PhilT

It's that power spiking which is interesting. The Ecodan never does that in auto mode, just a smooth ramp up, however it does spike considerably in WC mode. Great COP though

that's the whole point you shouldn't have to try at all!. It should be built in as standard and operate in the most efficient way automatically, never cycling and never operating at less than the most efficient power level

It's quite surprising that not all modern brands/models have this capability built in as standard.

m2 for what, just the floor area or every part of the internal surface area, floors, walls and roof ceiling?

It's a shame ASHP manufacturers don't provide some kind of programmable "power level" control in addition to WC and fixed flow temp. Or even an option to simply prevent the ASHP from going below minimum power, with operation limited by room temp. That would at least be a step in the right direction.

There is a balance to be struck between the desire to achieve maximum efficiency from a smaller unit and minimising the time your heating is off while the DHW cycle is going, especially in the depths of Winter, and taking into account regular defrost cycles. My son's passivhaus is 150sqm and the heat loss calcs suggested a 5kW ASHP but he went for a 7kW ASHP so his DHW tank would heat up quicker for a family of 4 regular hot water users. A 200 litre tank if heated by a 4kW source would take 1 hour and 45 minutes to get from 20 to 50degC. 7kW brings that down to under 1 hour. My view, for what it's worth, is that you should go for a minimum of 6kW, because modern heat pump software manages the system to avoid cycling and maximise efficiency no matter how oversized for central heating purposes, up to a point of course. Case in point - I have an 11.2kW heat pump which is at least 50% oversized but is achieving SCOP of 4.2 with a microbore fed radiator system. And my hot water heats up very quickly!!!

15 MAN days, i.e. one guy for 15 days or 15 guys for one day

http://www.cool-info.co.uk/multi_dx_systems/Multi-split Systems.html This appears to show five different setup variations based on a common central heating style flow/return rather than individual dedicated flow/return lines

not forgetting this very important piece of information. Could reduce heat loss by 25% - 35%, so 7.6kW heat pump could be reduced to only 5kW - 6kW

peak heat loss of 70 watts per sq m, times floor area 100sqm, = 7,000w heat pump required

check that all the gate valves (usually circular red wheel handles) are fully open, both around the domestic hot water tank and and loft tank, and if you don't have a loft tank then the Event XS will not work.

Turn off the power to all the indoor (FTC and main control panel) hardware. Turn off the heat pump isolator switch. Wait five minutes. Turn back on the indoor controls, then the heat pump. Wait till the FTC control panel has powered up and is in reset mode (blank screen) then press the on button (far right on my FTC)

Have you tried powering down and back on again? Sometimes changes are not detected until you do this. Also could this video help - includes remedial steps you may be able to do yourself

Did you power down completely before changing settings (or at least power off/on after changing)?

Could it be that the dipswitch setting you changed only controls the internal unit, and the external unit has its own separate dipswitch (or other) hardware settings which need to be changed to cooling mode?

Definitely no compressor cycling there, job done.

Apart from the power graph you showed earlier, can you see a smooth flow temp line? On mine this is the graphic which best shows the compressor either switching on and off, or running continuously

Too little info so far. The energy use data you gave is way too rough even for a ball park sizing estimate so, as things stand, your heat loss calc is your best guide.

Do you have an auto mode? If so might be worth trying. On mine it makes a HUGE difference to the operation in the shoulder months. Although my HP is at least 50% over capacity, in the shoulder months the compressor always runs continuously at no less than minimum power for no less than 20 minutes, so typically, in 40 minute cycles the flow temp curve rises and falls between 30 and 40, with the pumps running continuously. Last year I changed from WC to auto mode; in Sep last year in WC mode the COP average was 3.6, and in Oct in auto mode the COP was 4.2. Previously in WC mode I could see the compressor switching on and off every few minutes trying to maintain whatever constant flow temp was determined by the WC curve.

How would you define short cycling in this case?

What's the total

Is this an existing or new property and, if existing, what is your annual energy consumption on heating, in kWh?

any possibility that you might extend in the next few years?

Here is the new (beta) service from Bucks CC. Includes a section on heat pumps. Quite easy to use. https://editor.planx.uk/buckinghamshire/find-out-if-you-need-planning-permission/published

The MCS database may be helpful, giving SCOP test results at different flow temps (typically 35 to 55) for most (possibly all?) commercially available MCS certified heat pumps, now including the new Octopus Cosy 6. https://mcscertified.com/product-directory/ While accepting that design and operation mode are most important, it is worth noting that, generally, the MCS tests show that R32 heat pumps have significantly better SCOPs than their R290 equivalents. You can see this most clearly by comparing like for like R32 vs R290 models, for example the Misubishi R32 6kW model PUZ-WM60VAA has SCOP of 4.81 at 35degC, compared to the Mitsubishi R290 6kW model PUZ-WZ60VAA (a much newer model) which has a SCOP of 4.39 at 35degC