Been 12 months of going Green. Solar, Batteries and EV charger are very easy to understand hence now installed but ASHP has made me pull my hair. I cancelled one install by Octopus during summer as was unsure due to wide range of ASHP suggested by various big name installers. From 8kw to 16kw.
Now going back and have advised Octopus to install one. They have advised me 8kw Daikin. My heat loss is 6.8kw. I pushed them hard to go a level up, 9kw Daikin, which they have now agreed as I told them to do a re-cal heat loss at 21c for all rooms which led to 7.1kw heat loss.
Background on property: 2009 built and 210sqm.
Design: 50 @ -2.
The main thing to appreciate is that there’s a whole world of difference between the 8 and the 9kW Daikins. It’s not just a 1kW extra.
Daikin make 2 HP chassis, a small one (4,6,8 kW) and a big one 9,11,16kW)
Your choice here is whether you get a big chassis or a small one.
I spent about 9 months persuading Octopus that they should install an 8kW at my house when they wanted to install an 11kW. The major difference is in how much the HP can turn down to a minimum output on days when maximum output is not needed (ie most of the time).
The problem with having a higher minimum output is that a) you need to supply a higher minimum electrical input and b) you need to find something to do with all the heat that you don’t need.
Do a search on the forums and you’ll find plenty of threads from folk who have had their large Daikins replaced with smaller ones and are much more satisfied.
Bottom line is: get the smallest HP that will cover your real-world heat loss - which may well be lower than your MCS calculated heat loss.
Thanks for your explanation and it seems the tech member of Octopus tried to explain me the same…8kw has low modulation which is suited for my property making it very efficient.
I guess outside opinion like ours match theirs so I may ask Octopus to reverse contract and go for 8kw.
Do your research on this forum, as pointed out go for the unit that can modulate down, the 9kW will not, trust the experts and others on this forum, if your heat loss is 7kW then go for the 8kW, IMHO you do not need the buffer/and peace of mind as you call it unless you like high electric bills.
Thanks for the advise and have decided to go with 8kw Daikin. Data on heatpumpmonitoring seem promising for this model compared to 9kw. My plan is to leave the HP running 24/7 @ 50c/-2c, 20c and DHW @ 50c with auto topup @ 40c.
I would be happy with scop of 3.5 and believe to achieve 90% of electricity usage at EV off-peak rate due to usable 15kw battery size.
My current gas bill is £1k (excl. cooking) and expecting it to drop by 50%, even more. If this happens, I really can’t ask more from the system. Long run risk is these off-peak rates disappear in the near future…
Good plan! let’s save the planet together, the HP was the last piece of the burning carbon jigsaw in the household issue, we also ticked the EV’s, solar, battery’s, Rainwater harvesting boxes.
On our second winter and our 8kW Daikin is awesome, COP around 3.5 last night at zero (plus 6h night @ 7p a kWh makes it really cheap to run), >5 on a typical autumn/winter day – note we do not have a conservatory and a reasonably well insulated 200-year-old house.
Hoping I can replicate your numbers…they are coming to install next week. Looks like they have less install request in winter hence quick turn around. 5 weeks from online quote to complete install (end of next week).
Once installed, will ask for your help with advanced settings (if any) for HP.
I consider this kit to be essential if you want to do any close monitoring and optimising of your installed heat pump. The information and displays provided in the Daikin display unit simply don’t give the necessary detail to inform subtle changes to settings.
The easiest time to install the heat meter is during installation of the heat pump when the installers are cutting all the pipe runs. After this time, the system will need to be at least partially drained to allow fiting of the heat meter by a third party which may be contractually awkward with the original installer.
They did for me - but before they arrived for the install I had already connected the electricity meter in the consumer unit and had mounted the heat meter display adjacent to the agreed pipework run.
I had also connected the three data signalling cables to the Data logger box. At this point I knew all was working correctly, just with static zeros in the data. So all that was required was for Octopus to do the plumbing of the 2 parts of the heat meter - One part in the flow and the other in the return.
One gotcha is that there is an optional sensor that is triggered by the hot water motorised valve ( so that the logger can differentiate power and heat used for DHW and CH cycles). This sensor comes in two types depending on the make of motorised valve fitted. Octopus fitted an ESBE valve on my system. Check if it will be the same with yours and if so, make a note to the shop on your logger order to this effect.
If you ask Octopus to install the entire thing from scratch they may be less keen to get involved.