Jeremy Harris

Block will be pretty good at keeping out airborne noise, but not so good at ground-transmitted low frequency "noise", so it really depends on how much of the railway noise is airborne and how much is vibration transmitted through the ground. Reducing sound from vibrations transmitted through the ground really needs flexible isolation, with the isolated structure having enough mass to ensure that it has a resonant frequency that's a lot lower than the lowest transmitted frequency, which may not be that easy to build. A surprising level of sound comes in through tiny air gaps, too, I've found. I can say that blown cellulose insulation between two, fairly well isolated, stud walls seems to be incredibly good at reducing external sound penetration, something that I wasn't expecting. Our new house is, if anything, too well sound insulated, as you can't hear anything going on outside, not even a Chinook flying overhead, when the doors and windows are closed and latched. Whenever I have heard a sound inside it's always been because a door has been closed, but not latched tight to its seals. It means that even a truck coming up the drive can't be heard inside, let alone a car. If you go for a stud wall, then I'd be inclined to fill it with dense insulation and try to isolate the skins on either side. If you go for block, then it will probably give better airborne noise reduction, but may be a bit worse at reducing structurally transmitted sound. An example of this is the way sound like a light switch click may well be clearly audible from the other side of a block wall - something that's noticeable in our old house, that has block inner walls, but isn't noticeable in the new house that has acoustically insulated standard stud walls.

You can do this, and our ASHP has a DHW setting, via dry contacts or the programmer, so that it can receive a call for DHW and increase the flow temperature to 55 deg C. In practice you're better off using an immersion heater during the cooler, damper, months, though, as the ASHP runs around three or four defrost cycles per hour in cool, damp, weather and the real-world COP (not the highly optimistic dry air COP often quoted) drops to close to unity. I ran a lot of experiments with our ASHP, to try and understand how it worked. Ours has an outside air temperature sensor and a humidity sensor and uses these to determine when there is an icing risk and when to run a defrost cycle. When defrosting it goes into cooling mode, drawing heat from the house or hot water system to warm up the heat exchanger and melt any ice. A typical defrost cycle takes around 10 minutes, so any more than three defrost cycles per hour takes you into the region where the real world COP is at unity or below. The main factor seems to be humidity, rather than just air temperature, so the worst performance isn't in cold weather, it's in cool, wet, weather. Sadly, we seem to get a fair number of days in autumn, winter and spring where the humidity is high enough to cause a problem. The solution was to not use the DHW capability of the ASHP and set it to a maximum flow temperature of 40 deg C. At this flow temperature it never seems to need to defrost when meeting our pretty low heat demand, so always gives a pretty good COP, better than the published data would suggest most of the time, I think. The best solution for heating an DHW from an ASHP seems to be to use a hybrid, like the Daikin Altherma. They use the ASHP part for pre-heating DHW and running the heating system, with a gas combi to boost the DHW. The big advantage is that one of these uses much less gas than a conventional combi system, because most of the "heavy lifting" is down by the heat pump taking the water to within about 15 deg C of the required DHW temperature, so it is a reasonable option for running from LPG.

I used a couple of the fairly large DIY two-pack foam kits a few years ago, to insulate the inside of steel-hulled canal boat a friend was building. Pretty easy to use, once you've got used to the way the foam reacts under different conditions. A few degrees warmer makes it expand a fair bit more, so the trick was to try and guess the expansion room needed as the inside of the boat (which was in a big shed) warmed up. By the time we'd finished we'd both got pretty good at guessing the expansion rate, so there was less waste from the end we finished at than the one we started at.

We planted 300 bare root native hedge plants around our plot about two years ago. The curious thing was that they sat there looking as if they were dead for the first year, then suddenly came to life last spring. Ours are a mix of blackthorn, field maple, hazel, wild rose and hawthorn, I think. They are just coming into bud now, and I'm hopeful they will do better this year than last, as last year they were struggling with some of the more vigorous weeds that had established themselves whilst the hedging plants were having a "year off".

Instant water heaters are near enough 100% efficient, in terms of calculating the temperature rise for any given flow rate and temperature differential, but as there are two variable here, then both need to be known to calculate the temperature rise. Some examples, given as a temperature differential for a range of flow rates, for the 9.6 kW maximum unit we have: 5 litres/minute = 27.3 deg C rise 6 litres/minute = 22.7 deg C rise 7 litres/minute = 19.5 deg C rise 8 litres/minute = 17.1 deg C rise 9 litres/minute = 15.2 deg C rise 10 litres/minute = 13.6 deg C rise 11 litres/minute = 12.4 deg C rise 12 litres/minute = 11.4 deg C rise 13 litres/minute = 10.5 deg C rise 14 litres/minute = 9.7 deg C rise 15 litres/minute = 9.1 deg C rise This illustrates well just how much power you need to heat water to a reasonable temperature with an instant heater, and why electric showers can only deliver a pretty low flow rate (typically less than 5 litres/minute) compared with a shower heated by something like a decent combi boiler, with 30 kW of more of instant heating power available. For a low energy house, where tank heat loss can be a nuisance in summer (as our old thermal store proved to be) there is some merit in looking using a low temperature warm water tank, say, around 35 to 40 deg C (plus an anti-legionella boost every couple of weeks to 60 deg C) and then just using instant heaters to boost this warm water to, say, 50 to 55 deg C on demand. The losses of such a system are a lot lower; a tank at 40 deg C in a house that's at 20 deg C will have half the heat loss of a tank at 60 deg C in the same house, for example. In our specific case, the pre-heated incoming cold supply can drop to about 29 deg C before the instant water heater can no longer deliver 42 deg C at 10 litres/minute, about the lowest acceptable shower temperature and flow rate for us. This means we can squeeze more useful heat from both the Sunamp PV heat battery and the 70 litre buffer tank, as the combined output from both can drop to around 15 deg C lower than would be acceptable for a shower, because of the added boost from the instant water heater. Edited to add: Thanks for the edit, Nick. Whatever was in that big blank space at the bottom just wouldn't delete for me, no matter what I tried

I can't see any reason why the silencer and manifold can't be the same box, if you can make room for a combined unit. One of my home-made silencers (the one that's almost hidden from view) is an MDF box sat directly on to the 150mm stub that comes out of the manifold. The flow adjustment discs fit to the HB+ manifold connections, and are secured in place by the quarter turn locking ring, so it would be challenging to get them to fit.

I would also say it was needed for site security at the moment, as building sites are dangerous and you have a duty of care to prevent "accidental" entry. Then I'd argue that the hedge you are going to plant is intended to be like that on the opposite side of the road, but until it has established itself and grown to the required height (and hedges, aren't subject to the same daft restrictions as fences - I have no idea why) you need the fence in order to prevent your young children from running out into the road. I don't think an enforcement officer could realistically do a thing right now, and would almost certainly just note the situation and mark the issue as dealt with.

Hi Dee, glad you found us OK.

Sad to hear this, but not surprising, given the massive cliff that has to be climbed to get a reliable product like this to market at a reasonable price. Pretty much all the existing battery core technologies have been around a long time now, yet very few seem to be able to get beyond the engineering prototype stage and into large scale production. It's taken lithium ion chemistry cells around 26 years to get from initial production to large scale adoption, and even now development is still improving ion exchange cell chemistry and construction, so I think it's probably reasonable to say there's likely to be around a 10 to 20 year period from first commercial production to a large scale reliable battery system being available. The big hurdle for any off-grid storage system is going to be the cost of storing energy. Current lithium-based ion transfer energy storage solutions seem to all be limited to at most a 15 year service life before cells degrade to the point where they lose too much capacity to be really useful. So if weight and size isn't an issue (and, unlike vehicles, it probably isn't a concern for domestic off-grid systems) then it probably makes more sense to go with cheaper and well-proven cell chemistries, as they are likely to have a lower whole-life cost. The really big problem with this is that the big demand for batteries is electric vehicles, so that's where the development funding is going, and electric vehicle batteries have a completely different set of key requirements, with being small and light being close to the top of the list. The only country that seems to be looking at off-grid energy storage pragmatically seems to be China, as far as I can see. They have a pressing need to generate more electricity and yet reduce pollution levels, so are spending very large sums of money on alternative energy generation and storage. Interestingly, they seem to have been developing a mix of two battery types, longer life lithium ion cells, plus they're manufacturing ancient NiFe cells again: http://www.changhongbatteries.com/ .

Reading the NIE website, it seems that the rules are much the same as here in the rest of the UK, with a G59 system being allowed in much the same way, except they do it through a staged proposal system, so you would need to make an application for phase 2 of the approvals that are being given: http://www.nienetworks.co.uk/Connections/Generation-connections/Small-scale-generation You can fit up to a nominal 11.04 kWp under G83/1, though, as long as you don't exceed 16 A per phase (the G83/1 limit).

My only encounter with an enforcement officer was over a public footpath that had been moved a fair distance and was crossing the first plot we tried to buy. He was a pretty pragmatic chap, who seemed reluctant to take action and would rather the two parties involved (not us, the vendor and the neighbour) resolve the boundary problem between them and then put in an application to change the route of a footpath if need be.

It's a good example of people going out of their way to cause a nuisance about something that doesn't directly affect them, something that some seem inclined to do just because they enjoy complaining......................... As above, it almost certainly won't be a planning issue. We've done much the same by erecting a post and rail fences in front of, and behind, boundaries that have hedges (or will do once the hedge plants have grown). In our case I told the planning officer that we were putting in post and rail fencing, with wire mesh behind, in order to secure the property and allow the hedges to get established. I was told that as long as it complied (more or less) with the rules mentioned above then it was fine. It was suggested, by the planning officer, that I might want to make the fence alongside the lane a bit higher than 1m, as in his view there was no highways visibility issue, it being a very narrow single track lane that has virtually no traffic on it. Our fence behind where the hedge will be is a bit over 2m high, from the level of the lane, as it's on top of a steep bank, but that's fine as it's not a boundary fence.

That looks suspiciously like drain pipe! Had we been staying in the old house then I think I'd have looked at fitting one of these, as we have a clear stretch of wall with no windows above the boiler flue, right up the end gable.

Yes, it does depend on wind direction, but both our new build and the old house are at the bottom of valleys that run more or less east/west, so the wind is almost always from the west, as a consequence of the prevailing wind direction in the UK and the impact of the local topography on surface wind. Our experience at the old house is that the flue gases get blown downwards pretty much all the time. We have our wheelie bins up against the wall beneath the boiler flue, which is around 2.4m above outside ground level, and if we happen to be standing there when the boiler fires we pretty much always get a brief smell from the flue. A lot will depend on how the air tends to flow around the house, but I'm not sure you can always rely on the flue gases rising, mainly because they aren't that much warmer than the air a lot of the time, especially for the few seconds after the boiler fires, when it's really just the fan that's pushing air through the boiler, that's sucked in from outside..

If you can find a G83/1 inverter that will accept around 32 panels at the DC input (assuming around 250 Wp/panel), then what would happen is that the inverter would start up earlier and shut down later each day, and so increasing the duration, but not the magnitude, of PV generation. There would be no excess, or extra, this would still be (under NIE rules) a 16 A, G83/1 installation. Similarly, you would only ever be able to self-consume up to the limit of the inverter, so 16 A at whatever the grid voltage happened to be at that time. Off the top of my head I'm not sure if there are any G83/1 inverters that can accept 32 panels at the DC side, but there may well be, as a lot of inverters are pretty flexible and programmable, so it's possible that there is a higher capacity inverter than can be programmed to work as a G83/1 one, during installation.

I'd suggest that getting as great a separation from the boiler flue and the MVHR fresh air inlet would be a good thing, irrespective of the regs, and also try and make sure the boiler flue is usually downwind of the MVHR inlet, if possible. Our old house has the boiler flue above, and about 2m horizontally, from the back door. This is within the regs, but less than ideal, as we get a definite momentary smell of gas in the kitchen if the back door is open and the boiler fires up. The back door happens to be almost always downwind from the flue, so the momentary release of unburned gas during ignition is enough to create a small nuisance. The boiler is working fine, and it's normal for there to be a short duration emission like this as the boiler fires, but I think I'd not want any risk of that getting sucked into the MVHR.

Our experience with SSE was that there was no charge for the request to fit a G59/3 PV system of more than 16 A per phase (and it's a current, not power, limit, with the closest approximation to power being 3.68 kW, but this is local grid voltage voltage-dependent). They granted me permission to install a G59/3 system (~6.25 kWp) very quickly and with no hassle. Here in the rest of the UK a system that doesn't require prior DNO approval can be installed under G83/2, in NI the standard is still G83/1. NIE still allow a three phase, 16 A per phase, connection under G83/1, so roughly around 11.04 kWp of installed capacity. Note that the limit is technically the installed capacity, and that NIE are clear that it is the inverter current limit that defines this, not the panel peak capacity. As long as the inverter is set to limit at 16 A per phase (as all G83/1 inverters should be) then you can install as many panels as you like, within the voltage limit of the inverter DC MPPT input(s). It can be useful to over-size the PV array and limit using the inverter, in terms of getting a longer period of useful generation through the day. Finally, many inverters (I suspect most, now) will soft limit at 253 V rms on the grid side. Ours does this in summer, and all that happens is that the exported power is gradually reduced as the inverter holds a steady 253 V rms at it's grid connection terminals. If you have a high grid voltage (as we do) then this caps your export without needing any intervention by anyone.

Given that we have 3 bar of incoming pressure, the 15mm on the instant heater has no noticeable effect on flow rate at all. I did flow tests with it in place and could get over 20 litres per minute (I think the bath tap was delivering around 24 litres/min before being temporarily restricted to meet building regs). In reality we're never going to pull more than about 10 litres per minute from the DHW system, most probably less than that when cold mixing has been taken into account at the shower mixer, so it's not a problem at all. Our old house has a 15mm cold rising main, that runs both the hot and cold systems, with all the pipework in 15mm, and that's perfectly OK in practice, in terms of flow rates at all the taps, shower etc. The only thing with using all 15mm like this is that there is a little bit of flow noise when the bath taps are fully on, but other than that there's no noise, and we rarely use the bath, anyway.

My understanding is that the smart meters effectively have two metering systems. One is the standard metering system that used in pretty much all electronic meters, and does do pretty good power factor correction. This is used internally to run the standard meter part of the meter and is to the same accuracy standard as any other meter. The other is the remote display data transmission, that is supposedly "instantaneous" power. I used an electricity meter chip as the front end for my excess PV diverter, and that samples at 900kHz with a 16 bit resolution, on both the voltage and current waveforms, so does a pretty good job of coping with things like switched mode power supplies, etc, that have a fairly nasty current waveform. This bit of the meter is pretty standard and is the "master meter", if you like, that runs the display on the smart meter itself and logs the energy usage to internal non-volatile registers. The second part is less accurate, as it has to be in order to be able to transmit "instantaneous" power usage to the indoor display. The problem is one of integration time, as I found when making my own wireless indoor display. The way the metering works is based on measuring true energy, in Wh, and so to get "instantaneous" power you have to choose an averaging period to convert Wh to W. In my case I chose 10 seconds, as a reasonable compromise between accuracy and display functionality. I don't know what averaging period smart meters use for the remote power display, but it's likely that they do something similar. If I were to calculate energy from the power averaged over 10 seconds at the internal display, in order to be able to make that internal display show Wh, or cost, there would always be an error. Over time, that error would get larger, as the internal wireless display doesn't know the total Wh recorded in the registers inside the master meter chip. There is a way of reading these registers, and it may well be that a smart meter can be interrogated to get an accurate energy reading, which may well be very different to the reading on an internal display. Interestingly all the meter chips I looked at had bidirectional energy metering internally, so could easily be used as export meters if need be.

It'll be a tiny bit warmer, but no warmer than standing on a bit of floor in bare feet would make it. There's really no problem, in terms of potential floor covering damage, as the temperature will always be a great deal cooler than with relatively high temperature UFH.

The foil would only get corroded by concrete, anyway, so there seems no point in having it if it's in contact with anything with cement in.

I'm pretty sure that normal consumer law applies here, so that the responsibility for resolving the problem rests with your supplier, as it's them you had the contract with. If they've chosen to ask their insurer to handle this, rather than them pay you themselves, then it is up to them to deal with their insurer, not you, I would have thought. The claim is well inside the small claims track limit, and you can do the whole job of making your claim online, for a reasonably modest cost, and you can, I believe, include those costs in your claim. I've only ever once had to resort to using the small claims court, as it used to be known years ago, and even then it was a very straightforward thing to do yourself, with no real need for a lawyer, as there is usually no formal court hearing, as such. In your case you have more than enough evidence, from the sound of things, so it would be just a matter of submitting that with the claim details and letting the court sort it out. It's quite rare for there to be a formal hearing; in my case the informal hearing took less than half an hour, sat around a table in a room at the back of the court building, with just the recorder, myself and the person representing the company I was claiming against. There was no hassle or unpleasantness, and no legal language, the recorder just stated that he'd read the claim details and evidence from both sides, had concluded that the claim was justified and gave directions for the company to pay the full cost of my claim plus the court costs. No evidence was heard during the hearing and the company were given 14 days to respond, IIRC. They just sent me a cheque within a week, and I then had to write to the court telling them that the matter had been settled. I believe that, by paying promptly, the company concerned avoided having a judgement formally recorded against them, which was almost certainly why they just paid up.

Sadly I rather think this is the standard line from many insurers. It sounds very like my experience of trying to make a claim on an NHBC warranty years ago. My lawyer at that time advised that they were very likely to just keep delaying things until we gave up, as apparently many people do just give up in the end (we did - we paid to get the defect, also a roof leak, fixed ourselves and I made good all the internal water damage). You could try the small claims track in the county court, with a claim against the roofing company. Quite why you're having to deal with their insurer I don't know, as the issue is between you and the supplier, isn't it? It should be the supplier dealing with their insurer, not you, I would have thought, as it seems it was their decision to hand the claim over to them, not yours. As for Aviva, all I can say is that they are a shambles, in recent experience. We have had contents insurance with them since they were Norwich Union, and because the premium wasn't much I never bothered to shop around. Last year I started getting odd letters from Aviva asking me if we were insured with them. I rang them, rather concerned that they had my name and address but didn't seem to have a record of the long-standing policy we'd had with them. They explained that they had "been having problems with transferring policy records due to a new computer system", apologised and confirmed that we were insured with them. Just before Christmas we had the same letter arrive again, asking if we had a policy with them and if so to contact them. I went through the same rigmarole, but this time I was a damned sight more angry. They apologised again, and said they had, once more, updated their records, and as a good will gesture they knocked £50 off this years premium. One things for sure, I not even going to think about renewing the policy with them again, as I have this horrible feeling that if we ever made a claim they would try and deny that we were insured by them......................

Same here, the economics just don't add up. One issue worth looking very, very carefully at is the battery warranty. I haven't read the small print for the Tesla system, but the 8 year warranty on the lithium ion battery in my car doesn't cover "normal range reduction as a result of battery ageing". I believe that the Nissan Leaf battery warranty has a similar limitation. This means that your battery capacity will start to reduce gradually from the day it's installed, but the reduction in capacity may not be covered by the warranty. In the case of my car I've been told that a 20% capacity reduction would not be considered grounds for a warranty claim, but I've no idea what the policy is for other suppliers. I may well fit a semi-off-grid system in the future, as much for the fun of designing and building it as anything else, and as a way of providing a bit of a buffer for power cuts. I'm not kidding myself that it will make economic sense, even though a DIY system would cost a fair bit less than a ready built one. My inclination is to fit some big NiFe cells, as they have a life of at least 30 to 40 years, probably more, so at least the battery would probably recover its capital cost, perhaps even in my remaining lifetime..............

It'll be interesting to see how long it takes for the UFH component suppliers and designers to get their heads around UFH systems that operate at just a degree or two above room temperature. There seems to be a fair bit of concern about things like floor covering temperature tolerance, based on conventional UFH systems that run at higher temperatures, but even so I find it hard to understand why there's so much concern, as the sun shining on a bit of floor will often make it a great deal warmer than any UFH system. There's a bit of the kitchen floor in our old house (that has a solid concrete slab with no insulation under it) that gets too hot to walk on in bare feet in summer, just from the sun shining on it.