TerryE

Just don't forget to check if you do have a long cold snap as letting this freeze and backup will be a total PITA.

This a good idea if you want to guarantee that it doesn't freeze. if you lag down to G/L and use a small soak-away as @Kelvin and I suggest then you probably would only need to turn it on for the few days over winter when there is a sustained hard frost. We don't have this prob since we vent ours internally into the foulwater stack system using a McAlpine In-Line Vertical NRV (these are designed to allow these and similar overflows to be fed back into the FW system). The nearest we have is that we feed all of our potable water through a Harvey water softener. This is great for cooking and brewed drinks, but we prefer taste of the unsoftened mains for drinking as plain or fizzed water. I have a garden tap by the back door that taps directly off the riser before the Harvey, so once every day or so I take a big jug outside to refill all of our glass water bottles that we keep in the fridge from the outside tap. This is a tiny hassle and far less than that of adding an extra unsoftened water tap inside. This outside tap is similarly lagged and does freeze up a few days a year on average. When this happens, I just take a kettle outside and defrost it if our need to refill is getting desperate. Not really workable option for an overflow.

These sorts of trickle overflow are often turned down into a small stone chip or fine gravel soak-away at ground level, maybe the size of a plant-pot or bucket. The pipe should be insulated to ground-level. I am not sure where you live in the UK, but the ground very rarely freeze much more than the top few cm where I live in Northants even in the worst cold snaps, so this approach takes the water away without leaving puddling with can freeze and cause a slip hazard.

This outlet design will cause probs, IMO. The horizontal run will cause standing water which will start to freeze from the drip, building up and then block. Perhaps a case of aesthetics over fitness. 🫢

Janet simply hated them for their flaws, but I was torn: I really liked the concept but there are so many design issues left unaddressed or unoptimised that I am glad that we decided to replace ours. Take the issue of the strict cuboid form factor. Superficially this has lots of installation advantages because you can install the unit in a tight space without much space overhead -- except this is a dangerous assumption unless all of the risks are addressed. For this concept to work you would really need a unit designed for all maintenance access on one side, and this is not the case. All components that don't have a life that is significantly greater than that of the overall unit could fail in life and therefore need to be field-replaceable, e.g. heat sensors, heating elements, etc. The fluid design issues can't be ignored but IMO they largely are. The Sodium acetate trihydrate (SAT) PCM is heavy (S.G ~ 1.45) and cycles through a phase change roughly daily. The PC expansion coefficient is small but not zero, so the unit must be designed to facilitate this flex, and ditto all connectors and fitted components. A strict cube is a bad choice there. The cylinder is preferred for a reason. The fascinating Youtube History of the Jerrican discusses the evolution / design of a similar cuboid container that has been largely unchanged in 70 years. The SAs use plastic cells in a bolted steel box for support, but if you remove a side panel for maintenance access (except when the unit is completely cold) then game over. Ditto heat transfer. The unit needs to support ~30kW thermal transfer from the PCM to the potable water and this requires internal cell design especially as this has to happen throughout the phase change cycle. The SAs do better here, but IMO the UniQ implementation is still far from optimum. I could go on with more detail, but this post has already lost most readers so time to pause.

As you may have gathered from this thread, SunAmp units are far from maintenance free, and so IMO they need decent maintenance access all round, compression turn valves on all in/outs and the ability to slide the unit out in extremis. We made the mistake of not doing this. They are also extremely heavy. So my suggestion is that if you do want to "hide" the unit in a "wardrobe" then install it on a platform and make your "wardrobe" open backed and fixed to the wall with bolt fittings so you can unbolt and temporarily remove the wardrobe entirely for easy maintenance access when needed.

If you can't get a decent consistent finish then you might need to paper the ceiling with lining paper to get a decent uniform base for painting.

What happened to your idea of anti-PCM bund?

Chip off a bit and try to dissolve it. It hardly dissolves in cold water but you can get it to dissolve in boiling. TBH, I suspect that even with mechanical removal / steam cleaner, it'll be hard to get back to a decent decoration surface. From the OP, it looks like you've got the edges of 4 or 5 8×4 PB sheets compromised that wont take decoration, so there is quite a lot to take down / replace. One alternative to stripping out the entire ceiling might be to sand down then put up a second PB layer on top.. @Nickfromwales, if this is isn't giving recurring nightmares, you might have some remediation suggestions.

@MikeSharp01, this is an artefact of SAP rather than a real issue. Last night we used 2.3 kWh heating our after back to target. We've got a bit of a Dunkelflaute at the moment so the cheapest was 18.2p so or H/W cost about 42p. SAP needs fixed not the implementation.

I assumed that the PCM salt would be soluble in water. I found this not to be the case once the salt had changed into the solid crystal phase.

Glad to have been a help. As I mentioned out kitchen is essentially arranged in a U around a 2×2m walking area with a peninsula walnut work-surface acting as a divider between this and the dining table / area. We have full-length storage on one wall of the dining area for low-access items and storage. Hence 95% of our kitchen work is only a step or two away from the sink or induction hob. When I need to access the full-length storage, I do notice the extra 10+ paces that I have to take to get there and back. It's easy to make up a temporary table / island from a couple of cheap internal doors and DIY trestles made from 22×44 PSE timber, all for under £200 I made some up for Jan over 10 years ago. I used them for an ad-hoc working surface during our build and still get them out or our storage room, and put them up a few times a year to do jobs on. In terms of your pics, my Q to you is: do you see yourself spending your time? Cooking in important but I doubt that few spend more than 10 hours a week doing so. Also what you need to do here is to focus on how to make this time efficient and least tiring, so positioning and placement is a key design driver. If you are going to spend more quality time relaxing in the sitting area then surely you should constrain your options here and focus on the correct balance between relaxing and preparing food.

@Jeremy Harris, really nice to hear from you again. Please keep in contact. You've been missed. You seemed to pretty much to have removed your Internet footprint, especially with the lapsing of the mayfly domain. I once did have a search and I found an email contact some in some other context, but decided not use it in the end, since I figured that this would be intruding on your privacy. Anyway back to SunAmps. As Mike said, in the end I gave up on them, and have posted on this journey on several topics. In terms of replacement, I went for a decent OSO 250L UVC (immersion only). This has a cylindrical vacuum panel jacket similar to that used in the SumAmps. The daily parasitic heal loss is somewhere between 1-1½ kWh; this only about 30% more than my 2 SunAmp PVs. Not enough to cause overheating, and this does ultimately heat the house at a CoP of 1 anyway. I have top and bottom digital thermos and once a day my control system uses their readings to estimate the top-up heat required to bring the UVC back up to temperature. I then schedule heating for least-cost on my Octopus Agile tariff so most days the cost of H/W is around 20-50 p, and often less. This all works well, and we've never regretted the switch. Now lessons from the tear-down of the defunct SunAmps: 10/10 for the concept; 2/10 for controller board design and implementation; 5/10 for the mechanical implementation, but overall I don't think they were engineered for a 10 =-year life let alone something longer. The form factor also encourages supplier lock-in. They were still using the same controller board until recently for the UNIQ series. They were really terribly electrically, thermally, etc. Just nowhere near what I'd expect on a product at this price. I was replacing one every 2-3 years. I can go into more details if you want. I had one of the thermometers fail as well In terms of plumbing construction, the PVs were a nightmare, in that they were practically unmaintainable in-situ. When I did the tear-down, just too many joints were weeping and showing bad corrosion. Clearly there was steady dripping into the internals in one unit. This might have been addressed in the Uniq units. However note that @Nickfromwales and others that reported issues with the internal cell immersion heaters for the electrical boost option: these aren't a replaceable component. The only practical option is a complete cell swap and this isn't a field-repair option either. One of the 4 PC cells showed evidence of internal corrosion on the internal copper at a solder joint. If this went then this would have let the potable water bleed into the salt chamber and ultimately caused the sort of failure that you experienced. So IMO, if you do do a SunAmp swap then you should anticipate a similar life of under 10 years for the replacement unit.

TBH the internals should be dry and well drained, so personally I'd just do it in timber, e.g a length to wood decking or other preserved wood from Wickes or equiv. You cam pick up a length of 25×120 mm decking for about £8 and cut to form a U profile cover with a nice sloping lid. Easy to fix to the wall. Maybe not the most beautiful, but it will do the job and stop your drain blocking. And yes, in 10 years time you might need to replace it. 😅

Once insulation gets (even slightly) wet then the U-value collapses. I would route the pipe vertically, and box it in with a mineral packing in between the pipe and the boxing.