Jeremy Harris

As a hot return loop only needs a really low flow rate on the return side, has anyone ever tried plumbing one in 10mm? It should reduce the losses a fair bit, without compromising the performance I'd have thought.

Brilliant result, be interesting to find what the fault in the DIMM socket is; might just be a dry joint that's vibrated itself open, given that these things were controlling gen sets. Got to be worth a go at getting the socket to work, if only to get a bit more RAM in there.

Have you tried just flushing the system out with a hose? On our old house system this was easy, as both the flow and return drains were two standard drain bibs that poked out through the wall under the kitchen window, right next to our outside tap. If you have the means to do this, then it's worth a try: I flushed all the mixed inhibitor that was causing problems out of our system by just opening both drain bibs, letting the system drain right down (making sure everything was turned off) and then connecting the hose to one of the drain bib outlets with a hose clamp, and turning the outside tap on. It was pretty vigorous, and flushed clean water right around the system and back out the other drain bib. I had to turn the outside tap down a bit, as our water pressure is pretty high (around 5 bar), but even so I was able to not only flush all the old mixed inhibitor out, but also flushed a fair bit of sludge from the rads, as the water draining out turned pretty thick and black. I left it running until the water coming out was running clean, then turned off the tap, disconnected the hose, drained the system right down again and then closed the drain bibs and refilled the system with clean water and fresh inhibitor.

Welcome. Parish councils are a bit renowned for behaving like this, which is why it is always a VERY good idea to get in first and talk to as many Parish Councillors as possible before their planning meeting. I also took the trouble to make sure my wife and I were at the Parish Council meeting where our application was being discussed and that had a massive impact; I believe it almost certainly turned the result around from a recommendation for refusal to the one we got, which was no objection. The Parish Council response in itself isn't massively harmful, as long as it is not one of the Parishes that has been granted authority to produce it's own Neighbourhood Plan. From the response you've copied from them it sounds as if there is not yet a Neighbourhood Plan for your parish, as if there as they would probably have cited it. The real risk is that the Parish Council response could stir up more objections. I've seen this, where objections have appeared as soon as the Parish Newsletter had come out, with the minutes of the meeting in. If the number of objections exceeds a set figure (5 for our local authority) then that automatically triggers a change in the way the application is decided, in that it will be passed to the planning committee. Sadly, planning committee members are not planners, just councillors, so the decision will often shift away from compliance with planning law and guidance and be influenced by personal views and politics. Ideally you would have been best to try and get in first, before the Parish Council meeting, but you may still have time to go around and talk to all the immediate neighbours, face to face, explain who you are, why you want to build the house as planned and that you're not some shyster out to make a quick profit (that seems to be the thing that many suspect when they see a planning application !). I think it can be harder for neighbours to object once they've met you face to face, and understand that you're just building a home.

I wonder if the screen backlights have failed?

Not sure, but there might be. The problem is really that the vent hole is tiny, less than 1mm in diameter inside, where the silicone seal closes it off, and it only takes a really small bit of buoyant crap to get in there stop the seal seating properly. All the buoyant crap in a system should really just be from initial assembly, little bits of sealant, bits of plastic etc. When one of ours jammed, what came out when I washed it was a tiny bit of black plastic, that I couldn't identify, but assume may have been a bit of lost moulding flash from the UFH flow gauges, as they were the only bits of black plastic I could find. Once the initial crop of crud has floated up to the AAV, I would think the chances are that things should be OK from then on.

No, they don't, AFAIK. The assumption seems to be that the floor losses will even out between cold and cool weather in the heating season, which is probably fair enough, as we don't often get prolonged really cold weather. It doesn't account for the large variations, though, so in practice any suspended floor with a ventilated space underneath is always going to suffer from an increased heat loss rate in very cold weather, perhaps high enough to effect comfort levels if the floor doesn't have UFH, and enough to significantly increase heat losses if the floor does have UFH. It's hard to see a good argument for having a suspended ground floor, in performance terms. The only argument to support having one is really cost, if the site isn't level and it's cheaper to just build up the walls that support the floor to make up for the ground level variation. I looked at a suspended floor for our site, because of the slope that was left after the retaining wall went in, but concluded that the small additional cost of digging down to level the site was worth it to have the better performance of a passive slab sat on the ground.

They can be taken apart and cleaned. You can remove the one with the type of service shut off valve yours has, by unscrewing the top part quickly. The bit with the O ring on then rises up to block the hole and stop any more water coming out. It will leak a bit as you undo it, and make sure you hold the lower brass fitting secure as you quickly unscrew the top. To clean them out, the top cap can be unscrewed from the body. They are often a bit tight to undo, but the seal is an O ring in the top. You can then lift the float and lever arrangement out and wash out any muck that is holding the thing open (it doesn't take much). When it's all clean reassemble it and refit it by very quickly screwing it back into the brass fitting. Putting an old towel around it when taking it on and off is usually enough to absorb the leakage. These things do have a bit of a reputation for blocking like this, as any tiny bit of buoyant crud can find its way to the tiny air hole where the valve is, and jam it. There is a far more expensive type that pretty much never gets blocked, and that's the Spirovent. Personally, I'm of the view that the best way to use ordinary AAVs like this is to leave the caps open whilst you initially set the system up, to allow any air to bleed out, then shut the caps down and treat them like manual air vents, unless you have a specific need to continuously vent a system that accumulates air for some reason. You could buy another one the same as you have, and just swap them over, cleaning the blocked one in slow time and keeping it as a spare, as they are not that expensive. Heating systems in general shouldn't need automatic vents, as there should be no reason for gases to build up, although I know from experience that this can happen, as it happened to our old central heating system, and was eventually put down to there being two different makes of inhibitor in it, as when drained the water came out all frothy, full of gas and milky-looking. Washing it through with clean water for an hour or so, then refilling with Fernox, fixed the problem completely, and since then I only ever put the same type of Fernox in it , and the problem hasn't recurred. We have a Spirovent fitted on our main water feed, as our water is heavily aerated as a part of the treatment process, so there is always a lot of dissolved air that if I don't remove ends up as small air pockets that then make the taps spit a bit. The version of the Spirovent I have is one that includes a stainless microbubble collector, so it takes pretty much all the air out of the water before it gets to the rest of the house. I doubt that you need anything like this on your system, and would suggest that using your AAV as a manual vent, closing the cap and just periodically opening it to see it there is any air collected in the cup, is probably good enough.

Even if you can't get them working as PCs, there have to be some useful parts there that are worth salvaging. If the screens can be made to work, then they alone would be very good for anyone into home CNC, that's looking for a robust monitor. The same goes with a lot of the other parts, I suspect, as they will be industrial quality components, and presumably a bit better than the typical consumer-level stuff. I acquired a Dell keyboard and monitor via our IT procurement people before I retired, and the quality is very much better than consumer level stuff. The keyboard is now around 7 years old, yet still looks and works like new, more than can be said for most of the tat that comes supplied with a new PC nowadays. The monitor doesn't get much use, as I bought a much larger one a few years ago, but is the same sort of robust quality as the keyboard.

It's worse with suspended floors, for sure, especially in really cold weather, just because the air under the floor will be close to the outside air temperature. At least with a solid floor the lowest temperature under the floor is unlikely to drop below about 6 deg C, and will most probably be around 7 or 8 deg C. That makes a substantial difference to the heat loss rate, no matter what level of floor insulation you have, just because the temperature differential is so much greater for a suspended floor. Although our old house has uninsulated solid floors, at least they don't get any colder in cold weather, they are always just slightly chilly. We had an outside air temperature of around -3 deg C the night before last, and had we had a suspended floor that would have been around the temperature underneath it, rather than the 8 deg C it normally is. An extra 11 deg of temperature differential will give a pretty substantial increase in heat loss. If you had a floor with a U value of, say, 0.5 W/m.K, then a solid floor would lose around 6.5 W/m2, whilst a suspended floor with air at -3 deg C flowing under it, would lose around 12 W/m2, a substantial difference.

602

Best to use the efficiency that's given in the SAP database for the MVHR unit, that should be pretty close to reality.

'Tis here: http://www.mayfly.eu/wp-content/uploads/2017/01/Fabric-and-ventilation-heat-loss-calculator-Master.xls Lots of people here have used it.

One other thing to look at is whether the wifi is smart enough to choose the least congested channel. I have an old D-Link router still running at the old house, and it is exceptionally bad at choosing the best channel within the 2.4 GHz band. A quick look at what channels any reasonably strong signals from other nearby users are on, then going into the router and manually selecting a different channel, can help. There are some reasonably easy to use bits of free software that will use the device's wifi receiver to give an indication of the amplitude of all the signals it can identify, like https://www.acrylicwifi.com/en/wlan-software/wlan-scanner-acrylic-wifi-free/ but you need to take their signal strength readings with a bit of a pinch of salt, as the RSSI output from many wifi devices isn't well calibrated, it's really just useful for making relative comparisons between signals.

There's loads of heat released as a consequence of condensation in the heat exchanger, so with warm, moist air being drawn out, and the moisture condensing in the heat exchanger and giving up its heat to the incoming fresh air, you can get some pretty high apparent heat exchange efficiencies, especially if the outside air is dry, as it will be in cold weather.

Worth noting that most of the water in concrete never, ever comes out of it, it gets used in the complex chemical reactions that causes Portland cement to set. The reactions are complex and poorly understood, even now, but a fair bit of water goes into the intermediary compound Ca(OH)2, that eventually (after literally years of absorption of CO2) becomes the somewhat harder CaCO3. This is one of the reasons that concrete continues to age harden over the first few decades after it has set. It's important that concrete not be encouraged to "dry out" for several months after it has been laid, as it continues to harden by the initial curing reaction (the one that absorbs water as Ca(OH)2 is formed) for several months, at least three months, often much longer if the temperature is low. If partially cured concrete (less than around 3 months old) is forcibly dried out, then the initial cure will stop, and there will be deep regions that remain not fully cured. Generally this deep moisture never presents a significant problem. It will end up being incorporated into the final matrix as one of the intermediary compounds, and won't present a problem by coming to the surface unless it is forced to by some means.

You can take a static reading anywhere, just make sure no one has an outlet open when you do. The static pressure will be more or less equal everywhere if the pipe run from the main is fairly level, as I suspect it is knowing your location.

Solar and incidental gains can make up most of the heating requirement, especially on clear and cold days, we've found. Our house (same construction as yours, but in a more sheltered location) was boarded out and plastered in January/February, when it was pretty cold. There was no heating, and the MVHR wasn't commissioned or running, but the heat from two or three people, plus a couple of 400W halogen worklights soon made the temperature indoors unbearably hot. I had to go and buy some low energy worklights, just to reduce the heat input.

Not at all, for some reason midges only start to appear further North. I used to have to travel up to Loch Goil, around 2 1/2 hours North of Portpatrick, a fair bit, and midges were certainly an issue there. There seems to be a line, roughly from Glasgow to Edinburgh, that defines the Southern boundary of midge territory, I think. Portpatrick is pretty far South, about the same latitude as Newcastle and only about 20 miles from Belfast, plus it's on a coastal peninsula, so strongly affected by the surrounding sea, which keeps the area warmer than you'd expect. There's a botanical garden just down the coast at Port Logan, and look at what's growing there will give an idea of the local climate: http://www.rbge.org.uk/the-gardens/logan

We moved North to Dumfries and Galloway. Very little traffic (except on the A75 when the ferry disgorged a load of cars and lorries at Stranraer) and I don't think we ever had a frost in the five years we lived there. There were palm trees growing all around the village it was that mild. We did have about half an inch of snow one Christmas Day, which fell whilst we were driving to a local hotel for lunch, but it had melted by the time we drove home later. That was the only time I ever saw snow there. The climate was very like that in the South West of England, mild, wet and a bit windy around the autumn and spring equinoxes. Summers were often very sunny, but not too hot, because of the sea breeze. When we moved from there down to West Sussex it was November and the first thing I noticed was how cold it was, far, far colder than Portpatrick.

Depends. 32mm MDPE will drop 1 bar over 110m at a flow rate of 40 l/m (approximately 4 normal showers running at the same time). You need around 1.5 to 2 bar at the house as a rule of thumb. So, if you have around 3 bar at the water main end of the pipe, 32mm should be fine. If it were me, I'd get a pressure gauge and have a look at what you've got at the moment. You don't need to measure at the main, if you close all the outlets at the house end and put a pressure gauge on that end it will give you the static pressure. If that's high, say 4 to 5 bar, then you can be confident that 32mm will be fine, if it's a fair bit lower, you may need to rethink.

The ARUP calculator does a reasonable job: https://www.concretecentre.com/Publications-Software/Publications/Dynamic-Thermal-Properties-Calculator.aspx

Doesn't make any real difference, other than the question as to whether the boiler can actually modulate down to the lower power needed at the lower flow temperature without tripping the anti-short cycle timer, by shutting down. Generally, boilers of all types (and heat pumps) work more efficiently and tend to be more reliable, if they are not short cycled. Starts and stops have a significant impact on both efficiency and reliability. One way around this if you only need a low flow temperature for UFH is to run the boiler into a buffer tank at a reasonable temperature, say 50 to 60 deg C, then let the UFH draw off water from this, via it's thermostatic mixer, as required. The boiler can then run for a longer time, both running the UFH directly and slowly recharging the buffer tank, then shut down and stay off for a fairly long time whilst the UFH draws the heat it needs from the buffer tank.

The return temperature is directly linked, in a non-linear way, to the flow temperature. The flow temperature determines the heat output of radiators, and these will cool the water as the give out that heat by an amount that depends on their area, airflow around them, the room temperature, as well as the flow temperature. If the system has radiators with TRVs, then the return temperature will also vary depending on how many radiators are actually delivering heat, and at what rate. As the flow temperature is reduced, the return temperature will also reduce, with the difference between the two being higher with a high flow temperature than with a low flow temperature. The lower the return temperature, the more efficient a condensing boiler will be, and it carries on getting more efficient as the return temperature drops, although the efficiency gain with reducing return temperature falls off a bit as the return drops below about 40 deg C, as by then the boiler will be near enough 100% condensing, and so there's little gain below that.

Depends on how even the temperatures are around you. One of the most noticeable things with our new house is that all the surfaces, walls, ceilings, windows, floor etc are at near enough the same temperature. The variation is less than 1 deg C, even on a cold day. The effect of this is to make you feel more comfortable, and I have a theory that this is to do with the way the body senses thermal comfort. Air temperature seems only a part of the overall feeling of comfort, it seems that we are quite sensitive to directional heat loss, mainly by radiation, but also by conduction. I can't prove this, but empirically, standing inside in front of a window on a cold day feels a great deal more comfortable at the new house than at the old house, even though the old house probably has a warmer room temperature. I think this is down to our bodies being pretty good at detecting directional radiative heat loss, and with 3G windows, with two panes with a low emissivity inward facing coating, the radiative heat loss through the glazing is very much lower than from the 12 year old double glazing at the old house. The same goes for sensing conductive heat loss. The solid concrete floor of our old house has no insulation, and if you stand around for a while, or sit with your feet on the floor, it doesn't take long for your feet to feel cold. I tested this out with a 50mm thick offcut of PIR foam, that I put on the floor under my desk, to rest my feet on. It makes a very significant difference to how my feet feel!