room temp - you have a Madoka? “Heating to…” is target temp on Madoka; so pump won’t have been heating the house at that point
  • Hot water tank: grey figure is current temp (46); “Heating” just means it it could be heating it if it needs to

Looking at a specific window in your MyHeatpump display, I am a bit confused about what’s happening:

You can see the HP is heating 2:31 - 2:39, then it looks like the immersion takes over, using 3000+W to raise the tank temp. But the flow temp is still going up! I also checked the flow rate (Show Detail, check Flow Rate box) - there is no flow during the 2:39 - 2:54 section. Weird. The flow turns on at 2:54, but there is no heat generation, because the Flow/Return temps stay the same.

When my HP does disinfection, the HP flow gets to 50+C, then the immersion cuts in to get to 60C, but the flow temp drops because the HP isn’t working any more. Curiously, your flow temp keeps going up, with no obvious input! The Flow Rate seems extremely low - around 0.4-2 units. I would expect maybe 10-30 lpm as a range.

Are you sure you’ve got the right data connected? Where is the electric power number taken from, relative to the HP, immersion etc?

However, I haven’t looked at a Hot Water "Powerful’ session, maybe that’s what it does…

It might be worth exploring the data using Graphs - you can check other items like Tank Temp if you are tracking that.

Nah, this is more likely to be trapped air in the system messing with the flow sensor. It’ll take a few days to clear itself.

The booster heater/immersion heater is on a second circuit to the heat pump? If the CT is monitoring the HP circuit it won’t see the immersion power.

I have just fixed a similar issue myself.

If you have recently drained the system or swapped out any radiators then please check that you have the right amount of inhibitor in the system and that you run an air purge and open the AAV’s to allow the system to vent.

As others have said it is likely to be trapped air round the heat meter.

Thank you, I have Octopus coming out tomorrow for post install will point them in the direction of these. One thing they mentioned.

You could have a mixer tap/ shower that is potentially passing cold water back up the hot. Again, potentially, I’m not saying you have! If this has been happening for a while, then there would have been no way of monitoring it before the cylinder was changed as the temp was hotter. Non return valves on all the outlets would stop anything from getting back into the tank. You don’t have a dhw pump ( secondary return )

Justin, you should get them to alter the parameters that decide when to switch on the immersion for normal hw heat up. It always comes on with powerful hw but should rarely or never be needed for normal hw heating.
The field codes i have work well,

4.03 =0 restricts the immersion /booster
8.01=75 mins , max hp compressor running time
8.02=1 hour anti recycling time
8.03=60 mins booster heater delay timer
8.04=95 additional running time

The installation manual is incorrect and badly explains the way some of these work and interact…i have found out by trial and error.

The fast cooling of your hw tank is a puzzle though…unless the pump is still running when the compressor is off and the 3 way valve is on the hw loop at the time. Ask them to check.

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Just looked at one of your hw cycles

The compressor and so flow starts but only runs for a short time before the immersion cuts in (my codes above should fix this ) but then a very small flow restarts and the Flow temp does not decline alongside the return temp…so with no heat input it looks as if heat is being taken out of the tank. I cannot understand why this does not show in the return temp though so suspect there is some sort of issue there. Please also see posts on this other topic about setting you hw schedule to much improve your efficiency. I’'ll try and link it in the next post.

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I just showed the octopus engineer these settings and he said he did not have a clue on how to set them.

Checked the filters on heat pump and small tank in garage. All clear as only just installed it.

The job is going to be audited apparently.

Checked the inhibitor levels, bled all the radiators. Could hear air in the ones upstairs the filled tank up as dropped to 0.5 bar

Also said need to remove filling loop connection when done.

Out of interest here which heat meter are you using.

Would you be able to check the flow rate on the MMI when it is showing as no flow?

Do you have a set of temperature clamps you can pop on the primaries to check if it is the heat meter not reading flow / heat or if the system is being funky?

Only thing I have is what they fitted.

These are the photos of the whole installation.

Why when the heating is set to 20 degrees during the day would it say it is heating up to 26 degrees?

Looks like you have the Kamstrup heat meter (same as me), feel free to have a look through the forums but @TrystanLea has mentioned previously that these can have issues with dissolved air in the system.

It may be beneficial to try another air purge from the installer menu or using the ESBE valve try and switch from space to DHW and see if any air comes out on a manual purge (doing this quickky. An bounce the coil inside the cylinder and dislodge any trapped air.

Alternatively you can get units that will remove dissolved air but ideally the less stuff you have in a system the better.

Octopus will have to do this for me, I have not got a clue where to begin with that.

Why would they fit parts they know are faulty? It has gone to a audit now I was told by the guy who visited for the post install courtesy visit

Another bit if information. when you flush toilet, there is hissing sound from the hot water tank, like it’s filling up again just from the flush.

This is not a faulty part per-se but possibly that these meters are more susceptible to dissolved air in the system.

This happened to me after octopus changed half of the radiators and forgot to put inhibitor back into the system (grabbed a bottle of x100 from toolstation and filled it via the magnetic filter).

Trystan covers this in more detail here - Kamstrup Multical 403 Erratic flow readings - #28 by TrystanLea
May be worth a read as it will help you explain what may be going on.

What I did do is turn this down on my phone and it went from taking 500w of electric to 10w
Thought the schedule is at 20 degree phone was showing heating to 26 degrees