@wh0am3ye - welcome to the forum!

You appear to have grasped the basics cleanly and quickly, well done.

To answer you first question, the Halo or any room stat for that matter is largely redundant as a thermostat, instead we use it as an on /off control. A bit counter-intuitive, but think of setting it to 30°, as you have, is one way of setting it to be (always) on (unless you also chose to have a setback, see below).

To answer your second question, I'm not familiar with octopus's ToU tariffs but I definitely do use setbacks and the way we do this is as you say set the room stat (or whatever control you use) to something a bit lower than your desired room temp. This then becomes 'always off', but with a backstop, if the room temp goes below the setback setting then the heating will come on. Your proposed schedule where you have the room stat setting set low during the peak hours will achieve exactly what you want, the heat pump will be off during the peak hours, but will come back on when you want it to. You may need to tweak the set back temperature setting a bit, to make sure the heating doesn't come on during peak hours by setting the setback a bit lower.

The key point is to recognise that you are not using the room stat as a room stat, but as a timer. In effect this timer just happens to use the room temp setting as the 'trigger' to decide whether the heating should be on or off.    

Keep turning the weather compensation parameter compensation parameter down until the house is at the right temperature for you.

Once that’s right you might need to add in some room influence and set the upper limit to ~22C to allow for solar heating at this time of year since if you’ve got south facing windows it could be the cause of the overheating.

I can’t answer the timed-controller question but it sounds logical.

Do you have a buffer tank? Is it piped as a 4 port (2 in  out) or a volumiser (2 pipes, one in one out)?

Welcome to your new hobby!

Hello, well it looks like you have made a good start, there is an art to setting up periodic use as well as weather curve as you have to calculate or work out the recovery time, remember ASHP are looking to use the building fabric as a heat energy storage battery this is why they work so well as low and slow 24/7. You will need to consider seasonal heat loss, TOU tariff schedules and comfort, solar gain and so on for example, your recovery time will be shorter in spring than in the dead of winter. However there is a complete solution for this to save you having to do it manually, there are now many 3rd party software applications that can be added to quite a few ASHP brands, "you will need to do a bit of research to see what you want and which fits to your brand of ASHP" For example Haven Wise or Homely can interact with your, TOU tariff, weather curve, periodic us, seasonal adjustments and many other factors.

Some of the 3rd parties claim that what they cost can be off set in savings, I like to think that its more valuable in the fact that it works it all out for you, some of these 3rd party interfaces also allow your installer to have a back end so if the system has a problem they can remotely log in and take a look, perhaps saving you a call out fee once the installation warranty has finished.

With regards to the overall heating at 20 being a bit warm for you, rather than just reducing the weather curve you could also reduce the target flow temperature, for example, if the system was designed to run at 45 deg C flow temp to reach 21 Deg C room temps @ -3 you could set it for 44 Deg C target temp as this will reduce the output slightly based on your emitters and in turn should deliver a slightly lower room temp target. Note: if you change the target flow temperature it may effect the final room temperature more in the height of winter at -3 deg C but probably only slightly and you could always turn it back up that 1 deg in for the winter.     

I hope this is helpful.

Thank you for your responses.
I think for the time being, I will manually adjust the desired temperature during the peak window, just until I get the WC curve set correctly. I'll be sure to keep an eye on the recovery time of the temperature after this evenings peak window to see how I can maybe use the timer in the future. I moved the WC curve down to 0.3 this morning as we settled at 20 degrees overnight, much better than the 21 the night before, but still far too hot. I shouldn't have to sleep with the windows and door open in March! 🤣 

I also took a note of the heat pump compressor starts this morning, to get an idea of how many cycles we're getting - picked up from another thread I was reading.

@judith  - I don't believe we have a buffer tank. We do get some solar gain in our kitchen diner, which also happens to have 2 large 3-panel radiators. I imagine I'll need to adjust the locksheilds on these in the future, but I'm holding off for the time being as it's a 1980's extention with large windows, in comparison to the rest of the house which is an 1850's Welsh stone cottage, so thick walls and small windows!

@ashp-bobba I've had a look at Havenwise and Homely, and sadly, neither supports Ideal Heat Pumps yet, so I will keep a look out for one that does, as they certainly seem like they would be helpful!

Great progress so far, keep going you’ll get there! Your Welsh cottage part will have a very long thermal time constant, as you probably already realise, but your large kitchen diner with big windows will cool off quickly as you try to coast the peak electric. But if you’re cooking despite the peak it will compensate.

Our pump had about 6 cycles today in the 22hrs so far, to give you a comparison.