I’m surprised they are happy with 10mm. My system is mainly 15mm and gives no problem -despite the conventional wisdom that only 22 or 28mm will do - but mine is 2.25 as big a cross section as yours…If you have multiple rads off a single 10mm feed or have one high output (say above 1kw at 40/35/20) rad off a single pair of 10mm pipes then you might have flow limitation issues and you will hear the noises of the water flowing through the pipes. But if the installer is confident then I guess you can try it first.
The Daikin 11 kw pump is pretty powerful and I have the max flow on mine limited to 60% and it rarely gets to that level. Listen to the noise produced during nights when there is no call for heat but the outside temp is below 5c. Without Glycol the unit will switch on every 15mins (?) to circulate water to the outdoor unit so it doesn’t freeze up or actuate the frost valves. My 60% limit is to get below the audible noise level (waking me up) during such times. With 10mm you might find that even that flow is too noisy - but 60% is the lowest you can limit it to.
As you imply I wish they would calculate system volume first before insisting on a buffer tank but the only harm it can do is slow up system response times. Let them do it so they carry all the risks and not you.
Fight against a low loss header if proposed though - 2 years ago they were all the rage and I had to insist on my installer not putting one in. Common sense might have prevailed by now so your installer probably haven’t suggested one, They only have value if there are multiple zones all at different flow temps.
If you can remove your address from the top of the radiator schedule and upload it it will tell us what we need to know.
The main things to check are that no rooms have been double counted and that the coverage column is all between 100 - 110%, if you have some at 100% and some at 150%+ you are likely to have some hotter and some cooler rooms (not ideal if the hot rooms are bedrooms).
again if you would like us to take a look remove the personal info and upload it here and I will be happy to advise.
Hi @KnightPhoenix thats very kind thank you. I have uploaded the schedule. The lounge has two radiators, but it looks as though they have entered four on the schedule, although it would be the way their table works?
Currently your heat loss as estimated is 8,995W so around 1.7kW too much for the smaller unit. I would have a quick check on upgrades.heatgeek.com to see what heat loss they recommend based on postcode and EPC but if it shows over 7kW then realistically the 9kW or 11kW Daikin will be what you need (the 9,11,14&16 are all the same just software derated anyways).
Personally I would be looking to make the following changes either with Octopus or a plumber before they modify the system (obviously inform them if you make changes before going ahead with the installation).
bedroom 2 450 x 1000 (currently too oversized and may make the room too hot in the evenings when trying to sleep).
bedroom 3 bit oversized but not terrible, Ideally should be 450 x 800 (potentially not worth it for the cost)
En-Suite 2 with towel rail, Ideally upgrade to 1800 x 600 towel rail with btu of around 3000 @dt50. (1800 x 500 would only be slightly under design spec but way better than what’s there now).
Entrance hall / vestibule - warmer is ok as usually open to upstairs / house and can take chill off of coats.
Family bathroom - Same as en-suite 1800 x 600, and will emit less heat when covered with towels to dry (will give lovely warm towels in the heating season.
Landing - under 100 but made up for with excess from hallway downstairs.
This is, in my opinion what I would consider good for the 50°c flow temperature. If you wanted a lower flow temperature (which octopus do not like to do) then you would need to oversize all of the radiators to allow the house to heat evenly (the number in that last coverage column would need to read ~165-180% in every line to drop the design flow temperature to 40°c.
Currently for any line with a number below 100 in the coverage column the room may feel cold (except for the lounge where you add both together so it is 108%). For any room with a value over ~110% it is likely to be too warm, overheat and be difficult to balance with lock shield valves. The Octopus answer is to use TRV’s but when these close down you limit the systems volume and reduce efficiency.
While there are a few changes I would be asking for (and other peoples opinions on this will vary, I am a bit picky) overall it looks pretty good compared to some I have seen previously.
My 2c is to avoid reducing the size of any rads at least before the install and see how low a flow temperature you can run the system… if you are overheating in a room resizing the radiator later is relatively easy… Definitely agree with increasing rads otherwise
Incidentally I dont think we have any Daikin systems on heatpumpmonitor that run at anything near 50C flow temps (in reality). We only have one Daikin in a house built after 2000 and that was designed for 45C flow temperature and seems to run closer to 38C during coldest days. It gets a SCOP/SPF of 3.1 https://heatpumpmonitor.org/system/view?id=63.
thanks @TrystanLea and @KnightPhoenix. Very reassuring to get your views ahead of the install. No fixed date yet but hoping to go ahead in the next 4-6 weeks.
Not sure if you have committed to it but I have a Daikin 9kw and would never recommend it or the brand to anyone. Appalling SCOP, and very noisy compared to other brands. When it’s on you can hear an annoying humming even when some distance from it. Combine that with poor customer service I personally would steer clear.
I know others with Valiant and they are whisper quite with much better SCOP on similar built and sized property to mine.
July 2023. They are the same units. I would hate for you to feel as disappointed as I do. I would give anything to go back and go with the Valiant right now.
To give Daikin a little bit of a break here… My friend has an 11 kW Daikin on her 190 sq m 2018 house and I’ve stayed with her numerous times throughout the year. Never heard the heat pump. It just works. No monitoring beyond a smart meter, but total electricity consumption (no gas) was 6,000 kWh over the last 12 months, which seems reasonable.
I’d agree with Dan. I’m on my second house with Daikin heat pump and both were very quiet. 18 months into having a 14kW unit and it’s fine, and since I persuaded the installer to switch it to weather comp this spring instead of fixed 50C it works efficiently.
