Advice on a Daikin Altherma 3 by Octopus

Exiled_Tyke

Thanks both these were both useful posts. I'd never discovered the information section of the MMI before even though I've looked all over the menus and manuals.  It is a bit clunky though being to the nearest kW but still really useful information. (unless you've found some more detailed numbers some where?).  So my system is currently looking ike a COP of 3 but it might be nearer 3.5 if I had the accuracy.  I haven't checked the WD curve as yet and can only presume Octopus set it up sensibly.   It's a shame more of this can't be done online or on the app (My MMI is in an awkward place!) 

Nick_Dr1

Yes, its really annoying that only some of the data is exposed by Daikin. As you say, even their own app is limited as it only has access to the same dat as everyone else. Lots of developers are moaning to them to expose more data but its falling on deaf ears at the moment. Its measured, but Daikin just don't let it out.
You can at least calculate the overall COP and weekly/daily ones if you can be bothered, by looking at the MMI.

I'm about to build a little add on module that will allow me to get to that data. Perhaps I will extend it to make a plug in COP meter!

matt_drummer

ESPAltherma

It already exists

The_Green_Hornet

ESPAltherma | Monitor your Daikin Altherma / ROTEX heat pump with ESP32

Wizard2

FreeBear said:

Wizard2 said: I'm in East Anglia and the radiators have 10mm copper pipes.

Would it be hard to go back to gas if we really hated it (the gas boiler is our last gas appliance)?

Is it just 10mm going to the radiators from larger pipes, or is the whole system plumbed in 10mm ?

If you find an ASHP unsuitable, as long as you still have a gas supply, it wouldn't be too difficult to reinstate a boiler. If you kept the ASHP as part of a hybrid system, you'd be able to run the HP at a high COP on the warmer days, and just use gas for a boost when cold outside. To convert to a hybrid system wouldn't be very cheap though. The money would be better spent on replumbing the existing system (bigger pipes, larger radiators) and improving insulation levels.

I've had a look at the current setup, and after doing some research, I think I mostly understand what all the pipes I can see do.

There's 22mm from the boiler to the hot water cylinder, and 22mm for the radiators, which goes into the floor. I'm not sure at which point it becomes 10mm piping. There's also a 15mm pipe connected before the pump in the airing cupboard, but I'm not sure what that's for.

The new water cylinder would be going in the garage, where the boiler currently is, since the airing cupboard would be too small for the new equipment. Octopus would use the boiler flow and return pipes with a new cylinder, and then hot and cold water pipes from the kitchen, which are 15mm. Does the size of the hot and cold pipes matter too much?

Thanks for the advice on the hybrid system. I think we'd get the gas supply removed - from what I've read, there always seems to be a way to fix a heat pump/system that's not working very well.

Wizard2

Adrian_Dorr said:

 Whey mean is that you can’t can’t change the design temperature. Using a weather curve setting the system will constantly change the temperature and only go to 50C when the outside temperature is at the design temperature, I.e. the minimum outside temperature that you get at your location (e.g. -2C in the south). 

You can change that in the settings later when you find that your house gets too warm. 

When you say it will only go to 50°C when the outside temperature is at the minimum, does that mean by default it'd typically be higher than 50°C, dropping to 50°C at the minimum?

FreeBear

Wizard2 said:

FreeBear said:

Wizard2 said: I'm in East Anglia and the radiators have 10mm copper pipes.

Would it be hard to go back to gas if we really hated it (the gas boiler is our last gas appliance)?

Is it just 10mm going to the radiators from larger pipes, or is the whole system plumbed in 10mm ?

If you find an ASHP unsuitable, as long as you still have a gas supply, it wouldn't be too difficult to reinstate a boiler. If you kept the ASHP as part of a hybrid system, you'd be able to run the HP at a high COP on the warmer days, and just use gas for a boost when cold outside. To convert to a hybrid system wouldn't be very cheap though. The money would be better spent on replumbing the existing system (bigger pipes, larger radiators) and improving insulation levels.

I've had a look at the current setup, and after doing some research, I think I mostly understand what all the pipes I can see do.

There's 22mm from the boiler to the hot water cylinder, and 22mm for the radiators, which goes into the floor. I'm not sure at which point it becomes 10mm piping. There's also a 15mm pipe connected before the pump in the airing cupboard, but I'm not sure what that's for.

The new water cylinder would be going in the garage, where the boiler currently is, since the airing cupboard would be too small for the new equipment. Octopus would use the boiler flow and return pipes with a new cylinder, and then hot and cold water pipes from the kitchen, which are 15mm. Does the size of the hot and cold pipes matter too much?

A table about a third of the way down on this page might be of interest - https://www.heatgeek.com/does-my-pipework-need-upgrading-for-a-heat-pump-with-cheat-sheet/ - A 10mm pipe will only be able to carry a little less than half that of a 15mm pipe. How much heat you need to pump through that pipe depends on the radiator size.

To my mind, 15mm should be fine for domestic hot water, especially if you have an unvented tank. Some say you need to increase the size to 22mm. I don't think it really matters as the taps will limit how much water will flow, especially if you have mixer taps with 8mm tails.

Nick_Dr1

If the hot and cold 15mm pipes are just feeding taps in the kitchen then it will be fine.

Nick_Dr1

Wizard2 said:

Adrian_Dorr said:

 Whey mean is that you can’t can’t change the design temperature. Using a weather curve setting the system will constantly change the temperature and only go to 50C when the outside temperature is at the design temperature, I.e. the minimum outside temperature that you get at your location (e.g. -2C in the south). 

You can change that in the settings later when you find that your house gets too warm. 

When you say it will only go to 50°C when the outside temperature is at the minimum, does that mean by default it'd typically be higher than 50°C, dropping to 50°C at the minimum?

No, it means that the maximum temperature it will heat the heating water to is 50deg. It does this when it is really cold outside to get the maximum heat into the house. Under these conditions the house is losing maximum heat through the walls etc.
When its not so cold outside, the house needs less continuous heat input as less is escaping. If you heated the water to 50 deg then the house would get too hot and the heat pump would turn off. Then it would turn on again later when the house has cooled etc . This is cycling. What the system does is set a lower temperature for the water if its warmer outside and so it heats the house slower, ideally just balancing the heat in against the heat out. Pump runs for longer (all day) but at a lower power input, sand this is efficient. Starting and stopping is inefficient.

Wizard2

Exiled_Tyke said:

@Nick_Dr1 how do you get hold of COP figures? 

In response to other questions.  Like Nick my ASHP hasn't been tested much so far.  My initial thoughts are: 

1. I'm very happy. I particularly like the more gentle constant heat of lower temperatures throughout the house. (not great for drying towels on the towel rails though) 

2. I also like having a cylinder rather than the combi boiler I had before. (especially hot water running through more quickly)  As I have an EV tariff heating water at night is substantially cheaper than gas heating. I also get the ASHP heating the house during the cheap rate in the early morning (the initial power up of the ASHP is quite energy heavy) 

3. It is taking some getting used to. As it is slow to heat up you can't just turn it on when you need it. But I'm sure that a higher base temperature is better for the house than how I ran the gas boiler.  

4. Octopus were a pain getting to installation. Pretty much everything that could have gone wrong did. A lot of it related to a restructuring of their teams and new staff taking over the project. Hopefully they are through this now.  From installation onwards they have been very good. The installers were very friendly and helpful. Post installation queries have been dealt with very promptly. 

5. I'm pleased they were able to keep my Hive TRVs in place. Turning radiators on and off frequently doesn't work with the approach needed to get the most out of this method of heating. However I have a few rooms which I only use at certain times in the week so having these programmed ahead is still useful.    

6. Overall with the removal of gas from the house; careful (shrewd/astute?) use of the night time tariff and also firing up on an afternoon while I still have some spare electricity from the solar panels means that I expect to make some savings over the old system. However I'm sure the worst days of winter will test this theory. 

It's good to hear that you're very happy! It seems that most people are happy with them, from what I've read.

Does anyone regret going with Octopus for an installation?