TerryE

thanks everyone

We've had our twin cylinder Harvey 2 water softener in commission for coming up to 2 years and I haven't done much apart from change the salt blocks as required, yet I've noticed that there is now a definite asymmetry: the left block seems to get consumed at roughly 1½× the rate of the right one and I am getting salt crusting on the sides of the salt-block slots. I just feel that it could do with being taken outside and my giving the whole thing a good hose down and make sure that no small orifices are blocked. I was just wondering if any other members with these do any form of annual maintenance. @JSHarris, @jack, etc.?

And the RPi 4 is now out: thePiHut -- Raspberry Pi 4 Model B. USB3 so SSDs are about 7x faster and now supports TRIM protocol. The Gb Enet is now proper 1Gb throughput. The CPUs are maybe 50-100% faster and you have 1,2, and 4Gb RAM options.

Not true, IIRC in out case the wall losses were only about 30% of our total heat loss so this would on its own represent perhaps a 5% increase in your heating bill forever. However as Mike says, it is really worth playing with the numbers using a simple spreadsheet approximation such as Jeremy's. Your heat losses are primarily mix of wall, floor, roof, fenestration and air leakage circulation losses and you need to get a good balance. So for example, IMO, if you had to chose between 0.17 + no MVHR and 0.2 + MVHR, then the second option is by far the best. I went through all of these trade-offs when I was trying to decide whether to have a single-wall or twin-wall TF. In the end we went with MBCs twinwall Larson-struct construction. In retrospect, I have absolutely no regrets -- not for the slight U-value improvement, but for other factors that I didn't even consider in my design trade-offs: The cellulosic-filled twinwall has a far higher thermal capacity and decrement delay which makes the whole environment a lot more thermally stable and pretty much insensitive to external diurnal temperature variation. The blown-fill open panel cavity is intrinsically more airtight than pretty much any of the construction alternatives. You are also far less vulnerable to quality issues with insulation fit and potential airgaps / cold spots. So at the end of the day this is all about trade-offs. A good exercise is do the first design iteration then give yourself a £5K improvement budget and look in turn at using this to improve any one of the above components. If one stands out then you've got the balance wrong.

Andrew, why the floor void? This really complicates this type of floor. Quite a few of us use MBC raft designs. Their SE demands a geo survey and the approach that he adopts in perhaps 90% of cases is to build the raft on a sub-base made up of 50 mm layers of course crushed gravel. The depth varies account to soil conditions, but we had 450mm for ours on Gault clay, IIRC. We used MOT 1 for the top 50mm to blind it and this was then topped by a 50mm sharp and leveling layer and the slab poured into structural grade EPS which both acted as the former for the slab and the insulation. No void at all. We had a land drain around the perimeter of the sub-base emptying into a sump that we could pump out before the proper drainage was in place. Having a void below ground level is a bad idea IMO. It's not a good idea to have a lake below your living area. And either way foamGlass should easily support your frame. Get your SE to do calcs. It solved a bridging issue that we had and our SE signed it off.

I am another self-builder with an electric only passive-class non-certified house. A couple of things to consider: Your loft space: if you are considering making this living space then at a minimum do all of the structural and at least 1st fit work during initial construction. Also make sure that you have any roof lights, etc. in the initial build so that commissioning it doesn't change the external look of the house and therefore fall foul of further planning approval. Our estate agent for our old house had a look at our new plans and he was the one that suggested that we include our loft space as living space from day 1 -- far cheaper to do than doing a conversion later on. A decision that we have never regretted. We haven't got a thermal store. We use a SunAmp system (lots of discussion on the pros and cons here on the forum), but the big pluses are that it this is thermal energy dense and also has incredibly low heat losses, so our entire 'plant room' is a cupboard off our ground floor toilet. We use our ground floor slab as our thermal store for space heating. Do the math: that amount of concrete has more than an order more specific heat capacity than any conventional TS. Again we've had various threads on this. ASHP vs GSHP. Again research all of the threads on this. I realise that you might be tempted to go the GSHP route given your acreage, but the consensus here seems to be that ASHP is better in terms of through-life costing.

To which Jan replied "F*** knows; I can't remember." Unfortunately we are in Alonnisos and the paperwork and invoices are in a folder in the UK. As others have said, the problem is that the whole job involves a lot of itty-bitty trades and site visits. Better to split the work by trades IMO, and do the ones you are doing yourself, and the others to your preferred tradesman. The tanking bit is pretty straight forward but time consuming and something either of you should be able to tackle.

We've got 3 wetrooms in our house. Jan did the tanking using a standard kit. I did all of the chippying and we did the plumbing. The only bought-in labour was for the tiler and IIRC he charged less to do the entire ground floor, the 3 ensuites, bathroom and ground floor toilet. I'll ask Jan in the morning.

As the guys say one or two Willis heaters will cost under a £100. We've got a decent spec 4 double bedroom house, and we keep it toasty over winter with one Willis heater, and as F say the advantage is that having this makes your ASHP non-critical in terms of maintenance: if it goes offline even for a month in the winter the incremental cost is in the £10s.

See our Dew Point thread and specifically

As @Simplysimon says you need them around any fenestration opening which breaches the airgap. And on corners and I would also suggest at the eaves. There is not need to barriers between floors s in an English 2 two-storey single occupancy dwelling, but they are required n Scotland, IIRC. The aim of the barriers is limited to providing 30 min protection to allow the house to be safely evaluated. If its any form of multi-occupancy then the requirements have a step change. Barriers in any penetrations to the internal plasterboard skin is also needed: intumescent pads in the back of all power sockets etc, and a red sausage stop at the top of each service void and any through floor penetrations. What you don't want happening is a hidden fire within the service void working its way into the floor voids and across flaws.

We didn't and didn't have any problems. The MBC crew that we used said that they'd never had any problems with any of their slabs. We use an up-and-over pumping system for pour so we didn't have any material issues with heavy barrows over the pipe runs. So IMO, the risks are low and if at all they are during the pour itself. There are two other factors that you need to consider: We were getting our slab laid in early Nov, so there was a real risk of the slab going below 0°C with water in the pipework. Really not a good idea, so you should really blow out the water after the test. Doing the pressure test involves fitting the manifold (and possibly needing to reposition and refit it when you have the TF adjacent wall in place), as well as the test itself. This is going to man that the MBC crew is going to have to schedule a gap day between completing the UFH (typically the last thing that they do before the pour) and doing the pour itself. I did do a pressure test (IIRC, about 6 months later in the early spring) and cranked the loops up to 5 bar with no problems. We run the UFH at 1bar now.

Fair point Ed. But we operate our three loops as a single zone so we don't have TRVs on the manifold. The other advantage is that all this stuff in is a single services cupboard with a concrete floor, so no risk to carpets.

@jonM, in our last house, we had one rad that spontaneously developed a pinhole leak over a weekend when we were away and came home to find the landing carpet and living room carpet below sodden. We also had 3 TRVs need replacing whilst we were in the house. My son has just spent £300 getting a leak fixed in his CH system in his 10mm copper piping in the ground floor concrete. So that's two instances where I can personally testify of major failure in conventional CH systems. On the other hand the PexAlPex UFH are continuous in slab (no joints because I watched them lay it). I am confident that jointless PexAlPex UFH will out live me.

UFH every time. Like many others we have an MBC twin-wall with a blown cellulosic insulation filler. We also have an exterior stone stone to fit in with the local context. UFH on the ground floor heated by an inline 3kW (Willis) heater. No heating on the 1st or 2nd floor apart from an electrical rad in the master bedroom en-suite. No rads anywhere. Cheap, simple effective. I have to offer a dissenting opinion to @jonM's designer. I feel that he really misses the main point here: if you have a reasonable specification passive design (our slab, TF + insulation and air-tightness cost less than our stone skin so it was hardly an expensive option), then you just keep the whole house at the same temperature all day and year round. It's just not worth trying to save the odd £100 p.a. by trying to have different zones or shaping the heat across the day. A couple of times we've dropped our heating for a day or two. We didn't notice because the house only loses about 1°C / day in temperature with no heating; and it then takes a couple of days to regain this, and if you try to force it you end up in an over-compensating roller coaster. Our 1st floor might be a degree or so cooler than the ground floor in winter, but we prefer that. I don't know how we could get it much cooler if we tried. As with Jeremy and others, the supplier's site team tied the UFH pipework to the rebar grid in the slab before the pour: a ½ day's work instead of all those rads and internal plumbing. No comparison, IMO. The difference is that there is no maintenance needed for the pipework in the slab for the life of slab, but rads and TRVs etc. will need maintenance. Also not having those bloody rads under the windows everywhere just makes decorating and dressing all the rooms so much more straightforward.

@JamesHopeful, read your NoD carefully. We have this one as well and AFAIK, this clause is pretty standard. Minor interior changes such as moving an internal doorway or adding internal non-load bearing walls are one thing, but the planning enforcement may take a very different attitude to changes which impact the exterior of the property such as the look of the principle elevation, changes to overlooking, or even the distance of the property from any neighbours.

I use E7 low rate to heat my 2×SunAmp PVs, and to be honest we seem to use so little hot water that there isn't really the cost justification of adding a buffer tank for preheat even when we install our ASHP. So the big pluses for this approach are (1) simplicity; (2) No Part G3 requirements so I could do everything myself. (3) still relatively low running costs for our usecase.

Gives the tide mark too long to settle The boss likes a spotless bath.

Sad isn't it? Though I tend to compromise and let it cool to around the high 20s since this is moderately quick and losing that last 7°C or so takes quite a long time. What a bunch of sad old farts. I must admit that you can get a bit too anal about this. Bare with this seeming non-sequitur: Jan and I have a massage every two weeks turn and turn about (and before Clive starts chipping in with his dirty innuendos, this is a straight Swedish-style massage and no funny stuff). Even before we add our ASHP, our monthly energy bill is almost exactly the same as our massage bill, and under half our council tax.

I am very happy with my 2 × SunAmp PV, but reading this thread, then if I was having to start again with SunAmps, then I'd be tempted to stick with the UniQ 9 HW using a external Willis and circulating pump to heat it. That way I could have precise control of the heating strategy.

Consider using a twinwall Larson strut TF with blown cellulosic filler. Better decrement delays.

TBH the only thing so far (after 16 months of occupancy) was that the TF construction crew put in cross bracing 50×75s (IIRC, but the might have been 50×100s) threaded through the ecoJoists during erection and these were nailed to the ecoJoists at the intersections. On one cross-over in each of the main and guest bedrooms there is maybe a couple of mm flex which causes noticeable creak as you walk over them -- trivial to fix before boarding out, but we would need to lift carpets and do keyhole surgery to fix these now. Even so, given that two floor creaks are my only annoyance, I think that I must have been lucky / all that anal attention to detail has paid off.

As I say, it all depends on the local context. If you can keep them onside, then this is best option. Some LPAs seem to encourage the arsehole approach

The planning Enforcement Officer (EO) might pick this up, depending on the local context. Their enforcement action could in the worst instance be to require you to strip off all the weatherboard and replace in wood. On the other hand if you submit a NMA + provide samples to agree the change, then you also risk getting this turned down and having pre-warned the EO about this issue. It really depends on the local context and your relationship with the local planners.

We used JHAI. They seem to do 3 visits as standard during the build: foundation; outer skin ½ up for internal frame and validate airgaps, etc.; and final inspection. We also had our BIsnp come around once pre build at the design stage, and he made some very useful suggestions / recommendations. For example: We had to change the internal build design and re-layout our 1st floor landing and 2 flight to loft floor, because of marginal headrooms -- something that was easy to change before we had finalised the timber frame design with MBC, but which have involved major rework if only picked up during inspection. We also had foul-water gradient issues because our stacks are at the rear of the property and the sewer access to the road at the front, so we discussed options and he agreed to having a foul-water run straight across and under the slab centre -- so long as we had rear rodding access. I also resolved a couple of other issues by email. I was somewhat amused by the final inspection, as it turned out. I had gotten a bit paranoid about issues that might come up, so I had made absolutely sure that we had nothing outstanding and I had gone around dotting i's etc. so to speak, but when the inspector came his opening observation was: "Just by looking at the frontage, I can see that you've obviously done everything to top spec, so I doubt that I'll find any issues", and he basically breezed around the build cooing. Even so, our lead Inspector did decide that he wanted copies of three other certification documents before issuing final sign-off -- one of which he already had, and for the other two he accepted copies of my previous self sign-off commissioning reports (MVHR and DHW / CH); another upside using of SunAmps -- no safety issues requiring independent 'competent person' sign-off. We JHAI also acted as the inspectors for our warranty provider and so these inspection doubled up for this, though we did have an additional site visit by the WPs technical manager. Overall, I was extremely pleased with their service and would recommend them on this basis.