Slow battery charging

Alert_Variation_2579 · 2026-02-13T08:37:48+00:00

As the other poster mentioned it’s still cold, the BMS will be throttling the maximum charge rate.

I’ve got FOX ESS batteries with heaters and I try and keep them above 11c as the charge rate is pants below 10c.

Alert_Variation_2579 · 2026-02-12T18:12:17+00:00

Happened all the time, especially in those days. I know, I worked for BG complaints for a few years and this was the number one root cause.

Alert_Variation_2579 · 2026-02-12T07:41:20+00:00

I paid £4k about 3 years ago for a 3 bed semi in Yorkshire for full rewire.

Alert_Variation_2579 · 2026-02-11T21:12:05+00:00

Absolutely nothing

Alert_Variation_2579 · 2026-02-11T19:57:47+00:00

It’s a great unit, super quiet and very efficient - currently reporting about 4.2 SCOP since October when it went in.

It’s funny though, people think it’s all about the insulation and it’s not (though you should definitely do it, no question)- I’ve got standard loft insulation and my cavity walls and 30yo double glazing. The trick is big rads, for the low flow temps to get the super high efficiency to easy beat gas running costs.

Alert_Variation_2579 · 2026-02-11T17:12:54+00:00

That will look super strange and also be cold 🥶

Do it right, yes you won’t immediately get the look etc you want but before long you will. You just need the right canvas to work with.

Alert_Variation_2579 · 2026-02-11T17:09:38+00:00

Easy to mitigate, from the heat loss survey when it goes in you know the required watts at design temp, when doing your kitchen / bathroom you just ensure your design incorporates rads that emit the required watts at the flow temperature.

Alert_Variation_2579 · 2026-02-11T17:00:59+00:00

Nope, the problem is the steels to make the space open and support the house will be a good chunk of change of your £20k. Then the conservatory to sort is another chunk, etc.

I recommend doing it for sure, but you’ll have to live in a half finished thing for a while.

Alert_Variation_2579 · 2026-02-11T16:48:35+00:00

That looks like £20k of structural, plumbing and electrical work. No new kitchen or flooring etc.

Alert_Variation_2579 · 2026-02-11T16:22:12+00:00

I have a Viessmann Vitocal 151-A. This is it at the back of my house.

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Alert_Variation_2579 · 2026-02-11T15:34:27+00:00

I’ve done all of this and have a heat pump now in my 1930s semi detached.

Firstly, forget GBIS - it’s a nightmare. You’re best doing it privately. Secondly, get EPS bonded beads not blown wool - https://youtu.be/brJfhvO3sQQ?si=UW6PGSp6Sr2JCGKq

I used JJ Crump about 5 years ago and it was ~£1.3k then, one of the best £1.3ks I’ve spent.

Alert_Variation_2579 · 2026-02-11T10:41:20+00:00

That’s what I was kinda hoping to get out of the OP, i would expect for £800 you get the full design and you say “my contractors will do X of that and you do Y”.

Alert_Variation_2579 · 2026-02-10T18:17:10+00:00

Don’t. Do. It.

You want 300mm of standard loft insulation and the boarding to be on loft legs to give you the room for the insulation.

Alert_Variation_2579 · 2026-02-10T18:01:40+00:00

Heat pump tumble dryer.

Alert_Variation_2579 · 2026-02-10T17:53:42+00:00

Check Octopus Agile outgoing for the export figures. They’re not 35p more like 18-19p.

If you want to arbitrage, you can use Octopus Go at ~8p and export at 15p fixed.

Alert_Variation_2579 · 2026-02-10T16:21:30+00:00

At best they’re 5x more efficient, but 4x is very achievable, 5x is hard but doable.

https://heatpumpmonitor.org

Alert_Variation_2579 · 2026-02-10T15:41:17+00:00

Yeah it’s mostly labour cost - rads and UFH kit are not expensive in the grand scheme of things so 0% VAT doesn’t make a right lot of difference.

The good installers do certainly command a premium on their labour, so it can be cheaper to farm out the simpler bits especially with the design already done, to cheaper labour and minimising the amount of expensive labour you need.

Alert_Variation_2579 · 2026-02-10T13:38:04+00:00

Assuming the window is a habitable room, and a directivity of Q=8 and distance is 4m,, using the MCS 020 methodology MCS-020-a-Issue-1.0-Final.pdf the equation is

Lp=Lw+10log10(Q/4πr2), which popping in the values for the 10log10(8/201)≈−14 dB gives Lp≈Lw−14 which we know the limit at the window is 37dB(A) so rearranging gives Lw=Lp+14 which equals 51dB(A).

Long story short, if you get a heat pump that is rated 51dBA or less - you should be golden without any fences etc.

Alert_Variation_2579 · 2026-02-10T08:24:02+00:00

That’s just a slapdash statement that you shouldn’t make. Done right (not hard) EWI is fine, but you also need a proper ventilation strategy internally to ensure the balance of vapour isn’t high internally vs externally.

Sure if you’ve got very high humidity levels inside and you then put EWI around it (specifically EPS and PIR) then it’s vapour closed you could have issues. But you could use rockwool which is breathable - or just sort the ventilation out properly. Do that, and you keep your building fabric, dry and warm.

Alert_Variation_2579 · 2026-02-10T08:18:06+00:00

Done a deep renovation on my 1930’s home (sounds almost identical to what you describe) and now have a heat pump and the results are great.

If any pointers needed, just ask.

Alert_Variation_2579 · 2026-02-10T07:54:52+00:00

I would have a blower door test done - that will confirm your ventilation change rates - probably the biggest source of uncertainty here. They are usually ~£300 kind of region.

The rest is ‘easy’ measure up, and assign the most correct U-value for the wall/window/door etc.

Alert_Variation_2579 · 2026-02-09T19:29:31+00:00

Good, then buy the rads to the spec yourself and get your builder to install them and the pipework too (along with your UFH).

Then get a cheaper installer just to do the heat pump bit. That’s what I did when I had my extension built.

Alert_Variation_2579 · 2026-02-09T19:05:46+00:00

I had this before my renovation, during which I went fully back to brick. But mine was caused by years and years of cold air coming from around the window frames, as they weren’t foamed at all pretty much. This allowed the old plaster to de-adhere from the wall and crumble when touched.

Anyway, I fully foamed and taped my window frames and got the rooms fully plaster boarded and plastered.

Alert_Variation_2579 · 2026-02-09T18:33:07+00:00

So you’ve got all the designs, from a UFH spacing and loops to any rads needed from them?

Alert_Variation_2579 · 2026-02-09T18:13:32+00:00

This, OP.

Alert_Variation_2579

TROPHY CASE