JohnMo

Move to octopus they have better smart tariffs, are a better company to deal with, use the forums referral scheme and get £50 credit. Your tariffs will also have a peak rates, so you need to understand how you use energy and work out the best one for you

Our house sounds a similar build, we have lots lots glazing 192m² and we have 4kW heat pump. Your calculations sound in the right ballpark. Do not over size, you will take an efficiency hit. important to look at min modulation at around 7 to 10 degs, you basically want to output half your design heat load. So about 2kW in your case.

Zero idea why you would need or want a buffer. Other comments as per @Dave Jones.

The operators don't seem to understand the process. You have to go through a dedicated part of the website https://octopus.energy/help-and-faqs/articles/export-without-mcs/

I just paid the £250 will break even in a year and still way cheaper than a mcs install.

Pretty sure the word "new" wasn't there when I made the comment

Your thread title is incorrect - renewables didn't meet all the World's new electricity demand in 2025. Renewables met demand growth (which is different) while fossil generation stalls, i.e doesn't grow. The grey section is still fossil fuel generation.

Why do it correctly, as Chofu intended

If from heat pump, there is zero need for a mixing valve or additional pump. What Grant heat pump? The R290 has a modulation circulation pump so it will modulate flow rate to match demand - but doesn't do cooling ever, as no option available. R32 will do cooling but not if installed as per Grant instructions.

CCTs provide hydraulic seperation - are you doing a mixed radiator plus UFH system?

It isn't a combi, it effectively has a thermal store or UVC, within the enclosure with a heat pump.

9 a locking mechanism - not really novel. 10 mesh grilles, been used in industry for years to prevent small fingers and animals away from things they should not touch 29 plenty of people have installed a DHW cylinder in a shed outside 30 a modular enclosure novel - no 34 - 36 Here something someone invented about 11-12 years ago - Unical Gas boiler version ASHP version

Sound like the patent basically covers having a dwh cylinder of any description in box or shed (enclosure) with gshp would be a contravention of the patent. Which is nonsense. Or containing a buffer vessel in the heat pump enclosure and they exist already, would contravene the patent. Good luck to the company, but the patent is a little limited.

Our last house was 1830 build, solid stone, very similar to the the linked house, we were NE Scottish town not rural, ours 3 storey build similar size, a lot of big single glazed windows, if I lived there now, knowing what I know now, would have zero issues installing a heat pump. Would get a better CoP there, than I do here, as we used to heat nearly all year, if fact the heating was never actually switched off (available 365 days a year). We had a similar sized boiler and it was run at a reasonably low temp and on 24/7 with very little setbacks, the boiler just ticked on and off as needed.

What is the innovation - a high temp small cylinder with mixing valve outside within the heat pump enclosure? Or did I miss something? Is it something like a heat geek mini cylinder just outside instead of in a cupboard?

That's misplaced logic. If your export limit is 3.6kW and you produce 3.6kW for one hour that's 3.6kWh assuming 3.6kW is exported. How does that work, assume 12 hrs a day at 3.6kW output, so 43kWh export. To get that would be nice. I must have better things to do on a Sunday, than answer this rubbish.

Why that big? But when is that likely to ever happen. If you hot water is above 40 degs, you will be adding cold water to flow of the showers as well... Think you may be loosing the plot!

You've lost me?

If that's the plumbers handiwork, find a new plumber.

2x filters, and paying for someone to it if you can't.

You're flow rate is determined via building regs, however you will most likely to reduce through put to meet passivhaus standards, otherwise a big house equals very low humidity levels. 1 or 2 units, I did two for ease of duct routes and reduced duct length. So location is in very different places for best routes of duct. But you have twice the maintenance bill. So a balance for you to make.

Wouldn't get to bogged down with that. If room temp is 20 and you have UFH, then your minimum return is not likely to be lower than house temp (assuming you have insulation under the screed etc). If you are operating a flow to return dT of 5 you minimum flow temp will be lower than 25. Most R290 will go down to 20, some may be limited to 25, but they are mostly R32.

I would try to find the engineering tables for various heat pumps, the minimum modulation figure is more important than the max output figure as your heating requirements are around half your design day for the average heating season day. Plus you will get an idea of expected CoP at you flow temps.

Isn't that the current situation in Scotland loads of wind, hydro etc, almost zero electric comes from gas, but unfortunately our pricing is driven by English policy. In fact SNP use that as a reason for independence.

Lots of panels on a G98 inverter, massive overclock is the way to go. Easy no permission needed, just a G98 notification. Self consumption is fine in theory, in practice difficult especially in the summer, you just end with loads of hot water you can't use. Just go with Octopus and pay £250 and get the export (wish I did it 3 years ago), East Suffolk you will generate tonnes of energy even with a 3.68kW export limits. My advise, self install as many panels as you can to stay within the max voltage limits of your inverter, it's cheap, spend £250 to get with octopus. Export everything you don't normally consume.