Jeremy Harris

@MikeSharp01, I agree with all your points, but would add that we really have no need to keep re-inventing new low, or zero, energy housing standards. The Passivhaus Institut have a well-proven model and performance standard that has been widely used around the world for well over 30 years now. I'd never heard of nZEB at all until this thread, yet I subscribe to Passive House magazine and tend to read (and occasionally contribute to) web sites that focus on low energy design. To me this indicates that it's yet another standard dreamt up by someone who's out of touch with reality. All we need to do is follow the example of countries like Ireland, who have tightened their building regs to reduce energy use and, more recently, started to introduce the PassivHaus standard for all new houses built in Dublin. It isn't rocket science, but there does need to be a great deal of work done to get house building firms to accept modern methods of construction, with intrinsically good thermal and airtightness properties, rather than persist in trying to bodge older build methods to "just" scrape through Part L1, or very often fail to comply with it, as we all know is the case.

Corrosion resistance is an issue with just using glycols, so usually additives are needed to prevent corrosion in any system with a mixture of metals. In theory it shouldn't be a significant issue, as most heat pumps use a stainless PHE, and that's fine with copper pipework. The other thing that would make me want to have a look in more detail is whether or not the flexible hoses and rubber seals are OK with just plain glycol.

The problem is that heat pumps have a PRV that discharges to the environment, so the antifreeze/inhibitor has to be shown to have no adverse environmental impact and be non-toxic. Ours would just pour the contents of the primary circuit out on to the ground underneath the unit if there was an over-pressure event.

I agree - and our new home is better than zero energy, BTW, but wasn't designed to meet a load of Eurobollocks. It's just a well-insulated and airtight box, with effective heat recovery ventilation and a bit of zero carbon energy generation. I will happily bet that few self-builders are interested in spending loads of money to get some sort of additional certification, or comply with a particular, non-mandatory standard, but far more will want to build energy efficient homes for the least cost. Sadly, every single "standard" that's better than Part L1A costs money to prove compliance, money that I'd rather spend on making a more energy efficient home.

The MIs say flush and replace every five years. Adds a fair bit to the running cost, which is one reason I went for a low volume coil in a 70 litre, low temperature buffer tank, so I could just about get away with 10 litres of antifreeze/inhibitor concentrate (our total primary circuit volume is just over 40 litres).

Sadly, this matches my experience with local architects, with one exception. From talking with one very switched on local architect I've reached the conclusion that somehow there needs to be a melding of the artistic and design skills that architects have traditionally learned with hard-core systems engineering, so that more architects understand the fundamentally different design approach that has to be taken when designing an energy efficient home. I've recounted here before our experience with four local architectural practices. I wrote a single A4 page with a brief on it, that had nine bullet points, in descending order of importance for us. Bullet point one was that the house should meet, or be close to, Passivhaus performance. All four practices completely ignored this at the short initial meetings I had with them, and one suggested that we should include four large roof lights in the South-facing elevation. A bigger numpty would be hard to find, as even when I asked about the over-heating risk it was met with a blank stare, that suggested to me that the bloke hadn't got a clue about passive house design. The glimmer of hope is that there are a few architects around who are taking the time to get to grips with low energy design. One, quite near us, is like a breath of fresh air compared to the older, more established, practices (and we've now had thirteen different architects come to visit our build, so I've been exposed to a reasonable sample). We're not that far from the New Forest, either; it's around 40 minutes or so driving time away.

I think it does for a lot of Chinese stuff, far more of it just ignores the safety regulations then most people realise. Years ago I had a friend who had a business making custom bicycles and he imported almost all his components from either China or Taiwan. He went to Shenzhen in China to meet some suppliers, and sent me some photos of his trip. He spent half a day in one of the massive emporiums there, and one of the photos was of a stall that only sold stickers with things like fake CE marks, Windows and Apple logos, etc. I remember him telling me that it was very difficult for a small business to get manufacturers in China to adhere to any sort of standards, as they always want to try and reduce the cost by cutting corners. He gave up with getting components from China in the end, having experienced non-existent adherence to specifications, and now buys only from Taiwan, where it seem that manufacturers understand the need to stick to an agreed specification.

No, the PV inverter has a safety cut off, so as soon as the grid goes down the PV inverter shuts off. The grid needs to be up, within voltage and frequency limits, and with an impedance that is below the inverter cut-off threshold, for the inverter to switch on the output side. There's no need to turn off a PV system unless it's being worked on, usually.

The electrician that has installed/signed off your installation should have made sure that not only was there a proper earthing scheme fitted, but that it had been tested and was compliant with the regs. AFAIK, being off-grid doesn't exempt anyone from the regs - if the system is above 50V AC then it is an LV installation and the regs apply as they would for a grid connected system. For a generator or inverter powered 230 VAC system the requirements are that a local protective earth should be provided, in the same way as would be the case for a grid supply with no protective earth. The 230 VAC connection from the inverter should be connected via a suitably rated fused double pole isolator to the consumer unit, with the protective earth being provided by a TT system. This means fitting an earth rod, testing Ze to make sure it's within spec (no greater than 0.8 ohms normally) and using that as the protective earth for the installation. The consumer unit, or other distribution point, must have a double pole RCD or RCBO. The inverter you have looks to me as if it's a Chinese made unit, as it's marked 220V, yet it carries an EU CE mark, which is odd as the EU supply voltage standard is 230 VAC, not 220 VAC. Fake CE marking is extremely common, so common that I suspect there are more fake marks around than genuine ones. That doesn't mean the unit is inherently unsafe, although as it has a metal case and makes no mention of earthing one has to be just a bit suspicious. The case should be earthed, but it would be wise to check that the output is really isolated from the case before doing this. An electrician could test this in a few minutes, easily enough. Finally, there is usually an insurance requirement that any temporary LV supply (and LV is anything over 50 VAC and under 1000 VAC) should be installed, tested and signed off by a competent person. Even if an insurer doesn't require this, then it still important that it be done, particularly if a third party, like a contractor, is working on the house. Failure to have a properly installed and tested LV electrical installation, even a portable site system, could make you personally liable in the event of an accident. Edited to add: Looking more closely at the photos of that inverter, I can't see any shutters on the outlet. Well worth checking this, as a properly approved BS1363 outlet must have an earth-pin operated pair of shutters that close off the line and neutral sockets. If it's as I think, without shutters, then the CE mark will definitely be fake and it would be advisable to do some testing to make sure that it has adequate internal insulation and isolation between both the DC input terminals and the output terminals, and between the output terminals and the case. For use as a temporary, perhaps portable, supply then I'd suggest that the minimum requirement should be a decent earth rod and connecting conductor connected to the inverter earth, together with a plug-in RCD to provide protection to any user. Edited again to add: The seller gives a valid GB VAT number, but this traces to this flat: Member State GB VAT Number GB 243079218 Date when request received 2017/03/24 10:54:40 Name JUNFENG CAO Address FLAT 93, ADDY HOUSE ROTHERHITHE NEW ROAD LONDON SE16 2PD

I'd be interested to see what you find. I only started testing these when I had odd readings from two sensors that were both sat on the bench. I then clamped half a dozen sensors, flat side down, to a block of aluminium and calibrated them against an NPL calibrated glass lab thermometer that was stuck in a drilling in the aluminium block, with the drilling filled with heat sink compound. What I found was that there were often temperature offsets of between +/- 0.5 deg C to a worst case of + 1.3 deg C, at around 20 deg C. In general, only around half to two thirds of the Chinese DS18B20s were inside the Maxim spec of +/- 0.5 deg C. I didn't check linearity, as I decided to just give up on the Chinese sensors and use genuine Maxim devices. The only downside with doing this was that I needed to make housings for the Maxim devices, not hard, as I found they are a nice snug fit inside a bit of 6mm OD brass tube from B&Q. With 1mm OD heatshrink on the junction with the connecting cable I found it was pretty easy to run some quick set epoxy over the DS18B20 and insert it into a short length of brass tube, sealing around the cable entry with adhesive lined heatshrink sleeving. An extra blob of epoxy in the end of the tube sealed that and made a robust sensor. With regard to the pull up resistor, I found that reducing the value this gave better results on long cables. I'd very occasionally get a single duff reading, maybe once every week or two (and the sensors are read ten times an hour) from the sensor with the longest cable run. Reducing the pull up from 4k7 to 3k3 seems to have fixed this.

My experience is that the Chinese DS18B20 sensors have a relatively high percentage of duds, with temperature offset being the quick and dirty way to spot them. All the genuine Maxim DS18B20s that I've bought from an accredited supplier (RS Components or Farnell UK) have been far better matched, with no duds at all. Looking at the device marking, there are noticeable differences between genuine Maxim devices and the Chinese ones, and like a lot of Chinese semiconductors, I suspect they are fakes. The genuine Maxim devices are more expensive, but frankly that extra cost is trivial when you consider the time it takes to connect up and position the sensors in a house.

Make sure it's not included in either the design SAP or the as built SAP should be good enough, I think.

They are IP56, but as they are SELV, in effect (although they have no power supply, as such), then they are safe for use in bathrooms. The only thing to worry about would be whether they were rendered inoperable by water damage. I've taken one of the battery-powered HomeEasy switches apart and it was reasonably well protected from water ingress, and fairly well-sealed from condensation damage, so I'd say they are OK for Zone 2, possibly OK for Zone 1.

There shouldn't be any capacitors on the AC side of the inverter, but with no protective earth (!) the earth conductor won't be doing anything useful. With a DC to AC inverter (or generator) you must provide a protective earth with an earth rod or other connection to a known to be good protective earth conductor, to make the installation safe. The installation should be wired in a similar way to a TT mains supply system, with a tested and known to be OK earth rod providing the protective earth at the supply end, in this case the inverter AC output side. In theory a floating supply "could" be safe, as long as there is no possibility whatsoever of an incidental connection, or leakage path, that could mean that the inverter AC output terminals are referenced to local earth. Frankly I would NEVER want to go near a non-earthed installation like this, though. I know people often completely ignore the instructions to provide a protective earth when running generators - that does not make it safe. (The above photo is a joke, before someone makes any comment about it........................)

I've been tempted to buy some to replace the HomeEasy stuff, which was added to allow extra light switching in the kitchen, after the wiring had been done (and yes, there was some "influence" from someone deciding, long after the installation was completed, to make some changes...............). This system looks just as easy to use as the HomeEasy system, which also uses 32 bit encoding. The receivers can be programmed to receive codes from several switches, so we have four switches and three receivers, to allow different lighting combinations and a single on-off switch that controls all three receivers.

If it were me, then I'd officially make the garage an area that's outside the heated envelope, so you don't have to comply with Part L1 for it. You can then do pretty much what you like with the garage, practically, including fitting UFH and insulating it. Our new garage is detached, but well-insulated all around, and the insulated Seceuroglide roller door seals pretty well, but not to house-type standards. It has brush seals along each side and a soft hollow rubber seal at the bottom, that seems to seal pretty well to the concrete threshold.

Yes, I looked at them a couple of weeks ago, when they were discussed on another forum. My experience with the HomeEasy/Byron remote switches is that the practical range for us is around 2m to 3m maximum, not sure why, as I have the receivers mounted in the ceiling void, in direct line of sight with the transmitters, with just a layer of skimmed plasterboard (not foil-backed) between them. The Quinetic system uses the same frequency band, 433 MHz, but may be more immune to interference than the HomeEasy/Byron units, as they use frequency shift keying (FSK) rather than the amplitude shift keying (ASK) that the HomeEasy/Byron units use.

Unfortunately that switch is only rated for up to 50 V, so not safe for use at 230 V AC. The switches on decent quality 13 A outlets are usually double pole, but worth noting that some of the cheaper types of 13 A outlet only have single pole switches.

Having tried the strap on knee protectors and the foam pads in work trousers, I've reverted to using some very old commercial divers neoprene ones, the ones made of very thick wet suit neoprene. Mine are around 30 years old and were last used when I was caving regularly, but they came out of storage for the build. Unlike the strap on knee protectors, being fairly soft neoprene means that they don't rub the back of your knees as badly, plus they stay in place a lot better. I wore them a lot during the build, not so much for comfort, but because I have an artificial left knee cap and nerve damage that means I have no feeling in my left knee at all, so without knee pads I also end up with thing stuck in my knee that I only find later.

The earth connection looks OK, and the COB LED in this unit seems to be direct drive, via parallel connected BP5132H high voltage constant current driver chips. This arrangement means that the LEDs on the chip on board (COB) are connected in series and driven with full wave rectified mains. A side effect of this is that, like some GU10 LEDs, it's possible to get a slight glow from induced current in the wiring. What is puzzling is that the earth conductor in a three core cable should act to reduce induced current in the switched line to a very low level. Clearly it's not doing this in your case, so it's worth checking that there is continuity from the earth conductor in the LED to the protective earth for the installation, as it's possible that the earth has been disconnected somewhere. If all is OK, then the fix to stop them glowing is probably to fit a double pole switch. Big Clive has some details about this type of LED flood light on his YouTube channel:

I gave SSE meter readings (on request) last week. Today I had a meter reader around from SSE. I asked him why he was reading the meters, when they'd been read by him last September and SSE had asked me to take readings last week. He said that this happened all the time and that no one ever seemed to coordinate things within SSE.......................

I'll be interested to hear how you get on with Iresa, as I've just had a letter from SSE telling me that they have increased the tariff. I've just done a rough calculation and it looks like an increase of about 16%, which seems OTT to me.

You may find it difficult to take apart whilst retaining the refrigerant circuit intact, best bet might be to see if you can take a good look at one first. On one of my boats I made a cold locker, originally just an insulated locker with the bottom being the skin of the boat, so the water kept it cool. That worked OK for things like milk and butter. I later converted it to use a Peltier cooler, with a bit of 3mm stainless plate sikaflexed to the outside of the hull as the heat sink. That kept the locker a lot cooler, but used a fair bit of power (around 2 to 3 A at 12 V). If you have gas on board, then a camping fridge might be an option. These are absorption fridges that use a small gas flame to keep the refrigerant circuit working, with no moving parts. Sounds counter intuitive but they work OK. We hired a yacht on the Norfolk Broads a few years ago that had one of these top loading gas fridges built into a cockpit locker (to keep gas out of the inside of the boat) and it was fine for two or three days worth of milk, butter, bacon etc.

Just to add that I found the post showing photos of the unconnected earth wire in similar Chinese LED flood lights: With an earth conductor connection made to the case these lights are safe enough, and seem reliable.

The main difference is that these LED flood lights are already earthed (or should be), as they have an alloy case. The GU10 LEDs are (supposed to be) double insulated, with no earth conductor connection, so induced current in the switched line can make them glow, with the return being via the non-switched neutral. Fixing that problem is usually fairly easy, just make sure the earth conductor in the feed to the LEDs is connected to earth, even though it's not used as a protective earth at the LED end. Doing this stops the tiny induced current in the switched line (or rather, just gives it a lower impedance path via the earth conductor) and stops the slight glow.