G and J

Ideally you need an enthusiastic sole trader sparky.

1). If I run my ASHP UFH 247 then screed thickness will have no effect on performance and I’ll have reasonably constant room temperatures. 2). If I run the heating a bit harder but only in the cheap periods of a ToU tariff like Cosy, I will save money but the room temperatures will vary more than in 1). above. 3). If I have a deeper screed then the room temperatures will vary less. Is that correct?

Oh it must be true then. Was the next article DIY battery install? You know, the one that linked the blog about rebuilding after a house fire lol Being serious if one can buy the bits that cheap it might not be long before complete ‘plug in’ packages get to sensible money.

So £3k (exc. vat as I’m building a new build and can claim it back) all in with battery rated at 3,500 cycles, which means it is likely it would be good for more than that, a lot more if you are lucky. Using the Nirvana figures above £3k is equivalent to 20,000kWh at 15p saving per kWh. At 16kWh per day payback that’s a ~3.5 year break even. Getting warmer.

You are a very bad person @JohnMo! (Sorry!)

Found it! https://www.fogstar.co.uk/products/fogstar-energy-15-5kwh-48v-battery?variant=41607893876795&country=GB&currency=GBP&utm_medium=product_sync&utm_source=google&utm_content=sag_organic&utm_campaign=sag_organic&gad_source=1&gbraid=0AAAAADdkPQNr_gr7TdOVsH8qb_ItWShjf&gclid=EAIaIQobChMIk8vFmZiGigMVwJtQBh340gUqEAQYASABEgJlKPD_BwE Can one of the grown ups add the cost of an appropriate stuff and inverter and gubbins to make it a complete thingy? (I’m assuming it has to be an ac coupled battery to do the job).

When I looked at this it seemed really attractive. But then I thought, hang on, if that kind of storage and resell type system paid in then in no time we’d see farms of batteries springing up all over the place, trading on an increasingly tight margin. Thus market forces would depress the margin perhaps to the point that it becomes irrelevant fir the domestic battery owner. I accept that in the short term it might work, but the paybacks are v long term at the mo.

Link away, and save me fruitless searching….

Payback calculations are, in my experience, often very difficult to nail down to a high level of confidence. And payback is only break even. An investment decision usually wants to see profit in return for the risk. The risk of future ToU tariffs having a smaller differential (which is what I think of as your ‘less generous’) ‘feels’ small to me. Growing national solar capacity must be driving an ever increasing differential in generation cost and ToU is all about demand shifting. In this instance though I think there is significant technology related risk. 9 years is a long time for a battery. That’s over 3,000 days, so presumably at least 3,000 charge/discharge cycles and some ToU tariffs have three low periods a day. How does a 9 year old electric car perform? Are there many that last that long? Those that do won’t have the same range they started with. How reliable are the charge/discharge efficiency figures you are using? Is it something like 100Wh in for 90Wh out? What’s your cost of capital? Current deposit rates are circa 3% so that’s a minimum I guess. The ToU tariffs I’ve looked at charge more than standard for some periods, which also needs to be factored in. What is the probability of the system working without needing costly repair for the time needed to payback, (let alone profit). How much will a battery system be in the future? Say two years time? I’m guessing less. But…. often a good way to kill an idea is to assume perfect everything, and if the results are either crap or borderline then no further work required as it’ll all be downhill from there. A sub 9 year payback requires 16kWh totally battery provided (there are multiple cheap rate periods and usage is perfectly distributed so battery never runs flat) at 100% efficiency, and zero cost of capital and no repairs. I think in reality it’s an unlikely best case break even over 15+ years unless ToU tariffs significantly increase their differential. Sorry. However, it’s still ok to do it if it feels good. Maybe power cut cover appeals (which it does to me) or you accept you are gambling on future tariffs being more advantageous. For me it’s a ‘wire up ready but wait till prices drop’ thing. Though I keep watch.

As we are thinking of using an insulated beam and block floor that’s a really interesting notion. So instead of a screeding team (is that what does screeds?) it’s a concrete lorry and a rake…. So the rest of the build happened off of the finished floor level….

And in winter the ducts will be warmer than the loft in our cold loft….. ok, condensation panic over.

Did that make it cheaper then? (He asked, aware of how much he doesn’t know….)

Looking like our 5kW heat pump will be needing to provide less than 2.5kW heat load at max (normal) temp difference if we don’t light the woodburner. Intuitively, against the various discussions on here, that feels sensible. Of course one piece of info that’s missing from my jigsaw puzzle is cost of screed. When I google I get handwavy £18 to £20 /m2 but no info as to how thick that figure refers to. Will there be much difference between 75mm and 100mm fibre reinforced screeds? Is there a budget rule of thumb I can refer to?

Hmmmm. I’ll have a vcl directly below my bottom level of fluffy but I’m now thinking condensation risk when on summer bypass…. Goodness it boils the brain!

If you are M is JohnMo really Q?

I am sooooo 20th century. Sigh. I guess the best representation of my ideal level of automation is the kind of clockwork plug mounted timer that turns the fairy lights on just outside our rear kitchen doors….

Ah I see, thank you. Using these would mean using rear supported backboxes, so they won’t work for me, so I’ll stick to the normally Appleby type dry lining boxes and I saw some cardboard jobbies to stop the backbox filling with pug on here which I though were a brilliant idea.

Oh my word my worst nightmare!

Can you have a normal rocker (i.e. on/off) switch with Loxone?

What are they called? I wanna take a closer look.

I’ll have no. 1. for our installation please. As far as possible we want a fit and forget type cosy heating system. Can I do that alongside using three cheap rate periods of heating?

Good grief there’s a warning for me. I’ll be running ducts in the loft and had intended to run on top of the first level of fluffy stuff, underneath a couple more. Ok your 100mm of PIR is more insulative than our 100mm of fluff (technical term!) but still, methinks I need to rethinks….

Oh dear. We’re screwed.

A source of much head shaking over the years. I plan, I measure, I calculate, I re-check obsessively, then J walks in and shoves it a little to the left so it looks right. Sigh.

Crumbs, I assumed pre apps were universal. I believe pre apps were an attempt to regularise and frankly, reduce the ‘would you’ enquiries that planners used to discuss. So if they’ve not done that then surely they should talk to you about what they will allow. There’s a lot of knowledge on here. You could share location and pictures and get the folks to comment on what the planners would go for.