paulmb

Hi, are you give any update on how your choice of larch cladding treatment has faired since application in 2017? I'm about to get a small 1BR unit built on Skye in an exposed hill-top location by the coast, so have similar concerns to yourself on how it will weather over time.

While coming late to this discussion I am facing a similar problem to the original poster. One architect suggested a similar warm battening approach but over a tanking membrane fixed mechanically to the wall. The tanking membrane has dimples that hold the membrane off the wall about 7mm and by proving vents in the wall any moisture in the wall is supposed to be able to escape. ive been searching for confirmation of this approach but had little success. The membrane supplier reported having used it on a barn conversion in combination with rock wall between the battens rather than a rigid insulation under the battens. Im leaning towards metal battens fixed to the wall and insulated plasterboard over. The alloy battens won’t rot and provide a 30 gap for air flow over the wall which with vents top and bottom should allow and rising and ingress moisture to escape.

I agree that EWI could result in the best solution if one is willing to make changes to the roof so that it overhangs the top of the EWI. I appreciate there are alternatives but don’t feel confident in them. Also there aren’t EWI specialists locally so bringing them from afar adds to cost and project management complications. Another contraindication against EWI is the lack of a DPC. The thinking being that moisture rising in the wall needs to escape somewhere and that a ventilated internal cavity will provide that

I have a very similar challenge to several if the posters above, to covert a small 1930’s church with solid brick walls to a residential dwelling. Located on the Isle of Skye externally rendered with a cement based wet dash (ie non permeable - except when cracked and blown!). Like the OP I’ve read widely and found much sometimes contradictory opinions from ‘experts’. One approach suggested by a local architect that isn’t so widely discussed is to use a tanking membrane fixed mechanically to the wall an fix rigid insulation over it, with battens over (warm battened). Ventilation and/or drainage is needed behind the membrane which is sat off the wall by the dimples in a the membrane, creating a slim (7-8mm) gap. The insulation is butt jointed and taped and cold bridging is minimised. That’s the claim. I spoke to one joiner who had used this approach locally without the battens and sounded like it was tricky as he said he’d only do it again with battens. Has anyone else had experience of this approach? I spoke about it to the tanking membrane supplier who indicated that they would suggest now using rigid insulation but a Rockwool instead to help the the cavity breath, but think that suggestion was to place the batts between battens fixed directly to the membrane (cold battened) still wrestling with with which way to go - but am leaning towards metal battens fixed direct to the wall and insulated plasterboard over, with vents top and bottom to allow moisture from below and the wall to escape.

While I can understand why it might be desirable to defer re-charging until cheap or free electricity is available, I don't understand why it is necessary from a PCM technical perspective. I mean, is it always safe (from an over-cooking the PCM perspective) to power-off and on again to potentially trigger a re-charge when there's no spare capacity? i.e. if the Uniq battery was fully charged, and then power-cycled as @JSHarris is doing daily to trigger re-charging, is there any danger of over-cooking it?

I'm not sure that the above is completely the case - as just last week I innocently entered an enquiry on the SA web site which was responded to with a call from a SA business development manager, followed by an email containing version 2.3 of the Uniq Heat Batteries reference manual, and a couple of followup email exchanges. It's gone a little quiet since I referenced the dialogue's on this forum to them...

In the discussion of using ASHP's with SA products, can someone clarify where the 'rHW' and 'rHeat' configurations fit? I'm referring to the SA products: UniQ rHW Heat battery for domestic hot water only, which is heated by an external heat pump using the heat pump refrigerant circuit i.e. the refrigerant flows through the heat exchanger in the UniQ rHW store. (OEM only) UniQ rHeat Heat battery for space heating only, which is heated by an external heat pump using the heat pump refrigerant circuit i.e. the refrigerant flows through the heat exchanger in the UniQ rHeat store. (OEM only) I'm not familiar in detail with ASHP's, but was told yesterday that there are some that require a 'refrigeration engineer' to install and service, and some that don't - so do the above SA models require a refrigeration engineer and hence why they're only available to OEM channels? If that's the case, then is all other discussion of ASHP's here referring to ones that produce hot water as output?

From what 'we' know, does the 50/90% charge threshold issue apply to all configurations that are heated from the internal electric heater?

Ah, @JSHarris, I'd mistakenly assumed you were using one of the PV specific configurations ePV or dPV The terminology is quite confusing, but I'm starting to get the hang of it I think. Any SA with the term 'Dual' in it refers to providing 'dual' space of hot water heating right? And as there are only 2 water circuits (high and low power), then all 'Dual' SA's are powered by electricity, which either comes from a PV specific supply (from which it will accept charge at any time), or from the 'grid' (i.e. local home power circuit which may or may not be being supplemented from PV). That being the case, (notwithstanding the fact that @JSHarris has apparently a controller with a PV suffix which is still confusing me), the 50/90% threshold is a little more understandable, as I assume the intention is to drain the charge down and re-charge it overnight from E7 power, though clearly that's problematic if you've got a system capacity that doesn't use > 50% during a day...? Does the control unit of the 'e' systems have the option of when to charge, or is it all charge-threshold based? For my potential use-case, I was hoping that an eDual system would be able to supply space-heating via UFH, on the low-power circuit and DHW on the high power circuit, enough for 2 adult occupants of modest 1BR well insulated holiday unit which has low space heating requirements. However if it does seem problematic if guests showered in the morning, but it failed to use enough DHW to trigger a charge, and return in the evening and want to 2 further hot showers but run out of hot water... That can't be right - I mean how are these units intended to be used, regardless of maximising their PV usage...?

Thanks @JSHarris regarding the 20m PV->SA cable. I need to further show my technical ignorance here, but I haven't quite understood the reason for the PV specific SA configurations. I mean PV generates electricity that can be consumed directly by appliances in the house or exported to the grid right? So why can't one simply use the SA heat stores that are heated using an electric element that is plugged into the house's electricity circuits which may or may not be being supplemented by locally generated electricity?

Having waded through the many pages of this thread, and a related one that started on the problem of the bulging case, I was really hoping the saga would have a happy ending in the form of a SA provided solution - alas that doesn't yet appear to be the case. So as I am looking at possibly 3 different SA use-cases for off-mains gas locations on the Isle of Skye I've tried to engage with SA about the suitability of their products, including referencing the concerns raised in this thread, and got the following, somewhat confusing response: If I do receive any clarification, I'll be sure to add it here, but in the mean-time I have a question you guys might be able to help me with. When using the PV->SA Uniq heat store configuration, what is the maximum reasonable distance between the PV panels and the SA heat-store? The reason I ask is because we already have PV panels on the house, but one of the possible SA use-cases is for a small 1BR holiday unit being built at the bottom of the garden, probably 15 - 20 meters from the panels. Would it be possible to direct the PV generated power from the panels on the house to the SA Uniq unit in the new holiday unit?