Jeremy Harris

The floor areas on a rdSAP created EPC will probably be in error, though. Ours is over 10% out, and that's after I gave the assessor a scale plan with the correct floor area marked on it, along with the dimensions. If the assessors doing house sale EPCs are as crap as the one that did ours (at the place for less than ten minutes, didn't take a single measurement or even check the obvious stuff, like the loft insulation) then I doubt that the area on an EPC means much, TBH. If any houses have had extensions or loft conversions there may well be plans lodged on the local authority planning website, though, and they may be good enough to use, although may not be accurately scaled.

There's a good reason they are colloquially known as Staffordshire Blues, as that's the colour that they end up when fired to near-ceramic temperatures using Staffordshire clay, which was always the traditional clay they were made from. That's just a hang over from the Industrial Revolution and the way that the technology for firing at controlled high temperatures came out of the Staffordshire potteries industry. The use of "engineering" bricks came about from the need for bricks with a high compressive strength and high resistance to weathering during the Industrial Revolution. for everything from canal locks to the mounts and buildings for things like big steam engines. Traditionally, ordinary "house" bricks were made near to, or on, the actual building site, by itinerant brick makers, who used local clays and fired them in open fires, which is why we have such a wide variation in "heritage" brick colours. If your interested, there is still one itinerant brick maker left in the UK, who has an interesting web site about bricks: http://ajmugridge.co.uk/

You can certainly run a temporary, or permanent, supply to an enclosure in a wall, fence or whatever. Several here have done just this (including me). As long as there is a signed off installation on the consumer side, then the supplier will fit a meter. The DNO (or NIE in NI, I believe) will happily install a supply to a company fuse and head in an approved box, even if it's mounted in a fence, as ours is. The consumer side installation doesn't need to be anything grand - mine's a fused isolator switch, a small 4 way (two doubles) consumer unit, that then feeds a caravan site consumer unit that has a 16A Commando socket. That was my temporary site supply that we ran extension leads etc from. I didn't want the meter box in the wall as, and inset box it would have compromised the insulation and created a thermal bridge, and a surface mount box would have looked ugly, hence the reason for mounting it remotely in the fence that eventually became our wheelie bin screen. Doing it this way meant not paying twice for the installation, too. I paid once to have a supply put in and my electrician just switched things over to power the house when we were ready. The only slight oddity is that the DNO insist that the supply use TT earthing whist it was being used as a site supply (as they do for mobile homes) and could only be switched over to TN-C-S once the house was connected and ready for testing. Daft really, as the TN-C-S earth impedance was lower than the TT impedance, and the site supply was being used exactly as if it were an extension lead from the house, but they make the rules so you have no choice but to stick with them. As it happened, I reused the TT earth rod etc in my workshop, anyway, so nothing was wasted.

The basic rules with a self-build (England and Wales, Scotland and NI are different) are that for the house itself you can either use a Part P approved electrician for the installation, who will do the paperwork as he/she goes and issue you and building control with the installation cert at the end, or, in theory, you can do all the wiring installation yourself and request that building control inspect and test to Part P.*** This doesn't really apply to a mobile home installation, though, where you will need an electrician to do the installation and issue a certificate anyway, as it doesn't fall within the building control rules for a new dwelling or other work requiring building control approval, AFAIK. *** The fly in the ointment is that some building control bodies are unable to do the required inspection and test of an electrical installation. To some extent this this is a bit of protectionism by the commercial bodies that operate the Part P accreditation schemes - they are reluctant, it seems, to approves electricians to inspect and test third party work only. I ran into this problem, as our building control body admitted they were not able to inspect and test an electrical installation and knew of no electricians in the area that were accredited to do so. I can understand the reluctance to wish to sign off third party work to some extent, as much of the cabling will be hidden from view and unless an inspector makes several visits he/she would have no way of knowing if the cabling was being run in safe zones, was being de-rated for grouping and insulation, was adequately supported as required by the regs, etc. This scuppered my plans to wire the house myself, so I ended up having to use a Part P accredited electrician.

Take care with where you site and operate valves! I've heard of someone who put a shut off valve at the dam end, and when the valve closed the suction from the momentum of the water still rushing down the pipe squashed a bit of MDPE flat (large bore, too think it was at least 63mm). Valves at the bottom can also be tricky, apparently, as stopping a moving column of water can create a pretty high pressure pulse (it's how pulse pumps work - I helped fix a Victorian one once, that was sat in a small stream).

Use SWA and bury it directly, no real need for conduit if you're going to leave the cable there afterwards. Needs a Part P installation and sign off, BTW (assuming you're in Part P land), so not a DIY job.

The site that I think that @Alexphd1 got that image from is this one, that lists all the parts and their prices: https://www.alma-solarshop.com/94-integrated-mounting-system-easy-roof-gse These people seem to do all the parts, too: https://zerohomebills.com/product-category/solar-photovoltaic-pv/solar-accessories-and-mounting/mounting/

From memory, the parts needed, apart from the trays, are side flashings (pretty simple thin black anodised aluminium, bent to fit the side ridges on the trays and with a small upstand under the slates/tiles at the sides), top flashings, again, pretty simple aluminium flashing that goes under the slates, tiles at the top (and ends up hidden), and simple clamps that hold the panels down to the additional bits of timber batten that have to be laid where the fixing points are. TBH, it's not a very complex system and some of the special flashing can be replaced with ordinary non-lead flashing anyway (at the top and bottom, for example). The key parts needed are the trays, the panel clamps and EPDM gaskets, the wide-head screws (that also have EPDM washers) and the side flashings. The rest can be done using off the shelf stuff. You can probably substitute ordinary metal roofing screws and washers for the ones they use

I wonder if it's worth investigating a group buy from a French retailer? It seems that the GSE Integration frames are £35 each here (plus the cost of the flashing and panel mount clamps - although the flashing is nothing fancy and could easily be made up from standard alloy stuff). If things are as they often seem to be here, and there's a big markup for stuff sold in the UK, then I wonder if it'd be worth trying to buy them from France? In many areas of France there are laws/regulations that mandate the use of in-roof panels (presumably why the two main manufacturers are French). Might be worth finding out if they can be bought more cheaply over there. I (and @PeterStarck) saved a great deal of money by buying our MVHR units from Denmark, rather then the UK - they were thousands of pounds cheaper when bought from there. Maybe the same applies to the in-roof panel mounts. Using a purpose made mount gets around the SE fees for the structural integrity stuff as well.

Ours swelled a bit at the joints, where water got in to the end via the T&G joints (we also had torrential rain for a day whilst the frame was going up, so everything got soaked). I just hit it with a belt sander to take the raised bits off, once it was dry and before I PVA'd the whole lot.

Possibly, but equally it may reflect back up a fair bit of heat to the underside of the panels. making them even hotter. I think I'd want to have as deep a ventilation space under the panels as possible, as they do get pretty damned hot. It'd be a shame to save a load of money on the mounts, just to bugger up a set of panels, or degrade their performance.

Roughly 36m2 , but you definitely need the big ventilation cut outs, as without them I reckon the panels will seriously over heat. As it is, in-roof panels tend to run pretty hot (it's not uncommon for our panels to hit 50 deg C), so there needs to be plenty of space underneath the panels to allow air to flow up and under them on a hot day, plus keep the rain out when it runs down behind the panels.

If you were to get a few sheets of OSB, cut out the big holes needed for ventilation under the place where each panel is to fit (these also allow the cables to connect up), add some small battens to form up stands around the big holes that you've cut out, add panel mounting ridges with battens in the same way (the panel frames just slot over the raised lips and are held down with alloy clamps and screws) then lay up GRP over the whole thing, finish with gel coat and wax to give a good weather resistant finish, you should be able to make a mount that will work OK. Whether it's cheaper than just buying the GSE/EasyRoof mounts I'm not sure. There would be quite a bit of work in cutting all the big ventilation holes out and adding up stand frames around them all to deflect water out and around to the edges. As mentioned above, it might be worth looking at making a mould up to get some mounts vacuum formed. There used to be a place somewhere near Thruxton that did custom vacuum forming, and a timber mould is fine and would be pretty easy to make. Not sure what custom formed ABS mounts would cost, but might be worth looking at. The GSE mounts just slot together, with the U channel on one side being wider than that on the other, so they fit over each other. They do have water deflection barriers underneath, above the big ventilation/cabling cut out that are designed to deflect water out to the sides and keep the bit of plastic at the top a bit stiffer.

Been discussed a bit here: Probably do-able, with a bit of thought about the detailing. I'd be inclined to go for GRP over an additional layer of OSB, and ideally try and copy the big cut outs with raised edges that the GSE and EasyRoof mounts use, as they help a lot with keeping the panels well-ventilated I think (another reason for going with GRP - easier to make up stands, perhaps).

I'm near-certain it's to reduce the risk of icing. It's the high Δt that seems to cause the heat pump to work hard, and so cause the evaporator temperature to reduce to a low level, perhaps to sub-zero temperatures where it will tend to ice up. Space heating with UFH is generally a very much less demanding requirement - in our case in space heating mode the heat pump runs at around it's lowest possible modulation level, typically around 400 to 600 W of input power. That power increases rapidly when the set flow temperature is increased, I've found. My guess is that your unit may well rely on the lower heating load to act as a de-icing system for the DHW mode, by letting the evaporator warm up naturally when the load is reduced. FWIW, I've never actually seen ice on our unit's evaporator, even when I was playing around to try and see how it behaved. It would go into a de-icing cycle before there was any visible indication of ice, just loads of condensate dripping off the evaporator. It may well be that it does this as a pre-emptive measure, as there may possible be a risk of damage if ice does build up; there isn't much clearance between the evaporator and the rear screen.

Our guys had a special tooth with a bloody great shackle welded to it that they bolted on when needing to lift stuff. I doubt it had been anywhere near a lifting gear test or certificate, but having the load attachment right out at the end of the bucket did seem to give a give a fair bit more manoeuvrability with the load.

From what I can tell, they may well not be that intelligent. Our's seems more intelligent than some, as it does at least have an external temperature and humidity sensor, that senses the air flowing into the evaporator, plus it senses the evaporator temperature (or more accurately, the refrigerant temperature flowing in/out of the evaporator). If there was an easy way to detect when there actually was ice on the evaporator and then only use just enough heat to get that to start to melt and fall off, then i'm pretty sure there would be a worthwhile energy saving. As far as I can tell it just relies on a timed cycle, though.

The air flow rate at normal MVHR background ventilation rates is low, typically no more than one whole house air change every couple of hours. We have a 1.5 kW duct heater/cooler build in to our Genvex. Yes it is just about enough to heat the house, and provide a bit of comfort cooling in hot weather, but it's extremely slow to change the house temperature and left to it's own devices the Genvex controller will just put the MVHR into boost mode in order to try and circulate as much heated/cooled air as possible. It does work, and because the house has a long thermal time constant we could get away with using it as a gentle background heating system, but I find the air a bit dry when it's in heating mode and downstairs there's a very significant benefit from having the UFH heating on. Somehow, having very slightly warmer feet adds to the perceived comfort level a fair bit.

Yes, I spent hours testing our unit to see how it behaved. As it's a big name manufacturer (one that's re-badged and sold under a fair few other "brands") it seems reasonable to assume it behaves much like other units - there's only so many ways to skin this particular cat. What happens (or seems to happen - remember this is test-derived, so there's guesswork as to what the ASHP is doing internally) is that when icing conditions are detected (doesn't actually have to be ice on the evaporator, either - spoofing the sensors makes it do it) the unit enters a defrost cycle. The 4 way reversing valve operates and the ASHP runs at max power for a few minutes, drawing heat from the house (i.e the condenser becomes the evaporator and water at around 10 to 12 deg C gets sent around your UFH/buffer tank). It stays operating like this for a time, then switches off, operates the 4 way reversing valve again and re-starts at the modulated demand required to deliver the set flow temperature (the unit power is modulated up and down in order to maintain the set flow temperature when it's switched on and in heating mode). So, a ten minute defrost cycle can remove more heat from the house than ten minutes running at the normally modulated down power level. Clearly during a defrost cycle the ASHP is removing sensible heat from the house, and for several minutes after the end of the defrost cycle the ASHP is playing catch up and replacing the heat that it drew out in order to defrost, before it gets back to being a net contributor to heating the house again. All the energy it consumes from the start of the defrost cycle to the point where it's replaced the energy lost from the house as a part of the defrost cycle is wasted, in effect, and if it's defrosting once every hour or so (not untypical if run hard in ideal icing conditions) then it may well be wasting 20 to 30% of the energy that would otherwise be used to heat the house, so lowering the SPF.

@pdf27, Δt doesn't seem to be the problem, or at least not the most significant problem, the dominating factor is that ASHPs need to defrost if they are run under conditions where the evaporator can ice up. A defrost cycle reverses the 4 way valve, so putting the heat pump into reverse, so that if it's in heating mode it will switch to cooling mode, and pump heat out of the house in order to warm up what had been working as the evaporator in order to melt any ice that may or may not have formed on it. The way in which an ASHP manages defrost cycles has the most significant impact on SPF during cool, humid, weather. Once the air temperature drops below zero the SPF actually increases for an ASHP that is being run to the point where it's been reaching the ice forming region, that combination of incoming air temperature and humidity and evaporator temperature that creates an icing risk. It is this that means that COP is such a poor measure of real-world efficiency - one ten minute defrost cycle can lose 20 mins worth of heat energy to the house, with a commensurate loss in efficiency, which is not reflected in the COP data. I found that our Carrier ASHP measures the air temperature and humidity that is being drawn in to the rear of the evaporator and uses that, together with the evaporator temperature, to determine whether a defrost cycle was needed. It also seems to use the actual heat energy that the ASHP is delivering in that determination, as I've found, by experiment, that restricting the flow temperature to 40 deg C maximum seems to completely stop the unit from ever defrosting. My best guess is that the heat energy being delivered with the flow set to that low a temperature isn't enough for the defrost sensing system to trigger a defrost cycle - it probably relies on the unit being able to defrost naturally as it cycles, perhaps. Worst case I found was when the air temperature was around 4 deg C and the humidity was very high, a not untypical wet winter day in the UK. My best guess is that when the compressor turns off under such conditions, there is enough sensible heat in the cool, moist air to defrost the evaporator from just the fan airflow, with no need for the 4 way valve to operate and start pumping heat out of the house.

The major issue to address is the thermal time constant of the house. Insulation is a part of this, but perhaps more important is the combination of the heat capacity of the inside of the house (to a maximum of around 100mm depth from the internal wall/ceiling/floor surface) and the thermal conductivity of that same layer. It's also important to ensure that the insulation doesn't just have the right U value, but that it has a nice long decrement delay. The idea is to delay heat getting in or out of the house so that the natural diurnal variation in temperature isn't reflected by similar cyclic changes inside the house. In our case, the combination of a fair bit of sensible heat stored in the concrete slab, which also has a pretty good thermal conductivity, plus the use of a relatively thick layer of high'ish decrement delay insulation in the walls and roof, result in very slow changes to the internal house temperature. This makes it relatively easy to maintain the house at a steady temperature all the time. Most of the heat stored in our house comes from the slab and the plasterboard (plasterboard is better at storing heat than concrete - gypsum has a higher heat capacity than concrete).

Run the cable in conduit, perhaps?

Gloves are a good idea, but both MEK and acetone tend to permeate latex gloves slightly and both DEFINITELY remove most types of nail polish! Just a wipe should give an idea as to whether it will remove it. Both acetone and MEK evaporate very quickly, so it's hard to get the stuff to stay on a surface for long.

The guys that fitted our stone worktops used either acetone or MEK to clean them after fitting, so I'm pretty sure they are OK on stone surfaces, just watch for spillage as both will attack a wide range of plastics, paints, varnishes and even silicone based sealants.

The problem with putting pipes in the walls is people like to bang nails and screws into walls to hang and fix things. In practice, cooling the floor works very well, better than I expected, and I suspect that's because air in an occupied house tends not to stratify very well, and is almost constantly moving around, especially with MVHR.