Jeremy Harris

We did pretty much exactly what Peter suggests above. In our case we also had around a year's enforced delay (plot boundary problem that had to be resolved) so we used that time to refine the design. I found that my wife found it difficult to visualise spaces from a drawing, so once we'd pinned down what I thought were the core design elements I made a model, at 1/50th scale, using foamboard. If you can draw to scale, then making a foamboard model is surprisingly easy I found. The stuff cuts easily with a sharp Stanley knife and it's about the right thickness for external walls. I ended up making around 6 models before we got the final design as good as we could get it. Very well worth doing, as it meant we got exactly the sort of internal spaces we wanted, with plenty of storage space where we could get at it easily. We didn't use an architect, but that was really because I just couldn't find one at the time who understood what we wanted. We were lucky, in that after a fair few iterations the design sort of came together by itself, so in the end an architect may not have been worth it anyway, but I think that was more by luck than judgement. If you have got a good idea of what you want, and have most of the key features worked out, but just need the design "polishing" and decent drawings put together, then it's worth considering using an architectural technician, rather than an architect, as they are a lot cheaper. My experience was that the only person I found that I could have comfortably worked with was an Architectural Technician, he was a very down-to-earth chap who really understood what we were after. Unfortunately, when we came to need his services he'd retired, so I had to do all the drawings myself.

Thanks, the Enphase ones seem a bit simpler than the SMA ones for what I have in mind; all I really need is the simplest sort of microinverter, I've no need for any of the fancy data transmission stuff.

You need at least 1 1/2 tiles/slates width either side and at least two tiles/slates above (ridge spacing). You can fit the panels right down to the lower edge of the roof with no problem at all, this is what we have done and it makes for a neater look than having a bit of flashing exposed over the lower courses of tiles/slates. Our panels overhang the lower edge by about 50mm, so the run off is clear into the gutters, and we have a layer of that stiff membrane all along the eaves, under the roof membrane, and leading into the gutters to prevent any drips from running back under.

I doubt it's anything to do with storage, as there was a comment from the Ebuild Admin after it closed that the hosting package was already paid up for some time in advance, so there was no cost in keeping Ebuild read-only. I suspect that it's just the way that the restrictions have been set. In the past there were often problems whenever there were changes made to any of the Ebuild settings and I had a feeling that it may well have been a bit of a mess "behind the scenes". I doubt there was any deliberate intent to lock down the images and prevent them being viewed, it's most probably just an unintended consequence of the way the forum has been placed in read-only mode. It's probably detrimental to the Ebuild owner, if anything, in that there is still traffic to the site, so it's still getting advert revenue, but with no images viewable in full size and no attachments accessible, then people may stop bothering to look in there after a time.

On the topic of cardboard, be careful how you try and get rid of it! Like others, we had mountains of cardboard packaging, the kitchen and flooring being the worst culprits. I started off bringing it home and sticking it in our recycling bin, but got a warning note on the bin that it was over-full. I then started filling the back of the car with it and taking it to the local recycling centre every couple of weeks. On the third visit to the recycling centre I was stopped just after driving in and told to leave. Apparently someone had reported me for illegal dumping of "trade waste", despite the fact that I was clearly a retired old bloke driving a Toyota Prius...................... There's another Wiltshire recycling centre a few miles away, so I tried that, and again got stopped at the gate. Apparently they have ANPR systems on their CCTV, specifically to catch banned vehicles from entering. As it happens, our new build is right on the Wiltshire/Dorset boundary and although it was much easier for me to use the Wiltshire recycling centres, as they were more or less in the same direction as home, I found that I wasn't blacklisted from the Dorset one in the other direction, so just went there instead. I probably made a dozen trips to the Dorset centre and they've not yet said a word about me dumping cardboard and polystyrene packaging there. Burning wasn't an option where we are, deep in a valley, as it'd be both a nuisance and a health hazard.

Has anyone any views on the best value/reliability when it comes to microinverters? I'm after just a single microinverter to fit to a single 250W panel that's going to be the lid of the stone box I'm building to house the treatment plant pump and alarm. It's not going to be used for FIT, just as a way to provide a lid for the box that's both weather tight and useful.

If they are 24DC, yes. We have 12V DC LEDs in both our bathrooms, not IP rated, and they've been ticked off as being OK. Ours are set at 2.5m above the floor, IIRC, so well above the limit, and one of them is above the shower.

That's a very good point, as I'll bet that it isn't common knowledge that trusses have significantly higher stresses in the timbers, because they work as a composite frame, with loads distributed throughout the truss. Using joist rules of thumb for making holes in trusses is inherently deeply flawed, but it's easy to see how the lower member of a truss could be considered to be "just a ceiling joist" by some, when it's not at all in terms of the loads it is carrying.

Yes, that's what I've done in our bathrooms. We have higher than normal ceilings, because of the room-in-roof design, so I just made sure all the lights were above the zone height limit, so no need for an IP rating.

That's good news, means there is plenty of reserve in the trusses. I'm still a bit amazed that the electrician didn't consider the implications of drilling holes like this. IIRC, there was a bit back when I did the 15th Ed ticket, 25 odd years ago, that related to the safe areas for cable holes, spacing of them etc. I can't believe that this has changed much since, and it has to be still within the current regs somewhere (I don't have the 17th Ed here on this machine, but will check later).

If the lights fall inside the SELV rules, then my understanding is that they don't need to be IP rated above IP55, and only need that if subject to water jets, if not, then IP44 is OK. The SELV rule is 12V AC or 30V DC, so LEDS running on 24V DC are inside the SELV rule. This is often overlooked or ignored, with there being lots of erroneous statements that "SELV is 12V", but that only applies to AC supplies, such as old-style halogen light transformers.

I fitted all our LEDs in the bathroom above the height limit, to avoid the need for IP-rated fittings. Then again, they are all 12V, so come under the SELV rules anyway.

Our inverter-controlled ASHP pretty much never runs at full power. 90% of the time it's running at its lowest power level, around 400 to 500W input. It also starts so slowly that you can barely hear it ramping up, unlike the noisy full-power start of a non-inverter model. If there is a need for high power, I think ours takes around 30 seconds or so to gradually increase speed, which makes the start far less noticeable. It does much the same when turning off, too, and ramps down gently. This seems to make quite a big subjective difference to the overall noise impact.

Whether a single split would be OK depends on the house layout. In our case we have a very high atrium/hall, right up to the ridge height internally, and right in the centre of the house. It's also probably one of the warmest parts of the house. I'm sure a single small split indoor unit placed very high in that space would be pretty effective, as cool air would flow into both bedrooms (if the doors were left open) and down to the whole of the downstairs. Other layouts might not be as conducive to this approach. The duct heater/cooler will be as least as effective as an MVHR with a built in air to air heat pump, I'm sure. Even the smallest ASHP is around twice the capacity of the Genvex and similar systems. The limit isn't the heat pump, it's really the air flow capacity of the MVHR, which isn't enough, in practice, to have a massive effect. The floor is actively cooled, as described in the blog post. The ASHP is just switched to cooling mode and pumps water around the floor at about 12 to 14 deg C, which seems to be about ideal. The floor surface doesn't drop below about 19 deg C, so never feels uncomfortable, the effect is primarily one of drawing away solar gain from the floor before it can heat it up.

That's similar to the arrangement I'm building at the moment, with a double waterproof socket, and our pump is the same Secoh model. Our alarm is currently a much bigger unit, with a level switch input and a strobe light output, with a sealed lead acid back up battery. The alarm sender unit I'm currently building is smaller than the unit you have, and normally just has a mains power lead plus the small pressure sense pipe, but can have a level switch added very easily. I've just finished testing the outdoor unit hardware and firmware and it seems to be working fine, transmitting pressure and the status of the level switch every ten seconds to the indoor unit. I spent around 2 hours trying to get the pressure sensor working, only to realise that the (Chinese..........) data sheet was mis-labelled, and the connections were a mirror image of those shown. It's working fine now though, and reads from zero to 0.40 bar, which should be more that enough, because the pumps only normally deliver around 0.20 to 0.25 bar when the pipe's blocked. The normal operating pressure should be around 0.12 to 0.15 bar for most tanks, I think.

We have it laid in the bedrooms, so at doors adjacent to bathrooms. A friend laid the same stuff as a bathroom floor, it's water resistant and works well, but he did find that over the course of a couple of years the surface got very slippery, as it became more highly polished from the action of bare feet on it.

These panels run barely warm, certainly not hot. You can comfortably hold your hand on them after they've been on for a fair time. I didn't take any particular precautions, just pushed the rockwool aside slightly, more to make them easier to install than to reduce heat build-up.

The panels I bought came from China with rubbish power supplies, but they are exactly the same panel lights sold at several times the price by some of the UK re-sellers, the only difference being that the UK resellers are generally using better constant current power supplies. Both the 3W and 6W panels need a 300mA constant current supply, with the voltage at the LED unit varying from around 10V for the 3W panels to around 20V for the 6W panels. At the time I fitted our lights I couldn't find a supplier of decent power supplies, so made up my own system for driving the lights, but I would guess that some hunting around would source some decent constant current supplies that don't emit loads of radio interference. There's a bit in my blog about these dreadful power supplies, here:

It's clearly not where the bulk of their target market is, as so very few low energy houses are built when compared to existing houses fitted with PV and combi boilers, so their focus on their core market is understandable. However, it is pretty easy to just install a low temperature "warm water" tank, heated by the ASHP, then use that to feed one or more Sunamp PV units. It doesn't need any complex fittings and the capacity and performance calculations are dead easy, well within the ability of any heating engineer. The only slightly out-of-the-ordinary requirement would be an immersion and time switch set to run an anti-legionella cycle every couple of weeks. A standard UVC, run at an efficient ASHP temperature of, say, 40 deg C, would have pretty low losses, around half the normal standing loss I would think. This could provide the bulk of the hot water requirement, with one or more Sunamp PV units only being used to add an additional 5 to 10 deg to the warm water to bring it to a usable temperature. The Sunamp PV would be, in effect, a boost heater, used only on demand.

I've not measured it, Nick, but IIRC, the Sunamp PV is rated at 35 kW, which is up around the same rating as a pretty good combi, I think (I think our Vaillant can only deliver around 28 kW, again IIRC).

I'd second the view that the panels are great. I have a mix of 3W and 6W round panels in the kitchen/dining room and a rectangular 16W panel in the hall, and they are better by far than the MR16 12V LED downlighters I was using (and still am in the bathrooms, utility room and WC). The nice thing with the panels is that they are barely thicker than the plasterboard and they run pretty cool, so they are easier to fit where the VCL is in fairly close proximity to the back surface of the plasterboard.

Mine is a "straight out of the box" Sunamp PV, with no mods. I just fitted it as per the standard instructions. It works just the same whether there is a combi boiler fitted or not. As long as it's charged up it will deliver hot water at big combi type flow rates.

Yes, pretty much any small split should do the job. There are loads available that are aimed at those with hot conservatories, and they are often cheap and around the right capacity to cool the whole of a well-insulated and sealed house. You can also get multi-splits, one external unit and several internal units, that may still end up being more cost effective that using an MVHR with a relatively low cooling capability. Our Genvex Premium 1L does not provide a massive cooling capability in practice, as, like all MVHR heating/cooling systems it is very limited by the duct airflow rates, so can only really trim the room temperatures a bit, not remove a few kW of heat from solar gain at all. You could make a normal MVHR at least as effective as one with a heat pump in if a cooling/heating exchanger was added to the room air feed main duct. These are water-fed, using chilled or heated water from the ASHP, so are easy to plumb in and control. There's no need to mess around with refrigerant, you just run a flow and return water pipe to the duct heat exchanger. If you fit a duct heat exchanger with a built in condensate tray (like this one: http://www.veab.com/documents/cwk/broschyr/CWK_VEAB_Heat_Tech_GB.pdf ) One of those duct coolers fitted into the main duct from a normal MVHR would provide the same sort of performance as the MVHR units with the built-in heat pumps, but at a lot lower price if you already have an ASHP. FWIW, we find that by far the most effective way of getting rid of excess heat from solar gain is to just cool the floor slightly. I've been cooling our floor to around 19 deg C and that has a massive impact on keeping the house cool, far, far greater than using the Genvex in cooling mode. The reason it's so effective is that it absorbs a fair bit of the solar gain at source, from the sun trying to heat up areas of the floor, by swiftly moving that heat out before the floor has a chance to warm up and start warming up the house. It doesn't make the floor cold to walk, either, my other half tends to walk around on the travertine flooring in bare feet and reckons that at 19 deg C it doesn't feel at all uncomfortable.

We have travertine with no membrane, just bonded to the UFH heated slab with "flexible" adhesive. No problems with it, and no maintenance really. We sealed it when it was laid, but since then I;ve been working on the house, tramping mud in, generally making a mess, spilling tea etc and it doesn't seem to cause any damage. I sweep the worst of the mess off, give it a wipe with a damp cloth and it comes back looking as it did when laid. The only think to watch is that it can get scratched. The tiny every day scratches don't show at all, but I think you could cause a bad scratch it you dragged something over it.

It looks very much as we're all asking about the 4 cell unit, or the 2 cell add-on box.