PhilT

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?

Go for it. Interested to know how you get on

The premise is wrong, every rad will have a different ΔT depending on the surface area of the rad, with an overall average ΔT of 5°C

All suppliers will most likely screw up at some point, even Octopus, who I am still with after two years, have messed up my billing countless times, but always fixed it immediately. What evidence is there to suggest Tomato will be any different?

With many people suffering such energy cost hardship, such an attractive price some may still consider this worth a shot though, what is there to lose if you do what everyone should be doing which is to control the payments, preferably monthly in arrears based on the bill.

Even if you don't have batteries or batch heat it's worth considering because it's always below standard variable rate and the fixed cost is also lower. What, if any, are the downsides?

Yes but with straight WC if you have a lot of south facing glass there may still be some "bounce" on sunny days, not really a big deal though

Mostly agree although gas power efficiency is abysmal (25% for non CCGT) and getting worse as gas turbines have to keep stopping and starting more and more with fluctuating renewables https://www.statista.com/statistics/548943/thermal-efficiency-gas-turbine-stations-uk/#:~:text=Thermal efficiency of combined cycle,in the UK 2010-2022&text=The thermal efficiency of combined,gas was converted to electricity.

Have you ever had a go at working out the capex/running cost of pure electric, using storage/E7, vs. the capex/running cost of a heat pump installation? Could be an interesting comparison and possibly a surprisingly close contest in terms of payback/IRR?

Can anyone actually see the accumulated hours by ToU on their smart meter or in home display. I can't see that for Cosy but possibly you can for E7?

Oh yeah sorry brain's gone walkabouts today, I'm putting it down to the servere distraction caused by COP29 and Milliband heat pump targets and boiler tax!

sorry I think I misunderstood what you said there, you mean your E7 at the same 13/8/3 ratio of std/cheap/expensive hours works out at 25p?

true but the question was "do you find the running costs are any cheaper than a std rate tariff"

13 hours mid rate tariff = standard rate, 8 hours at half price, 3 hours at 1.5 times, so it's a no brainer, even without a battery or any scheduling.

Mine does that in the earliest part of the heating season Sep/Oct - it shouldn't be doing that during the last 3 days - In/Out flow temp should be more or less constant, apart from the occasional defrost:

I take it you mean 55kWh PER DAY (= 385kWh/week)? That sounds about right compared to 180kWh/week during the first half of November, which was around 10degC warmer. My usage has also more than doubled over the last 3 days compared to the first half of Nov.