Octopus Heat Pumps

matt_drummer

stripling said:

@matt_drummer

Is that system MID monitored or is it using EspAltherma? It makes a difference.
Interesting COP, pretty awful!
More worrying is that it's using over 2.5kW of electricity to do that and  indoor temperature is less than 20c
It's on it's limit and would be using around 70kWh a day at it's design temperature of -3c and that's at a flow temperature of `only' around 45c
Overall it is far from impressive!
There's nothing good about that and it highlights very clearly the problem of designing to run at 50c 

These are from Daikin's own EU installer portal. I think the EU has stricter rules about publishing technical data than the UK.  I have no idea how they monitor or collect data. 

I'll try find the link or the 35º screen shot.
I set it up to match my configuration then played with it at various leaving flow temps 

I trust my heat and electricity meters over any warehouse tests.

Daikin quote 62dB for the 9kW heat pump I had, and the 11, and the 14 and the 16! They also quote the same 62dB for my 8kW.

It's rubbish, my 9kW was very quiet and my 8kW is virtually silent! They can't all emit the same amount of noise when you actually look at the designs, the fan spins twice as fast on the 16kW as it does on the 9kW, the 16kW must be noisier. My 8kW is tiny compared to my 9/16kW yet they say it makes the same amount of noise, it's not true!

I don't care what anybody else says, heatpumpmonitor.org tells you all you need to know.

It's clear that flow temperature is what determines how efficient each particular heat pump is. My Daikin is the same as all the other 8kW Daikin heat pumps, it just does better because I can always run it at the most efficient flow temperature.

I also have a heat loss that is similar or less than those with 4 and 6kW Daikin Altherma 3 heat pumps, yet mine is still more efficient.

This is not because my heat pump itself is more efficient than any of the others, it is just what it is connected to.

Proof that the 8kW is no less efficient than the 4kW or 6kW even though in theory it is grossly oversized for my house.

That is because they are all the same.

matt_drummer

stripling said:

@matt_drummer<br> <br>I'm not sure how you would demonstrate to them that they had got it wrong without a heat meter, certainly on the basis of inefficiency.

I know. Plus even for myself to really get on top of efficiency. I'm wondering if I at least buy an electricity meter - like an EmonPi2 or similar - the 🐙 spark may fit it. I've heard they have done this for others occasionally. Maybe I can add the rest of the kit later when I can afford it. 

I am big fan of the OEM system as I think you know.

To be clear, I have no affiliation with them, I just don't know how I would have got to where I am without it.

There's always EspAltherma, but you need Home Assistant. I have all the stuff to do it as I couldn't get Octopus to fit the OEM kit. I did the plumbing myself in the end and got an electrician to do the electricity meters. 

It would be really easy if they fitted it at installation, I don't understand why they don't offer it.

They fitted OEM to 50 installs for free just before they did my install.

I don't like EspAltherma, it's a neat idea but it is open to and is abused plus I find Home Assistant a nightmare, just trying to install it on a dedicated computer is a challenge!

matt_drummer

stripling said:

@matt_drummer<br> <br>I'm not sure how you would demonstrate to them that they had got it wrong without a heat meter, certainly on the basis of inefficiency.

I know. Plus even for myself to really get on top of efficiency. I'm wondering if I at least buy an electricity meter - like an EmonPi2 or similar - the 🐙 spark may fit it. I've heard they have done this for others occasionally. Maybe I can add the rest of the kit later when I can afford it. 

Initially I just put a CT clamp meter on the heat pump supply cable just to check electricity consumption. Cheap, easy to fit and can be seen via an app on my phone. Plenty accurate enough.

The problem is monitoring the heat produced.

You need to know flow rate and dT between flow and return.

The OEM system gives you this and then you can see instant results for any changes you make.

It's really difficult to change something and then wait days to see if it has made it better or worse, if that is even really possible.

There are so many setting with the Daikin controller that make trial and error style adjustments virtually impossible.

It's a shame that Daikin and other manufacturers don't offer better monitoring. All the data required is within the heat pump, not 100% accurate like dedicated heat and electricity meters, but it would make optimising the system possible without adding extra stuff.

Its' a bit of a shame.

Spies

I think I definitely need an ESPAltherma on it from day 1 to get any meaningful data, looks fairly simple to fit, just 4 dupont wires on the heatpumps serial port

stripling

Spies said:

I think I definitely need an ESPAltherma on it from day 1 to get any meaningful data, looks fairly simple to fit, just 4 dupont wires on the heatpumps serial port

"fairly simple...." that's what Github guys say and I'm left with a fried brain 🤯😂

If you can describe the process like you are teaching a 4 year old - I'm all ears. 

john-306

I've just had a date of mid September for my octopus install. 
8kw Daikin. 5.5 heat loss, 50 Deg @ -3.4, 6.5 rads.
Upgrading 5 rads including 2 bathroom ones.
I'm hoping I won't be paying any more than the old gas boiler to heat the house once removed.

Very interesting reading....
 I may have to increase radiator sizes again to get lower flow temperatures and high cop, or put up with higher flow temperatures and low cop to heat house comfortably.

 

FreeBear

Spies said:

If the emitters can only output... say 6.3kw@dt50, what's the benefit of having a 8kw heatpump attached to them? are you suggesting a 6kw unit will never reach dt50 at -2?

6.3kW@ΔT50 is only ~4kW@ΔT35, and just 1.5kW@ΔT15. If you are running the heat pump at a flow temperature of 35°C, an 8kW output is going to be plenty.

stripling said: I then did my own heat loss assessment on Heat Punk. (That was a bit tedious to set-up, I admit).

Is that Heat Punk a web based application, or running under Windows on a desktop ? If web based, I may well give it a go, but no point in going through the registration process if it is Windows only software.

stripling

@FreeBear

It's online - here you go: here's the link 

Spies

Argh this is now weighing on my mind to the point I've emailed Octopus to double check 6kw is enough as @john-306 has less heatloss than me and they've spec'd an 8 over the 6 they have for me. 

Reed_Richards

stripling said:

Meanwhile, my radiator schedule just has a blank for the bathroom - so I'm leaving the (85w @ dt50º 🤦🏻‍♀️)  towel rail in and trying to get the most powerful smallish (designer) radiator added to another wall and my local plumber will fit it. Every watt counts! But it's more expense. 

Get Octopus (?) to fit a bathroom radiator that can be swapped-out for the designer radiator you really want.

My radiator schedule accounted for every room and corridor in the house.  I had to sign-off against:

1. An unheated corridor, on the basis that radiators in adjoining rooms were a bit oversized.  That has been fine.
2. An underheated bathroom, on the basis that heat would spread from the adjoining room.  That room already had a radiator/towel rail and I couldn't see a way to fit anything more.  That room can be a bit on the cool side in very cold weather and I've now figured out what I should have done, so that was a bit of a mistake.
3. An underheated kitchen.  I should have sacrificed a shelf to fit a taller radiator but we decided against.  In cold weather this room is really chilly first thing in the morning but reaches temperature eventually.  I have now figured out where I could have squeezed in an extra radiator so another mistake.

This was in 2020 so way before Octopus started installing heat pumps.  But my installer was accommodating and we went through 3 iterations of radiator size and placement.