Performance of 9kW Daikin

It’s not a secret where there is nothing to hide.

Northern and central European vendors often publish tables. Those who don’t publish tables you probably want to steer clear of. :wink:

Maybe it’s the day and humidity but I’m really struggling to get anything decent out of my HP today.

I didn’t switch back to LWT last night as I wanted to experiment running with the Tado, unfortunately it completely failed to switch on until the inside temperature was 17 (setback of 17.5). So we’ve been playing catch up all morning.

We are getting 30 minutes then a defrost starts.

We are running the tight weather curve as most people do with a deltaT of 5.

There are a couple of things that I’ve always thought about the setup:

  1. We have 3 rads with microbore - however, my understanding is that the buffer should cater for this
  2. Our primary pipework to our UFH is 22mm - runs through our kitchen with 3 or 4 elbows. Inside the kitchen it’s uninsulated.
  3. I wonder whether the ABV should be open slightly - as we closed it.

We run a fully open system, at a bit of a loss this morning with the performance of it.

Heatpumps live and die based on system volume and flow rate.

If you have a buffer then the volume should be ok but if it is just a volumiser then you need to make sure you have maximum flow rates.

Personally ditch the tado and run on LWT or the madoka, loose all the TRV’s and use the lockshields and flow adjusters for the UFH to balance the system and let it run.

Also check your heat loss survey and make sure you have the right size pump.

Also from looking your system is cycling on and off, have you tried dropping the flow temp a few °c and letting it run longer. I got rid of my setback and dropped the flow temperature and that way it does not defrost as much and runs cooler and more efficiently

I’m trying to ditch Tado. Unfortunately, Octopus are dragging their heals replacing it.

No TRV’s and the system is fully open and balanced.

I’ve already found out that the HP is a little bit oversized. My HL was 10.5 - however, I believe it’s actually 9.5 or slightly lower. I don’t think I gain anything from swapping it tbh.

I’m wondering whether the weather conditions where just bad for it yesterday - snowing, near 100% humidity below 3 degrees and a driving NE wind. Unfortunately, that affects our living room massively - so we actually need a higher flow temperature to heat that room.

I’m wondering how much the microbore and/or the plastic pipes to the UFH would change things or just accept it was a bad weather day for it!

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For the living room, wouldn’t more emitter area/output be preferable to a higher flow temperature?

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We have UFH in that room - I’m not sure I want to rip up our floor again!

So I’m going to go down the route of improving the insulation…

The flow rate to that room has always been a bit problematic since we got the HP - I think we get a max of between 2 and just shy of 2.5 on the flow meter…

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For ditching the tado you should be able to go into the installer menu and select madoka or LWT and then configure a weather curve to match.

Regarding UFH the main UFH pipework will usually be plastic but ideally you want a nice big bore to the manifold and to have no additional pump or blending valve there.

If you have a high heatloss in a specific room you could always look into some of the designer radiators to add more heat to the room. Nothing to stop you mixing UFH with Fancoils or radiators provided they are all designed for the same flow temperature so you can run full open circuit.

Microbore and plastic will always be suboptimal (plastic more so as it is more likely to have lots of restrictive inserts) but may well be sufficient depending on how many emitters or how much power you are sending through it. Heat geek have a pipe sizing guide just for this and with plastic you need to go down a size due to the inserts (22mm plastic is more like 15mm on the chart).

Colder days will usually have worse COP but if you are oversized by any degree then you may find the COP improves at a certian point. Also daikin does have a setting to increase the flow temperature around 0 to compensate for defrost cycling and keep the house warmer. Could be worth looking at that.


2 posts were split to a new topic: Struggling to get good COP from Daikin 9kW

A post was merged into an existing topic: Struggling to get good COP from Daikin 9kW

I have the same problem (EDLA09 in a house with 9 kW heat loss at -8°C, located in Belgium) and learned allot on this forum, particularly on this topic.

I also have this 900-1100 Watt minimum consumption which gives me a bad COP (max 3).

I discovered also the heatpumpmonitoring site. There is one 9 kW Altherma which has an electrical consumption lower than 750 Watt…
I wonder how this is possible.
(Emoncms - app view)

Hi Geert,

The data for that heat pump is not reliable, there are times when it is using less than 500w of electricity and it even produces heat whilst using no electricity whatsoever.

This 9kW heat pump uses about 880w as a minimum and usually a little more.

Thanks Matt.
By the way, thank you for your detailed reporting of your experiences with the EDLA09. I have just experienced the same learning process this winter and it is very pleasant to see this confirmed. Many people have tried to convince me that lowering the supply temperature is the solution, but in the case of the EDLA09 this doesn’t solve anything!

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Hi Geert,

Yes, you are correct, the minimum electricity consumption is the limit with all heat pumps, and with this one it is quite high compared to the maximum output.

Apart from this it is a nice heat pump.

Be careful looking at data from non MID monitored systems, it is too easy to make adjustments to data in things like Home Assistant so you never know how accurate the data is and how it may have been manipulated.

As you can see, it can also make you think something is possible when it isn’t!

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It is a nice heat pump. When it is colder than 7°C and it is not too humid, I am quite satisfied.
To be sure, I asked my installer whether a swap to an EDLA08 is a possibility, but I think this will cost me more than the yearly benefits over 20 years…

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Hi Matt, there is already a discussion in the forum about that heat pump. It is not the monoblock units you guys have in the UK, but an older split system.

I also have a 16kw split system and have seen it draw just 700w, when 13deg outside and 28 deg LWT. Unfortunately I do not have a heat meter so can’t go into too much detail.

My unit is a ERLA16D2W17, currently pulling 920W at 9 degrees 34LWT. This includes 75W being used by the secondary circulation pump, so 850W ish. I measure this using a 3 phase meter with PF.

Probably the compressor is not the same as the monoblocks, very happy with it.

Hi Gonzalo,

Yes, I was only talking about the monobloc Altherma 3.

The system Geert was looking at is an Octopus installation which will be a monobloc Altherma 3, I don’t think they have installed the older split systems.

But I may be wrong.

Hi Matt, no you are correct, I was confused with the 11kw East Midlands unit.

How is your new 8kW treating you? What is your monitor link?


Hi Gonzalo,

The 8kW is much better in our house.

I am still experimenting a little with how to get the best out of it but it is pretty good already, I can’t see much room for improvement .

I am sure I could do better with COP if I ran the house cooler but I don’t really want to.

The efficiency is pretty good, the heat output is much less and we use a lot less electricity so I am happy.

My heat pump is the Octopus installation in Ipswich

Emoncms - app view

Random one does anyone know the latest firmware version for the EDLA09da3v3 please?

out of interest have you got a buffer or a volumizer, is it 2 or 4 port and does it have a secondary circulation pump. Have been thinking of trying a 2 port volumizer in the return pipe work see if this reduces cycling and helps defrost, happy to hear peoples opinions