Cooeyswell

Sorry folks that number was pulled from memory - and was clearly wildly incorrect. The average window U-value is 0.9 (Rational Auraplus, Triple glazed, magic coatings etc.) The house is South facing, Coastal and Northern. Overheating has not been an issue while we have lived here. Salt deposits on the windows provide all the shading we need 🙂 Not sure how PHPP handles this.

I have weeds and grubby paving - let me know how this works out

Passive spec- 0.1U-0.12uU in all directions, 0.15U windows, MVHR etc. The usual stuff. I lived outside Chepstow for many years. At no point did I encounter Welsh cooling undercrackers, neither has anyone here suggested the application of Welsh crackers (under or over) as a cooling mechanism. I look forward to being enlightened.

As quoted by our representative from the sunny uplands of southern Wales. I'm living in a Passive spec build in a northern land - cooling ain't an issue.

I'm in much the same situation regarding scrappage. The jerrycans are currently sat under a workbench in the garage but I can't see me using them again so they need to go. I guess the practical thing to do is to cut them up and separate the waste for recycling. Sunamp confirmed the use of food grade Sodium Acetate Trihydrate and its recyclability a couple of years ago (also its use in salt and vinegar crisps) so no issues there. I would consider whether you can make use of the vacuum insulation panels before you discard them. They are relatively expensive and hard to come by. I have reused the steel case and the vacuum insulation panels to insulate my new LFP battery system. The rest is mainly e-waste and can be recycled.

A quick follow up on this. After 5 days of operation I have used 5 units of peak electricity, all other usage has been successfully covered by the battery. I do see import from the grid when running high power items like the 3kW kettle, but this is relatively small in the scheme of things (~700W for 2 minutes). I also see import when an appliance exhibits "burst" behaviour - in my case both the induction hob and ovens - This appears to be due to the speed of response of the inverter as it ramps up to cover the demand over a few seconds. I assume I may be briefly exporting as the inverter ramps down as the load cuts off. In my case the 3kW inverter is looking like the right choice.

I did look at 5kW inverters, most of these seem to be hybrids and cost around £500 more. Bizarrely several 5kW hybrids will only provide/source 3k to the battery (Growatt). They also (as mentioned) require a G99 sign-off prior to the install along with payment. G98 is a lot simpler. I think this size gives the best "bang per buck" for my purposes. I am not attempting to cover all power consumption scenarios. From observation I expect to cover 80-90% of my peak usage with a 3kW system.

I am in the process of self-installing just such a system. In my case the hardware is A Seplos Mason 280L (14.4 kWh, A-grade cells) £2156 A Solis RAI-3.0KW 48ES 5G AC Coupled Inverter £640 I don't have or plan to install PV. I will be using this system to shift the majority of my power usage onto E7. Just finished the wiring today, tomorrow is the big switch on Wish me luck

That's an interesting option - I don't think I have come across one of these before

I have exactly the same democratic discussions and house voting system. After 40 years my better half is used to my tech inspired diversions but is equally well versed in analysing them. So after two periods of extended cold showers this year I got the following questions :- - Are you happy to be having cold showers ? - Do you think I'm happy with cold showers ? - Do you think your 91 year old mother was expecting to have cold showers when she moved in with us ? - If we don't replace it now then when ? ( Please show your working with a detailed schedule) - Who the **** is going to fix this **** after your demise ? (that was after day 3 of cold showers, the "imminent" was implied) - If you die "unexpectedly" due to a freak cold shower incident, who do I call ? (Number for plumber not undertaker required). I took the hint.

The full horror is exposed in https://eur-lex.europa.eu/legal-content/EN/TXT/HTML/?uri=CELEX:32013R0812#d1e32-123-1 In particular Annex VIII - Section 4. It is calculated from a load profile given in Annex VI and may have no relationship whatsoever to your usage.

Exactly the argument I used when I originally bought the Sunamp PV. However your calculation of cost doesn't factor in the additional cost of purchase (£2K Sunamp Vs £1k OSO) or the replacement cost when the element fails just after the 10 year warranty period expires - the OSO has a 25 year tank warranty with easily replaceable immersions. The unwanted has warming is largely irrelevant in our large-ish passive house given its exposed, northerly location. Given that the OSO is cool to the touch when fully heated I don't see it being an issue for me.

It worked very well for 5/6 years with no problem. Then it started to get issues. My guess is that Sunamp realised that the Sunamp PV was overly complex relying as it does on multiple sensors, a modulated water pump and a control board with relays etc. Such a system may have been viable if sufficient debug information had been made available but it wasn't - at least not to the end user. My understanding is that the current systems have been simplified but that an immersion failure requires a return to base. So the question is what do you do for hot water while your Sunamp is on a trip to Edinburgh. There may well be a place for a Sunamp in size constrained locations. But if you are just looking for a low thermal leakage solution then a hot water cylinder such as the OSO unit I have just installed may be a better long term solution. It uses vacuum panel insulation just like the Sunamp (so low loss) but has built in redundancy (two immersions) and very low complexity so can be fixed by your local plumber - A feature I feel will be important as I continue to age

My experience with Sunamp can be found here

Just to follow up on my recent posts regarding my Sunamp PV. A few weeks ago it started thermal tripping each night (it is charged on E7 electricity). It was storing sufficient energy for two/three quick showers, nothing more. I had to open the unit and reset it every morning. I called Sunamp and asked for technical support - I was told they would call back, they didn't. I assumed they were busy and waited a week, still no response. I called again got though to the support person I worked with two years ago. Great support (Thanks Ivan), worked through the issue and agreed that the trip was occurring due to a mismatch between the flow measured and the temperature of the flow, The culprits being either the pump, the flow sensor or the temperature sensor. Unfortunately the lack of any debug interface/information on this version of the Sunamp PV means that there is no telling which is at fault. To make things more complex this was my support persons last day, but I was promised a call back from his colleague to pursue a solution. I waited - no contact from Sunamp. The Sunamp-PV stopped charging completely. The pump still appears to be working but the immersion is never energised. The Sunamp is now in the garage, replaced by an OSO direct cylinder very swiftly delivered by Wolseley. So with the benefit of 20/20 hindsight my Sunamp journey is something I should never have embarked upon. - Purchase 2016 for £2K (including expansion unit) - Breakdown in 2021 (Circuit board and thermal trip replaced) - Breakdown in March 2023, (immersion and sensor replaced) - Breakdown December 2023 (Unit is replaced and heads to landfill) To clarify some points. I am extremely techy - this is probably the reason I was drawn to this system in the first place - and was happy to work through the initial breakdowns. However I have my 91 year old mother living with me and lack of hot water is just not acceptable, neither is the lack of reliable technical support on a £2k product less than 10 years old.