G and J

Is that to save money on inverter sizing/purchase cost and thus accepting some lost Solar power on the sunniest of days?

And that I think is my base case against which other scenarios are compared.

May I ask what the electricity unit rate you are using in that calculation ? (And PS I’m sorry if I’ve given you a headache lol) At 6 years payback I’d be tempted. Also, am I correct in thinking that one has to have an MCS approved installer to get a FIT?

Hmmmm, interesting notion, the heat store, will ponder, but suspect that finding space for a sensible sized store and the extra plumbing complexity may make it less attractive. I've just looked up the Octopus Cosy tariff and a heretical idea has popped into my head. Suppose I arrange things so our system does all its heating and DHW, washing machine and dishwasher usage, etc. within the low periods. Does that mean my payback for solar pv becomes 30 years or so? Not having solar will mean I miss out in free hot water but if that’s in reality the only thing on that side of the balance sheet then is the investment justifiable?

The area of our south facing roof limits us to circa 5kW of panels, and as we are both retired we are often around during the day, so maybe batteries won’t be on my list. But another research topic now added to my ever expanding list - TOU tariffs.

Interesting. I’ll re read that a few times and try and get my head round it. Our current thinking is that batteries have a payback period of circa 10 years, just based on some fairly broad brush calcs. At that payback we will wait until after we know exactly how much our build will cost overall before finally decide to add batteries or not. I appreciate that it’s a ‘how long is a bit of string’ question, but what sort of payback period do you feel you are looking at for your batteries?

Are ASHPs ok if they are turned off for a few months? I like the notion that the ASHP isn’t running when I’m quietly snoring in my hammock a few yards from it, plus I wear out a cheap immersion element rather than expensive fans.

I’m just starting to get my head round how the Solar PV systems can work. Am I correct in thinking that in this instance if the batteries are full and there is excess solar power compared to ambient demand, then the Eddi will dump the spare power to, say, an immersion heater rather than just dump it back to the grid?

Play nicely you two or you’ll be sent to your room. 😉

Thank you. We will definitely be using these.

A legend in what sense (he asks with some trepidation!)?

It’s great that you installed two of em. but do either of them work and continue to work? (Goodness I can be sooooo pedantic sometimes lol) In truth I’m trying to avoid giving myself a maintenance headache.

Without the layout it’s kinda difficult to contemplate - May we have a diagram?

Crumbs. So far so good. Maybe I should believe the marketing.

Hi all. Slowly working through my humongous list of don’t knows in advance of starting detail design. One thing that’s troubling my cynical mind is the use of things like: https://www.plumbworld.co.uk/geberit-1120mm-duofix-frame-delta-concealed-cistern-and-delta20-flush-plate-round-buttons-2255-1274020?utm_source=organic&utm_medium=shoppingfeed&utm_campaign=googlebase&gad_source=1&gclid=EAIaIQobChMI_9vTy4CVhgMVI4hQBh0-lg1BEAQYDCABEgI9CfD_BwE I have searched for goods and bads and haven’t really come up with much. I’ve watched the vids which claim to demonstrate that all necessary maintenance can be done through the hole covered by the chrome plate that surrounds the buttons. We’re having wall mounted potties mounted onto studwork. Anyone had good/bad experiences with these that are happy to share I’d be grateful.

Our plot is about half the width of yours and we have in our planning consent a gym/workshop of about 21m2 internal at the bottom of the garden. We too will be building close to each side boundary. We did briefly consider building the workshop first then trying to live in it but felt that it would be untenable living next to a building site that blocks access to the street and thus will be difficult to safely get through. It might be easier than it first appears - any relevant experiences that might help understanding of the feasibility of living on a tight site?

Guess who didn’t realise he had to follow the topic to get alerted to replies! D’oh!

Sorry for the delayed response. New build. Attached garage out front and that’s where the MVHR unit will live. I’m thinking big rigid ducts to centre of house and smaller ducts radiating from there.

How did the overall cost compare with the quotes you may have got from design/supply/commission type companies? I’ve sent in our plans and had a couple of quotes and the intensity of marketing tells me there’s likely to be a nice profit margin built in to their process. However when I do some ball park ‘buy the bits myself’ calcs the answer is reasonably similar and that’s without a professional design.

OK, I now accept that there really is no such thing as a free lunch. I can’t find sound data on the Activair unit, which should in itself tell me all I need to know. A totalhome 300litre water tank with integral 0.43kw ASHP (HPW300) generates a sound level of 55dBA at 3m and has 160mm ducts and half the power of the Activair unit. A Samsung 5kw monoblock ASHP generates 45dBA at 1m, less than an eighth of the sound at a third the distance. Back to plan A methinks. (I’d be grateful if I’m wrong and someone corrects me, mind). But it’s good to explore options…. 😕

Thank you Steamy, although I can’t pretend I really get those numbers I do understand that such a unit would need to draw its air from outside to work, so I’m no longer contemplating a connection with the MVHR unit. So it using direct air means no efficiency advantage over an external monoblock ASHP methinks. However it still has cost and convenience advantages potentially for us. But, worryingly, a hunt around the net last night (guess who couldn’t sleep) yielded no noise figures, and given Steamy’s numbers I’m wondering if the unit will end up sounding like a chip shop extractor when running due to required air volume, which would not make for happiness.

Our plot is 24’ wide, and we’re building in pretty much the footprint of the bungalow we will be demolishing. We’re too close to each neighbour to have an ASHP either side, and we’re not keen on it being our most prominent frontal feature. We also don’t want to sit next to it on our patio out back, so we’ve shoved it 10m to 15m down the garden. We’re building an attached slightly oversized garage at the front of the house (to keep our campervan snug plus it looks ‘right’) which will be half the width of the plot and that’s where the MVHR is hopefully going - intake on one side exhaust on the other. Ditto this sort of unit, if it ticks all the boxes. Otherwise it’s a remote monoblock ASHP amongst the daffodils.

I’d never heard of them till I saw JohnMo’s link. Yes, now you point it out I can understand that the MVHR will (should) only deliver a low volume of air and in winter it’ll only be slightly warmer than the outside air anyway. So forgetting the MVHR link, if there’s space inside (which I have), this looks an attractive option. Especially compared to my ‘half way down the garden mono block ASHP’ plan. I can’t help thinking I’ve missed something here?

I’ve a horrible feeling I’m going to make myself look really dumb here, but…. We’ve just got planning permission and we are about to start serious designing/decision making with the help of our architect, (hence spending nearly every waking minute with nose pressed to this forum). I don’t have a heat requirement figure yet. Have spoken to an MCS person who has impressed me with his common sense and the simplicity of solution he has outlined, i.e. UFH and DHW run from “small” 3 to 5kw ASHP in garden. But, if I’ve understood it I could put a unit like this literally next to the MVHR unit, and not have the unit in the garden, maybe get even better efficiency by using exhaust air, and save myself capital too. If so why does anyone have an outside ASHP?

I’ve explained my question poorly, apologies. Let me try again forgetting anything solar. How many months of the year am I going to run my UFH?