Jeremy Harris

I'm peripherally involved with a case where someone has installed a potentially hazardous, very bright, outside floodlight. It's motion activated, but comes on every time a car drives along the lane, and shines directly into the eyes of oncoming drivers. The owner's refused to do anything about it voluntarily (says he needs it to see the entrance to his drive) and the local highways people are looking into whether there's any legislation that can force it to be relocated. Doesn't look to be something that;s either easy or straightforward, as far as I can tell.

Our insulated slab took 4 days to lay, start to finish. Guys turned up very early Monday morning, were off site late on Thursday night, having levelled the area, laid the insulation and DPM down, tied in all the steel reinforcement, fitted all the UFH pipes, service pipes, ducts etc, poured the concrete on the Thursday morning and finished power floating it dead smooth and level (ready to lay flooring on directly) late on the Thursday evening. That was an 85m² slab for a 130m² 1 1/2 storey house.

Our's much like @ProDave,s, a single vertical soil pipe that runs behind my study wall and drops into a rest bend under the slab. It's inaudible. All I did with ours was box it in with 12mm OSB where it comes down partly in the downstairs WC, with the box being filled with packed in rockwool leftovers from the wall and ceiling acoustic insulation. Plasterboard was bonded on to the OSB with low expansion foam. At a guess there's probably only about 50mm of insulation space around the pipe, maybe less, but that seems enough to silence it.

This looks to be a combination of conventional mini screw piles (like these, for example: https://www.minipilingsystems.co.uk/screw-piles/ http://www.groundsun.co.uk/content/screw-pile-foundations/ ) with a ring beam. Might be useful on difficult ground, or an area where sub-surface stuff needs to be protected, but probably a bit costly when compared to other solutions. If piles are needed, then it may be worth considering, but otherwise I suspect that other foundation solutions may be more cost effective.

I have a pressure reducing valve that connects the 1/2" BSP tap connection to the smaller Claber hose: https://www.claber.com/uk/cod/91040/Block-system-Rainjet/Pressure-reducer . This makes it easier to regulate the drip valves, I think, and came with the starter kit I bought.

85% is fine for the MVHR, it's a pretty typical figure, perhaps slightly on the low side, but that's OK for estimating heat loss. 7.5 kW seems close to what I'd expect for a house the size of yours, built to typical building regs insulation and airtightness levels (ours is a great deal better than building regs requirements, hence the much lower heat loss). As others have said, 16 kW seems way more than expected for a house of your size. ASHPs come in set sizes, so I'd be inclined to go for one the next size up from the 7.5 kW you've calculated, say 9 kW, to give a bit of a margin (although the spreadsheet does really give the worst case when it's -10°C outside and the house is empty, with nothing on except the heating). That should be fine, even allowing for the slightly higher heat loss from your windy location (@Stones has observed that wind makes a significant contribution to heat loss; he's up in Orkney).

Use the overall dimensions of the doors and windows, together with their U value (Uw in the case of windows and glazed doors). Use the average Uw value for all the windows if they vary a bit from one window to another. You should have all the information needed on your design SAP input worksheet. The output figure is the total heat loss from the house, which will be the very worst case heating requirement, as the spreadsheet doesn't account for solar gain, or incidental heat gains from appliances, lights, the hot water tank waste heat, occupants, pets etc. In practice every occupant contributes around 80 to 100 W of heat, the hot water tank roughly the same, and appliances may well add another 200 W to 300 W of heat gain (pretty much all the power going into the house ends up as heat). You should be OK sizing the ASHP on the basis of the heat loss from this spreadsheet. For example, for our 130m² the worst case heat loss, when it's -10°C outside, is about 1.6 kW. In practice we've found that we never need more than about 1 kW of heating in very cold weather, and most of the time in winter we only need around 500 to 600 W of heating. I fitted a 6 kW Glowworm ASHP, but it's massively oversized for the house (it happened to be cheap at the time, £1.7k delivered). Our house would be fine with a very much smaller ASHP, but these aren't that common, about 4 kW seems to be the smallest readily available.

I can throw a practical data point into this mix. A few weeks ago I installed a (recirculating) air con unit in our bedroom. It tries to maintain 20°C at its air intake, using its thermostatic control. We leave the bedroom door open all day (it opens to a landing above a 6m high, 5m long, 2m wide entrance hall in the centre of the house). The MVHR temperature sensing and control is on the landing, the floor heating/cooling thermostats are on the ground floor in the hall. In practice the air con holds the bedroom at close to 20°C all the time, the landing is very slightly warmer most of the time (perhaps 21°C) and the same with the ground floor. Both the floor cooling and the MVHR cooling tend to come on a bit later as a consequence of the effect of the air con cooling, but this seems to work very well indeed, as we end up with the ground floor rooms around 1°C to 2°C warmer than the bedroom, which we find about right.

In general terms, what @joth says is right, but I'd add that of all the possible ways to gain light into a room, bifolds are almost certainly the least thermally efficient. The seals will gradually lose their effectiveness with time, just due to the geometry and the very light sealing forces that are available to try to maintain compression on them. For a house that stays cool, even in summer, adding glass will make it colder in winter. Solar gain in the coldest months of the year is negligible, and I strongly suspect that the reason this room is colder than others has everything to do with factors other than solar gain. Does it have more than one external wall, for example? Corner rooms lose more heat than those in the centre of the house, as do single storey rooms, or worse still, single storey rooms with three external walls.

As @Ferdinand says. it might be worth trying to find out if there is a "Dark Skies" initiative for your area. Our AONB here is trying to gain "Dark Skies" accreditation for our area and consequently there are a fair few restrictions imposed on exterior lighting, street lighting etc. Even if there's no such initiative where you are, there may possibly be a local planning policy covering light pollution that might be of use.

We ran a duct underground for the power, at the same time as we put the treatment plant in, which was during the ground works, before the house build itself was started. The cable's a run of SWA that connects to a watertight distribution box near the treatment plant, with the cables to the air pump, water pump and alarm system made off from there.

Best thing I've ever bought was a set of Peltor ear defenders with a built-in FM radio. Means I can listen to the radio without annoying anyone else. It also means that I can put them on to listen to the omnibus edition of The Archers on Sunday morning without being disturbed...

As far as ventilation goes then it's fine, but it might be hard to comply with Part B for some habitable rooms (not a bathroom) without some opening windows (needed for escape from fire usually).

You really need to try and work out your worst case heating requirement, assess how much hot water you need, then work from there. You can get a pretty good estimate of the heating requirement using the spreadsheet I wrote a few years ago. Just put in your external wall, roof and floor areas, window and door areas, and the associated U values, together with your estimated airtightness level and MVHR efficiency. The spreadsheet will give close to a worst case heating requirement for an empty house, with no incidental heat gains, solar gain etc. Heat loss calculator - Master.xls Hot water capacity depends on how many are in the house, but for a house that size I think 300 litres is probably about right, I'm not sure that it would be sensible to go down to 250 litres or less, as an ASHP will be a bit slower than a boiler to reheat the tank, and the stored hot water temperature will be a bit lower, probably no higher than 55°C, so more hot water will be used when mixing down for showers or a bath than would be the case for a boiler heated tank, that may well be around 65°C or so. I'd be surprised if you need more than about 10 kW of heating capacity, very worst case, in extremely cold weather, TBH.

I'd never use a jubilee clip for something that might fall off down an inaccessible hole, personally. Easy enough to use an "O" clip, more secure than a jubilee clip and a fair bit smaller. You could probably get away with having the non-return valve part way along the suction hose, depending on how well the pump stays primed. I'd be inclined to use a strainer, if only because you can't be sure that something may not have gone down the hole and died, only to then get partially sucked into the intake pipe.

Priming by pouring water down the outlet works OK if the pump has a foot valve on the end of the intake. Easy enough to fit one, just needs a one-way valve on the intake strainer. You can then fill the intake pipe up and prime the pump by pouring water down the outlet.

Yes. The limiting factor is air pressure, which limits the theoretical maximum head that a pump can suck to about 30ft, although in practice few pumps manage better than about half this on the suction side. Priming is the only real issue, as a non-positive displacement pump (which many are) won't suck at all unless the suction pipe is full of water.

A small pressure drop when testing overnight, as things cool down, is normal. Water is virtually incompressible, so with the system full of water, with no expansion space, then the pressure will go up and down a great deal with temperature. Even a tiny amount of expansion as the water warms up will increase the pressure a fair bit, and the same applies as the water cools down and the volume of water decreases very slightly.

I agree. We have stairs with a ~200mm rise and ~260mm going and, with hindsight, I wish we'd given up a little bit of hall space and made the stairs more generous. They are just a bit steeper than I'd like, not really noticeable going up, but in a single flight going down I feel the need to grip the handrail.

I've taken one of these apart to see what's in it, and it's just a bit of LED strip wrapped around the edge of a diffuser. There's nothing else inside the light itself, so my guess is that the most likely failure mode might be the driver. I had problems with RF interference from the drivers on the lights we bought, so I binned all the drivers and fed the lights with low voltage DC (12 V for the 3 W lights, 24 V for the 6 W lights) using the same value of current limiting resistor at each light (6R8 ohms, 1 W). This very slightly reduces the efficiency (there's a loss of ~0.6 W in the resistor, versus a loss of ~0.5 W in the old driver, not enough of a difference to lose any sleep over), but means that I can use a single supply to run lots of lights, and also means that replacing that supply in future should be easy. I also ordered lots of spares, as these lights were pretty cheap, plus I wasn't sure whether to use warm white or cool white, so I have a box with over a dozen assorted spares. I put these lights in around 4 years ago now, and they are all still working fine. They don't noticeably warm up in use, which bodes well for them having a long life, as heat is the enemy of LEDs, and one reason why some LEDs that have been adapted to fit things like halogen fittings seem to have a fairly high failure rate (halogens like to run hot, so halogen fittings aren't designed to keep lamps cool). The connection between the light and the driver is a standard low voltage DC power plug and socket (a 5.5mm x 2.1mm one) so it's easy to swap a light over, should one fail.

I can't see why it wouldn't work just fine plumbed in to an extract fan. Just a matter of making up some sort of connection to the inlet side of the fan.

Like wise we have a mix of very similar 3 W and 6 W LED edge-lit panels here, been fine so far. They all seem to draw ~ 250 mA to 300 mA, from a constant current source, with the voltage at the 3 W one being around 11 V, and the voltage at the 6 W ones being around 22 V. Some of these panels are supplied with constant current drivers that can be a bit noisy, in terms of RF interference, some come with drivers that seem fine. We have some warm white ones that are fine in the dining area, and cool white ones in the kitchen. The cool white ones seem marginally brighter, and give a good light for cooking.

Just stick a small computer fan on the pipe and see what happens. My guess is that it will work fine, as I don't think that the airflow rate on ours is very high at all. I think the secret is that there's only a small volume to ventilate, and only a relatively small volume of "smelly stuff" to remove. A couple of air changes of the pan air volume might be enough to get rid of 90% of the odour.

It's surprisingly reassuring to leave the bathroom after a particularly malodorous event, secure in the knowledge that you've not left anything behind that might cause offence to the next user. Not just me that's feels this way about it either, it was commented on earlier today, hence the reason for deciding it was time for an update.

You're probably right, but when the ASHP starts regularly running defrost cycles it does really slow down, at least ours does. It switches to cooling mode in defrost, so draws heat out of the tank. For some reason best known to whoever wrote the code in our unit, the defrost time sequence seems to be the same for any condition. It doesn't seem to run shorter defrost cycles when the conditions are marginal for ice formation, so can spend 10 minutes, maybe two or three times an hour, defrosting. I haven't measured the impact this has on COP, mainly because we don't use the ASHP for hot water, so I only bothered playing around with settings relevant to heating. I suspect that @joth may be right, though, in that the COP might drop below unity at times. The other issue is that some ASHPs seem to have a built-in resistance heater that they switch on when required to deliver high temperatures, and some don't seem to have the ability to easily disable this. This makes me wonder if those manufacturers have realised the potential impact of running defrost cycles, if the unit is asked to deliver fairly hot water, and concluded that it's better to boost with resistance heating.