Octopus Heat Pumps

Spies

matt_drummer said:

You only have to look at the DHW performance to see that they are all the same.

The 4kW models heat water just the same as my 8kW. Have a look on heatpumpmonitor.org, they put out just as much heat when heating DHW, they are just limited in heating mode by software.

I and many others know that they are just software limited.

You gain nothing from the `smaller' ones other than cost.

My 9kW spent about 18 minutes an hour defrosting when conditions were prime for this.

My 8kW has only defrosted once and that was in the first couple of days until I changed settings, but I can run at 30c flow at 0c outside.

At 33c flow my 9kW was much better and defrosted less often.

At 42c with my original radiators it was 23 minutes heating and then 10 minutes defrosting.

It could never get to 50c, I tried.

Your radiator output is tiny, about 20% of mine.

You won't like me saying it but I predict a problem, sorry.

I don't think its too much of a concern other than hassle of getting them back to change the heatpump, I've heard of people getting them back and it only takes a couple of hours for them to swap it over. Maybe they're being overly conservative because ultimately its a cost to them for the higher capacity model.

matt_drummer

stripling said:

Spies said:

I've seen 6kw daikin units on heatpumpmonitor.org punching above their weight, my heatloss is 5.5kw (dt50/-2), the emitters total 6.4kw, I'm not too concerned and if it doesn't work, octopus will be coming back to make it work.

Glad its being installed in October as it shouldn't take too long to show whether or not its working correctly.

Yes, see the data sheet I have just posted from the EU installer's portal. It's very useful you can play with different configurations.  And yes, that's one reason that I stuck with them - the lead installer I met was great. As I said earlier in this thread they have a good reputation for putting things right.  

I'll be stalking you for feedback if you get yours in before me.  😁

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

matt_drummer

Spies said:

matt_drummer said:

You only have to look at the DHW performance to see that they are all the same.

The 4kW models heat water just the same as my 8kW. Have a look on heatpumpmonitor.org, they put out just as much heat when heating DHW, they are just limited in heating mode by software.

I and many others know that they are just software limited.

You gain nothing from the `smaller' ones other than cost.

My 9kW spent about 18 minutes an hour defrosting when conditions were prime for this.

My 8kW has only defrosted once and that was in the first couple of days until I changed settings, but I can run at 30c flow at 0c outside.

At 33c flow my 9kW was much better and defrosted less often.

At 42c with my original radiators it was 23 minutes heating and then 10 minutes defrosting.

It could never get to 50c, I tried.

Your radiator output is tiny, about 20% of mine.

You won't like me saying it but I predict a problem, sorry.

I don't think its too much of a concern other than hassle of getting them back to change the heatpump, I've heard of people getting them back and it only takes a couple of hours for them to swap it over. Maybe they're being overly conservative because ultimately its a cost to them for the higher capacity model.

I have had them back to change mine, it can be done in three hours or less..

Convincing them to do it takes some evidence and a bit longer!

stripling

@matt_drummer

Your radiator output is tiny, about 20% of mine.
You won't like me saying it but I predict a problem, sorry. 

No, it's fine you saying it. This has been why I have worked so hard to listen and learn.
As I said, I can't change the cost but I can try and haggle over the design and the rads - which cost them naff all as they buy so many. 

That's where I am with them now. Haggling over bigger rads.  
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. 

And as @Spies says, and your past experience demonstrated, if it doesn't do what it's supposed to do then they're more likely to come back and change things. I didn't trust BG on that score. 
All these are things that influenced my choice of install company. 

Spies

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?

matt_drummer

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?

What happens if it gets colder?

There is no detriment in having the 8kW over the 4 or 6.

They cost Daikin no more to make as they are the same.

How much Octopus pay for them, I don't know.

If the 8kW doesn't provide enough heat you can change radiators, if the 6kW isn't enough then you need to change radiators and heat pump.

There's no logic in making or fitting the 4 or 6kW

Pointless marketing to create a `range' of heat pumps.

stripling

@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 

matt_drummer

stripling said:

@matt_drummer

Your radiator output is tiny, about 20% of mine.
You won't like me saying it but I predict a problem, sorry. 

No, it's fine you saying it. This has been why I have worked so hard to listen and learn.
As I said, I can't change the cost but I can try and haggle over the design and the rads - which cost them naff all as they buy so many. 

That's where I am with them now. Haggling over bigger rads.  
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. 

And as @Spies says, and your past experience demonstrated, if it doesn't do what it's supposed to do then they're more likely to come back and change things. I didn't trust BG on that score. 
All these are things that influenced my choice of install company. 

Radiators are generally cheap for the popular sizes and adding more/changing is quite straightforward although that depends on how `clean' it needs to be.

I don't know why they insist on 50c, it's very silly and the extract from OEM shows it very well.

Getting Octopus to change my heat pump was not easy. I had another survey and they came up with another heat loss that was even higher than the first!

They are not interested in SCOP, as long as it meets the MCS minimum then that is good enough, to quote them, `we don't install efficient heating systems, we install cheap heating systems, if you wanted efficient then you should have gone somewhere else and paid more money'

They said they would change my heat pump but then disown me.

I couldn't do that.

I needed a sustained period at my design temperature and my OEM monitoring to prove to them that they were wrong. Then they finally gave in graciously and changed the heat pump on friendly terms.

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.

Demonstrating that your house was cold is probably easier.

Their usual mistakes are overdoing the heat loss and undersizing radiators.

I have not heard of anybody with an undersized heat pump yet.

stripling

@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. 

stripling

Here is the Daikin EU Installer's portal link

You can't can't set it up for radiators so I used UFH as the base plus my proposed heat pump and water tank combination. Have a play.