Hi Stephen,
Is there any setting regarding pump speed that limits the lowest speed that you have seen?
I have my pump at 60% when sampling.
I saw another parameter that was something like pump restriction, I can’t remember exactly waht it is called but I have never touched it.
I would be happier if I could get my flow rate below 10lpm, something like 7lpm I see in the smaller models.
The manufacturer’s spec sheet for Daikin Altherma 3 says you need 20 l/min (if this is the right model)
Hi @matt-drummer
No, the main pump limitation parameter is documented as limiting the top end (so not a good idea to use)
Pump limitation while sampling is fine and I’d go lower tbh that 60% if possible as that parameter is only in play between compressor turning off and then back on.
Hi @Timbones
Yes, that’s to allow for defrost etc.
If the system at max pump speed cannot handle 20l/m, my understanding is that it errors out and generates a fault.
I had assumed the pump limitation restricted the top end which is why I never touched it.
Thanks Stephen.
Thanks Tim,
Oh look, they all require the same, how strange! 
To add more detail and documentation on this point:
From the Daikin EDLA 9/11/14/16 Service Manual:
From the Daikin EDLA 9/11/14/16 Capacity tables/graph document:
e-b-d-la09-16d-3-v3-w1-eeden20-data-books-english.pdf (3.3 MB)
After reviewing the heat loss and radiator schedule from BG and Octopus.
I noticed that BG had missed a room from there heat loss calculations…
Then on the radiator schedule from Octopus the upstairs hallway shows as 2.
If I use the BG and add the utility in I get 7.7.
Take away the additional on octopus and I get 9.5.
My feeling is it’s between the 2.
I think with the LWT I can calculate it in the next couple of days if someone can show me the formula?
BG design for 40 @ -3 and Octopus 50 @ -3.
I’ve the 16kw HP, pretty sure there is no benefit of discussing reducing the size with Octopus from the conversations on here as I’d get the 9kw which can’t modulate further down than what I get now!
Main reason for reviewing is I’m thinking about upgrading our rads in our bedroom so we get slightly more heat from lower flow temps.
Hi,
With Octopus the radiator schedule is not representative of the heat loss. They include rooms twice on the radiator schedule if they have two radiators but that does not mean the full heat loss is included twice.
Any unheated rooms or areas are not shown on the radiator schedule although they will be included in the heat loss.
You’ve won!
As you say, there is no benefit in having any of the three `smaller’ models. They all operate at the same low levels.
Also as you say, the best way to take advantage of this is to ensure you have emitters than can exploit the full heat output at the lowest flow rates.
These heat pumps don’t really like and there is no actual gain in heat output by going below 35c on the flow temperature, 30c uses no less electricity than 37c
Just aim for 4,500w to 5,000 w of heat at 35c flow with around 900w of electricity input.
My experience is that this is the best you can do.
You need about 40kw of radiators (at dt50c as they are sold) to get that heat output at a dT between room and mean flow temperature of around 10c.
Now I have more than doubled my radiator output my 9kw works ok. It is much better today in defrosting territory than it was a month ago as I can now run at 35c flow even when it is 3c outside and we have 23c inside.
I still have more heat than I need but at least it is coming at the best efficiency it can for my heat pump in my house.
Not that it is problem because of the nature of this range of heat pumps but I have to ask, how did you end up with a 16kW model with a heat loss of less than 10kW?
I assume neither Octopus or BG installed it?
Octopus install. We had a calculated HL of 11kW.
We run DT 5 as we have UFH throughout downstairs.
Do you have one or two zones?
Single zone, used to have many more!
I think then it would be good to get your radiators capable of flowing 35c to get the desired room temperature.
