PhilT

If you can get the data, John Cantor has a nice easy calc template, so you can at least sense check the output power. https://heatpumps.co.uk/heat-pump-resources/numbers-and-calculations/

15.5kWh average total input per day for that period is very good, for your house spec. Mine was around 20 for the same period but my COP was 4.2 but I only heat my DHW once a day to 40degC (using "Eco" setting) and never run a legionella cycle. 50degC and a Legionella cycle would probably explain much of your poor COP

This is the formula with a few example numbers. Set up a spreadsheet and model the variables to get your flow rate, or whatever parameter you want. Formula for Energy Delivery M x Cp x ΔT = Q flow rate coefficient temp diff output l/s water/glycol degC kW 0.35 x 4.085 x 4.00 = 5.7 litres/minute 21.00 litres/hour 1260 Water Cp 4.18 Fernox HP-5c @ 20% 4.085 -2.3%

Demand is the biggest obstacle - companies won't invest in the UK until things look a lot more promising. My nephew works for Vaillant (Belper). This year they had to furlough staff due to lack of demand. Vaillant Germany made staff cuts earlier this year due to poor demand.

Tomato looks unbeatable in certain situations but, worth repeating if you have PV, Battery, Octopus Cosy and Fixed outgoing, still at 15p/kWh, run the finance numbers with care as that export can make a big difference, for example on my setup (6,000kWk pa, of which 3,000kWh exported, 5kW solar and 3kWh battery) I am £250pa better off staying with Octopus, and would need a much bigger battery and/or UFH batch heating to warrant a move to Tomato. Not sure there is a better tariff for my situation at the moment but interested to hear what others with a similar setup think.

You need to look at this page and play around with the options because there are so many, not only different tariffs (x5) but different combinations of "heat source" (x4), "daily routine" (x4) and "Sustainability" (x3) https://www.tomato.energy/quote I must say it's tempting but there are two big issues - I get 15p/kWh for solar export with Octopus, worth c. £450pa - not available to me with Tomato. The second is the "honesty" factor - what are the implications for saying you only have a battery or battery/heatpump only (cheapest tariff) when you actually have solar which, if you are honest, would make it more expensive. Why are the Tomato tariffs organised this way and does that shead any light on whether or not it actually matters being honest?

looks like you may be right. Heat pump and battery only and you are quids in. If you are a pensioner it costs you more if you only have a heat pump. Solar even more.

what have the prices been across the whole of the year, on average?

Impressive. How much was your 30kW battery installation?

Me too. It seems to defy the laws of economics. I wonder how long it will last

Give Ecodan home owner tech support a call. They have always been very helpful for me

I can see this screen in the Melcloud app which suggests that you can set the mode by zone, but I only have one zone so I could be mistaken

In theory it can but with UFH in a kitchen zone, that's a huge (perhaps impossible) challenge of "learning" in a constantly fluctuating temperature environment, with all manner of appliances going on and off, warm bodies going in and out, sun coming through windows periodically, etc, and how isolated is the kitchen from the rest of the house - possibly different temperature air is wafting in and out? Have a go with the kitchen zone set to WC mode and see what happens.

Looks like it's only offered as part of the Tomatopia package, where they install solar panels and batteries for you, and charge or credit you accordingly based on their version of the "agile" tariff

When i spoke to a Mitsubishi tech about auto with ufh, he said it wasn't so much that it doesn't work, but rather it's an unknown quantity because they have no user data experience, and the software could take much longer to "learn" how your room temperature reacts to changes in heat input, you would need to leave it in a steady state 24/7, eg target room temp at 20degC all the time, until it settles. Do you have separate Ecodan remote controllers for each zone?