oranjeboom

Thank you Mr Harris! As simple as that then. So then it comes down to how much heat is pumped out to the UFH which will be dependent upon UFH temp setting, duration and heat loss? Wunda indicated the following for my setup which was based on 'current BuildRegs': Groundfloor: Water volume: 129L; Estimated loading: 9.45Kw Upstairs on separate manifold: Water volume: 25L; Estimated loading: 2.03Kw Not sure how they calculated the above, but how would I size a 12kWh SA unit for my UFH? My floor heat loss is: Is that per sqm?

I was quoted for a 2 12kWh UniQ Heat units for space heating (and a 9kWh UniQ eHW for DHW charged by 3.8kW PV) and that is with double your heat loss: I will have 180sqm (135sqm downstairs) of UFH to heat (with an ASHP) but suprising that you also have been quoted for 2 units @Triassic! Over-specced in your case as only half of my house is 'new-build'. Yours will be more airtight than mine and you also benefit from large south facing aspect iirc. It's a lot of money especially if I have to add on the ASHP also so I'm thinking to just get one 12kWh unit for space heating and see how that performs over winter. On those days that I see -temps I could just plug in some electric heaters if necessary. If I do find I need another 12Kwh cell, then I can always fork out later for one. Haven't read all the SA material I have been sent tbh, but wondering how long a 12kWh cell takes to charge using an ASHP? If it's being charged overnight ready for the UFH to kick in say from 5am in the morning for a few hours, then recharges during the day for late afternoon/evening demand, would a single 12kWh cell struggle to do that? I'm probably not being logical at all with my thinking there.

Looks like I will have to make some as the std sized ones will be too small again: 12mm pb / 25mm batten / 100mm Timber SIP wall / 25mm batten / 12mm pb so will need approx 180mm door lining.

Thanks all! Looks like I'll go for a 'std' size then. @PeterW Todd's have no supply at the moment but I'll maybe pre-order them now with some of the other doors I will be needing. Anyone have a voucher code for them?? ? Have a similar situation in one of the vaulted rooms so will check whether I can get a std size in there also. Door lining kits - I've read that some are woeful (e.g. Wickes can be a mixed bag of warpiness). Any decent online suppliers?

The extension is pretty much the other side of the house so no direct comparison of differing door sizes. There is a distinct junction between the old and new anyway as the 2.2m ceiling will curve up from the old house into the new house where it's 2.6m, so not too bothered about people noticing the 'old' vs' new' part of the house. But yeah, agree that it's easy enough to do. Just not sure why architect left them so tall - could almost put a window above the doors which we quite liked in our australian house which gave the hallways a lot more light.

Rightio - about to plasterboard some more rooms but not sure whether to adjust the current door openings (2200 x 930) or leave as is and get chippie to source doors that will fit that size. No idea why architect went with that size bt, but then he often just 'assumed' measurements and this is one I did not spot in time! Door linings will obviously reduce that opening by a bit, but not many online places seem to do doors taller than 2.1 metres. Also leaves me very restricted in their range of doors and i really don't want to be forking out more than £150 for a customised door. Does anyone know of places that do doors above 1980mm? Ideally I am after a panel door like this: or like the one below which goes by various names (Mexicana, geneva, cottage oak...), which @JSHarris and @PeterStarck went for: Again, pretty std at 1980mm. I suspect that it will be cheaper to adjust the openings (in the timber framed walls) to accommodate a std door size, but would really prefer taller doors to 'suit' the higher ceilings (2.6m). I think I've already made up my mind to just got for std 1980 size as I'll be limited in getting ready made door lining kits also....unless someone has a source for a company that does do customised door sizing at a reasonable price?? OB

Sorry @MikeSharp01 - last gas guy I used ended up in prison. Not sure if that was due to his workmanship or some other kind of 'handiwork'.

@Stones 174sqm and it's an uneven H-shaped building. Not too worried, just trying to get the right level energy in there for the winter months for the UFH and DHW, i.e. don't want to fork out for a 12kW ASHP if I can get away with an 8kW machine (30% oversized for January temps when I'll be needing 70kWh per day for space heating and DHW. Likewise, I don't want to go in undersized either! Funnily enough, just been reading the thread you started o ASHP sizing: here. Thanks Dave.

@vfrdave Is your's a newbuild Dave to passiv-ish stds or a renovation? I've just completed my heatloss calcs and I have ended up with 4799W (-10 outside; 20C inside) which is a lot higher than I was hoping (with 300mm insulated slab, EWI, 3G windows, SIPs). So now looking at what other areas I can improve on to maximise efficiencies (using up all my leftover celotex where I possibly can). Let's just be grateful that the OAT isn't often -10C!

18C or Wendy's 24C? Bet you have to drink it fast before it evaporates!

Thanks. Yes, i have lots of S facing glazed walls which will help a bit in the winter but potentially overheat the place in summer (although the sun is already nice and high now to reduce that by quite a bit). Cell34? I can see that B27 incorporates window and door areas values, but I don't see anywhere in there that you can list all of your different walls with respective u-values: So you have to work out your average wall area first and enter that in B7:

Right, so I've started playing with Jeremy's heat loss spreadsheet and have started going over my figures to see if I have screwed up somewhere big time, as my heat loss seems a bit high. So, I have a number of different walls of differing u-values (column D) with respective % of total wall area (E). I have then mutliplied each u-value with that % (F) and then totalled the figures in F to get a final u-value. Is that an accurate method of dealing with differing u-values? TIA!

I may be! But I do realise that getting a renovation airtight is cumbersome with the end result often being way off PH levels (0.6 ACH) and I recall reading somewhere, that one is lucky to get a figure of 5.0 which I believe was in ACH. Lots of articles appear to use ACH and m3/m2.h interchangeably which is probably to do with BR's that use the latter and everyone else use ACH! But yeah, my figure of 5.0 is way too pessimistic - wondering what renovators on BH typically get? May start another thread on thatas I don't want to diverge from Jeremy's s/s.

Thanks @PeterW, @Alphonsox Updated the s/s. 6.8KW/h so 163KW/h per day!!? Time to re-check my calcs! Biggest issue is the ventilation loss. Anyone been successful recently in finding the localised temperatures recently from the metoffice site? Had a look yesterday but could not find them, so just kept Jeremy's figures in there. Not that my local figures are going to reduce my space heating demand significantly!!

@JSHarris Just resurrecting this thread as I'm finally biting the bullet and have downloaded your heat loss spreadsheet from your site. I know that's what you say, but do you have a dummies guide in completing it?? I've got most of my measurements and figures to hand so have had a go and completing the s/s, but have a couple of questions: 1) Should B23 be referencing B21 also? i.e. =SUM(B19:B21)? Or is floor area heat loss incorporated elsewhere? 2) "Fabric & Ventilation loss" sheet has Internal wall area on row 19. Presume this is essentially all perimeter walls including windows /door areas? 3) Lastly, looking at the table 'Heat loss vs OAT' gives me heat loss at various temps. So where there is a difference of 20 degrees, I get a 'Total heat loss power (W)' of 6809 (don't choke there!!). So essentially that is my heat demand for space heating? I've set current ACH to 5.0 (this is a retrofit after all) but hoping I can achieve a better figure than that as I continue to methodically seal areas as best I can! TIA!

Thanks!

Thanks! That will help with my end result then. And with the exposed perimeter, is it correct that I use the external (exposed) wall (i,e, outside face) rather than the internal (exposed) wall. So in example above the perimeter would be 25metres rather than 22ish metres?

Purely for my own heatloss calcs, so the most accurate method is favoured in this case!☺️

I got my 24 UPVC and wooden doors from E.Europe (German system) for 17.6k inc transport. Better than the utter crap service you get here and they are PassivH. I can dig out the details. In euros too!

I know that it's measured by dividing the exposed perimeter by the floor area, but should the internal area be obtained by measuring all the separate rooms of the house (e.g. work out each room area and then adding them up to get total internal floor area), or should the internal area be measured by ignoring any internal walls?? I have added a pic below for clarity where the internal wall thicknesses would be an exaggerated 2.5m! e.g. house above has an exposed perimeter of 25metres (ignore the neighbours wall). How should the internal area be measured - simply 12x4m or work out each room area first? The former method will ignore the width of any internal walls. So the length of the internal area is 12m or 9.5 multiplied by 4m. 38 vs 48m!! Of course I've exaggerated the widths of the walls, but there could be a big difference in reality if your structure has a lot of internal walls that you either ignore and measure 'through' as in the blue measurement or you measure each individual room. I've seen people do it both ways, but they can give very different ratios (0.68 vs 0.54 in this example). Many of the insulation sites are very vague on this also.

I'll phone a local EPC assessor today to see what they say. https://renewable-heat-calculator.service.gov.uk - playing around with that, the heat demand also appears to be determined by what the heat source is. Coal gives a higher figure than electric gas or oil. So maybe I should state that I am getting some grotty coal furnace to do the space heating and get a higher KWh rating!! Yes, the guidelines state that you need to have loft/CWI if that is a recommendation ("If loft and/or cavity wall insulation is recommended in your EPC, you must install it and then get a new EPC. Your new EPC must reflect your newly insulated home": https://www.ofgem.gov.uk/system/files/docs/2017/10/essentialguideforapplicants_rpiia_4.1_october_2017.pdf) so I may as well sort out the loft roll before any assessment takes place and get some evidence that I will have EWI at some point (or forget to mention to the assessor that most of the CWI was taken out!).

Still considering my heating options (see here) and looking at the RHI on an ASHP, I see that I need to get a new EPC as the other one I have is more than 2yrs old and the rating at the end of the highly useful report? tells me it an ' E' (46). So I would need to get a new assessment done before I have the ASHP fitted (should I indeed go that route). If I do decide to go down the ASHP route, then I want to get that installed at the same time as all the rest of the plumbing systems and not have the mess/extra labour visits/costs to fit an ASHP after the house is 'complete'. As of today, I have a shell of a house still. Would they still be able to undertake an assessment? Windows and doors in, so that'll be a tick for the 'doubled glazed' box on the assessor's sheet and I get a gold star for the panels on the roof. But I have no heating, the loft is bare (no insulation), old crappy CWI is mostly gone, so my efficiency rating would probably be closer to an F than an D! In terms of the RHI, that appears to be based on the total heat demand - but how is that assessed if I have no heating installed yet? Do I just inform the assessor that I will be fitting UVC/ST/Sunamp/re-instating the old oil boiler?

Well I wish I knew what I was doing also - believe me! Been pondering all day about this. 350L UVC with an additional buffer is probably going to cost at least £1500. But bigger losses obviously heat-wise. Space heating and DHW requirements (paste job from earlier): DHW requirement: 2 adults and two soon to be teenagers (so they will hardly wash reducing the DHW figures a bit) 2 morning showers 2 evening baths Hot water for washing up (though may get a boiler-type tap for most hot water needs in the kitchen) Occupancy: Wife and kids out and I although I work from home, my office will be one of the sheds out the back so main house can either be set to off or very low temps during the day. UFH demands: Groundfloor: Water volume: 129L; Estimated loading: 9.45Kw Upstairs: Water volume: 25L; Estimated loading: 2.03Kw The price reduction in the SA has confused my thinking even more, especially all of their variants now of UniQ range. I think that may confuse others also especially since their site is woeful with explaining their new generation/range of options. But I hear they will be sorting that out soon. I have a feeling they are a bit under-resourced/overwhelmed with enquiries. Until I hear back from them, I will post qs here. Someone kindly sent me some info on their latest UniQ rangeUFH and With a 12KWh system, that appears to cater for 2baths 2showers. So if the SA is fully charged that should be sufficient heat for 2baths 2showers, right? During summer months when my solar PV is producing 15Kw, that should replenish the sunamp for the evening baths and showers, correct? Any surplus PV goes to the grid (I'm only on 4.85p export tariff so worth putting everything into sunamps). Winter is different of course and I didn't collect any stats from my PV setup yet to see what I generate, but assuming I make 2.5KWh, I would rely on the gas boiler to supply the majority of the heat energy for the 12KWh SA unit - best to have the boiler feed the sunamp in one hit at it's optimal condensing settings? 2baths 2showers/day would be the max for 95% of the time. Taking into account the UFH demand of a further 12Kw that would be met by the gas boiler also, but at least the heat loss from the Sunamp unit is minimal. But can the UniQ range be rigged up direct with the boiler or does that still need a buffer tank? And with the boiler in the mix here, do I need a UniQ Heat unit or can I plug the boiler into the UniQ ePV unit also? So @Nickfromwales, as the wife wants gas for her cooking I am thinking of using a gas boiler with SA unit(s) and do away with UVC/TS completely (Saving £1500ish). Ideally get rid of the gas too, but she's made up her mind...and being Welsh, that's it! Sunamp UniQ ePV 12KWh will be double in cost at £3100ish, but probably a false economy in my sitaution to wait for prices to fall as I have no heat source at all now (no point installing UVC now only to rip it out in 2yrs time when SAs will be cheaper again!). My understanding of how these sunamp units work are probably a bit off the mark still, but hoping they give me call back soon.

No, not mine that. Mine got deleted from youtube.

Thanks for the headsup on pricing coming down. Was not sure what SA unit Nick was referring to costwise earlier: So I was looking to get two Sunamp PV units @9kw each as the plumber mentioned above,which with I guessed would cost 4 x £1700 (per 5Kw PV unit - I found that price online somewhere, probably dated) to give me a figure of £7k. So if they have come down to £1k then that will really push my decision towards SA rather than UVC. Yes, been there and considered that also. I have gas (boiler not bought yet) but liked Nick's pros and cons that were mentioned earlier. Not looking for ASHP in this setup.