But that’s the point, I have a very low heat demand but will be getting a pump designed to produce 8kw where the bottom end isn’t the design criteria
Exactly the same issue as the 09 has in the high output range
Maybe.
But your heat pump consumes a minimum of around 280w I believe?
At a COP of 4 that gives you 1kW of heat, not a lot, certainly not excessive.
Try living with a heat pump that consumes a minimum of around 900w and puts out over 4kW of heat. And that comes with often a painfully slow and inefficient initial 60 to 90 minutes of a heating cycle. I don’t know anybody who is happy with a 9kW
There isn’t much room to improve at your low level of heat requirement, you can’t realistically use much less than 280w for a heating system.
But if you prefer to look at it this way, then yes, you have the same minimum performance of a heat pump with twice the maximum output of yours, just as we have with the 9kW.
I would say though that I would prefer to have the issue on your scale rather than ours…
Even on your 4kW model I would think you have a range of operation of 1.5kW to 4kW, maybe 30% to 100% of its rated output.
The 9kW has a range of operation of around 4kW to 9kW, something like 45% to 100%, it’s pretty limited and I find that I get more like 4.5kW to 5kW of heat at the minimum when it is warm outside.
If I only need 1.5kW of heat it is pretty tough to deal with over 3kW of excess heat, it mucks everything up, the Madoka doesn’t work and the heating cycles need to be short and often, something that I haven’t been able to automate.
It is -2c here at the moment and my house is at 23c downstairs and 21c upstairs. I am running at the minimum output using as little electricity as I can and it just about matches my heat loss, sitting in my conservatory of course!
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Is your back up heater in use?
Does it have a meter on it?
Your flow temperature seems to be increasing at the moment with little or no extra
electricity consumption.
You are also currently getting a COP of over 6 as the flow rate and flow temperature increases with no increase in electricity consumption.
None of it seems likely, maybe your BUH is in operation and you don’t know it?
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not considered that tbh will have a look tonight when i get back home
Even though I am using a fixed flow temperature with no Madoka influence at all I am now convinced that the Madoka does still exert some control over the heat pump.
My heat pump has been as stable as it could be all day.
I turned on an additional heating source in one part of the house as a test and very quickly the flow temperature started to decay where it had been stable all day.
I the turned up the requested flow temperature by 1c and and once it got there the heat pump shut down and did a short reset, not a full defrost, it was over very quickly just like the normal ones once every six hours. There was no ice in sight.
When it is warmer, even though in theory I have no room influence, I am sure it is the Madoka causing the decay in flow temperature I experience.
I can only conclude that the Madoka is always monitoring the heat pump performance and makes adjustments as it sees fit, as suggested to me by the Daikin engineer.
It makes it even more difficult to deal with and confirms to me that the heat pump, the Madoka and our house are not a good match.
Hi @KnightPhoenix Zak, please could you post your WDC and setup config over on this thread? HELP - Daikin Configuration WD curve and modulation with a Madoka room thermostat - #11 by matt-drummer
our pump has been running great, thinking of taking the risk of lowering the pump limit to see the result of the initial heat cycle, I would like the house to heat up a bit slower and not overshoot the room temp (shut down the HP) in milder conditions…
I’ve been reading with interest having just installed an EDLA11 for a client in the Alps. All working well so far, but the heat loss curve for the building crosses the 4.5kW (the minimum output as I gather from this thread) point at about +5 degrees. We’re a way from that right now, but I’m wondering what to prepare for when we get up to 5 and above regularly in spring. There is reasonable building thermal mass, underfloor heating with about 70l of water in it, but no additional buffer vessel. Some parts of the building are heated separately, so can “provide” additional heat loss if left “off” on the separate heating, and with the UFH and mass, I think I’m in a better position than just rads to prevent excessive cycling.
The system has no additional monitoring other than the daikin app, and the smart meter from the electricity company, so I don’t think I’ll be called to account in anything like the level of detail you have been analysing the EDLAs here thankfully.
More broadly, for the next ones, I’ve been struggling to find any manufacturers data on minimum output, is this kept a secret? Or have I been looking in the wrong place? What do daikin call it? I’ve got access to their document library. Thanks
Hi Phil,
It is not really a minimum output as such.
These heat pumps have a minimum electrical input of around 900w, it doesn’t matter how low you go with flow temperatures, that is it.
Therefore, at a COP of 5 at say 7c outside and 35c flow temperature you will get 4,500w of heat, that is it.
So I call about 4,000w the minimum output as I don’t really see why a COP of less than 4 is acceptable when other heat pumps do much better in similar circumstances.
Of course, you can turn the flow temperature down even lower and you get less heat, it just come at lower efficiency as the electricity consumption remains the same.
None of this is a particular problem if you don’t care very much about efficiency.
I find it annoying as my minimum operating parameters are the same as the 11kW unit you have installed and also the 14kW and 16kW.
So although you installed an 11kW unit you may just as well have installed a 16kW, your client has gained nothing by having the 11kW, maybe some money, but they have lost output capacity at the top with no gain at the bottom.
Your client may well never notice an issue, they’ll probably get a bit warm at 10c plus.
They probably wont get the best efficiency but even mine has never been terrible, just not what I hoped for.
Thanks Matt. I’m always keen to learn from others, and your posts have really helped.
I’m an independent Daikin installer (I’m free to choose another brand, but would need to reinvest in courses, manual reading etc), and it seems that in each range there’s essentially 2 models, “the big one” and “the small one”. Ie in the monoblocs that’s 4-8 or 9-16, with the 4,6 and 9,11,14 all being limited versions of the 8 or 16. I wonder if this is how the other manufacturers do it.
I can’t install a 16 where the heat loss says 11 as the French equivalent of MCS would fail me at audit, despite the hardware being identical. At our DOT of -18 the “big ones” all do about 8.5kW, so backup is needed.
Where this information comes into it’s own is if a client is in the 8-9-10kW requirement range. The “small one” can do about 6.5kW at our DOT, plus backup for those cold days being in the order of 9.5kW. The question then becomes what else can be done to get the building to lower the required energy only slightly to justify the “small one”.
I’ve not seen minimum electrical consumption quoted in the documents, is this commonly stated?
Hi Phil,
I wasn’t for one minute suggesting you had done anything wrong, I know why the 11kw is sold and why you fitted it, the same reason I got a 9kW.
I was horrified when somebody wanted to fit the 14kW here but I would have been in exactly the same position that I am now, just maybe short of a bit more money.
The sad reality is that they are all the same in their ranges as you point out.
The `smaller’ models i each range are a waste of time and just exist for marketing and to satisfy the MCS and their equivalents.
It’s probably also sad that somebody with an 11kw heat pump may have to resort to a BUH when they might not have to, or not so often with the 16kW unit.
I think this approach is unique to Daikin as far as I can tell.
I do think they are decent heat pumps though, well made and with a decent amount of customisation possible that I don’t think you get with all other manufacturers.
These heat pumps probably work better in a climate that is not the UK, somewhere a bit colder and drier.
The minimum electrical consumption just comes from our data and it has been confirmed by Daikin that it’s as low as they go.
They also have a massive circulation pump, the same in all models in the range, that in itself uses nearly as much electricity as the whole 8kW unit uses at it’s lowest input.
They don’t say any of this in the documentation and it would be reasonable to expect each heat pump to work over a similar range in relation to its nominal output.
I was surprised when I found out what they had done, like I said, it is not what you would expect and any reasonable person would think that a 9kW heat pump would work at a lower input and output than that of a 16kW heat pump from the same manufacturer.
To find out that they are identical was a bit of a shock and had I known that before installation it would never have gone ahead.
I have no doubt that the 16kW in a house four times the size of mine would be fantastic and I could make it work really well. It is such a shame that they didn’t scale it down in the correct way.
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Thanks Matt, I don’t think I’d have done anything differently with this client, so all good
The circulation pump is outrageous! It’s got heatsinks on it to keep cool?! Nice it’s got 10m head or something, but I’m ok with designing the hydraulics to less! I’ve never seen anything like it!
It’s certainly colder here, and my wife is looking for her 3rd humidifier, so she thinks it’s quite dry. Still get a good quantity of ice off the defrost cycle. I’ve got a couple of heated drains to fit on other models. The HT range have a connection for a drain hose and a power connection inside for a trace heated wire to go in/on the drain to stop it freezing. I was disappointed this wasn’t on the monoblocs…
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Hi Phil,
I am sure that if you have your heat loss somewhere close with your client then the heat pump will be good. I think it is well made and durable, it should perform pretty well.
It is important to remember my circumstances. My heat loss was calculated at 7.6kW when the reality is that it is only actually around 4kW at the design conditions.
If my house was more like they calculated then I wouldn’t be here having these discussions.
The other thing that was wrong were the radiator sizes, I always knew this and have only installed what I worked out I needed before I had a heat pump fitted.
I don’t think these heat pumps particularly like being much below 35c flow and I think to get the best out of them they need to be as close to this as possible at the lowest temperatures.
Mine is working really well below 5c outside, I have been able to run at 33c at -4c outside and it has been great.
But, because my heat loss is so low, the problems appear quickly as it gets over 5c outside.
My situation is extreme though, a big heat loss calculation error with the heat pump in the range with the lowest flexibility of heat output is always going to be an issue.
I am sure that many other installations will work well, it is really the 9kW that is the biggest concern for all the reasons given and the size of property that it is likely to be fitted in.
On the whole I am actually quite happy with my Daikin heat pump, it has a lot of nice features. If I didn’t know better and hadn’t seen other heat pumps data I would be quite satisfied. If my house had a slightly higher heat loss I wouldn’t even consider changing it, my decision to change it is marginal.
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Apologies if this repeats what’s been said by Matt and others above, but this is my current understanding of the EDLA09 in our mid-sized property (145m2) in Swindon. It’s easy to find on heatpumpmonitor.
I’m getting my head around the EDLA09 now and starting to make some progress. It only reinforces my view that it’s a poor fit for our house and I’m pursuing this with Octopus.
I’d been running it in weather comp with settings from 30 to 40C, so it was spending most of 2023 between 30 and 35 flow. This resulted in a COP of 3.0 for heating for our first year- not great.
I now know this won’t work well - the key thing I realised was that any given emitter (radiators in my case) has a maximum output for a given flow temperature, with most companies declaring a radiator output at dT50 (70C flow). At 50C flow, the common Octopus desing temperature, this output drops to 50%; and at 35C flow, only 21% output. I was mistakenly thinking that low flow temp always means high COP. Not here!
Using Daikin data, in January at 35C flow I see COPs from 2.5 (at -2C outside) to 4.0 (at 10C outside). I’ve not seen over 4.0 yet.
I now understand that the COP will be a function of the emitter output, and to get a high COP I need a high output power, this means a higher flow temperature than 35C, so this is what I’ll try in the next few days of mild weather. It will doubtless involve the heatpump cycling and also complaints of an overheated house!
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Hi Simon,
My system is having a pretty good day, relatively speaking:
Target flow is around 38C, with a delta T set to 4C on fan coils. I don’t think our system can reliably achieve dT of 5C, while 4C seems much more within its operating range. (I know Matt finds that radiators and dT 8C is best, but I don’t think that works for my system.)
I think, for my system, I get better performance if I can lift the flow rate above the minimum of 10.7l/min.
My current theory is that with a flow rate in the 11-14l/min range, the heat pump can make small temperature adjustments by adjusting the flow rate, while keeping the compressor/inverter speed / power constant.
If the flow rate is at minimum, it has to adjust the compressor, which I think is less desirable.
Experiment ongoing 
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I thought some thermal images would be interesting.
- A small amount of exposed connector leaking heat
- Nice and warm on the right hand side
- Pump is warm, but the really interesting thing is the tape heater at the bottom which is active
From my reading of the service manual this is the water inlet tape heater, E11H, which should NOT be active as the inlet water is >11C (I had the heat pump running…).
It’s like someone missed the AND in the coding / electronics. That’s another 33W I’d like to not use please.
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PS: I didn’t try and set the emissivity for copper pipe, so can’t really take readings before and after pump or BUH. I’ll probably wrap some black electrical tape around the pipes and try that another day.
If the inlet water heater E11H is on when it shouldn’t be, it could be influencing the R4T values as the temperature sensor is pretty close.
And if E12H “Water outlet after heat exchanger” tape heater is also on (hard to test without removing insulation), then that might explain the high readings for R1T…
R2T has no such tape heater nearby
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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. 
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.
https://emoncms.org/app/view?name=MyHeatpump&readkey=7034e0830547fb8e3d56978a24793bc0
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:
- We have 3 rads with microbore - however, my understanding is that the buffer should cater for this
- Our primary pipework to our UFH is 22mm - runs through our kitchen with 3 or 4 elbows. Inside the kitchen it’s uninsulated.
- 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