Jeremy Harris

I think you'd have to try it and see, TBH. I have an energy/power meter on the ASHP supply, so I could measure the energy/power going in and estimate what was coming out, and after some experiments with different settings I concluded that, for our set up, there was no benefit in reducing the ASHP flow temperature down to 30°C. I should qualify that by saying that I only tested the different settings over a modest range of weather conditions, and didn't try turning the flow temperature down in very cold weather, to see if there was any performance improvement. As we don't get many days a year here when it's sub-zero, I'm not really that bothered if it is a bit less efficient under those conditions, particularly as I can't see any obvious dip in performance from the energy use data; that seems to track the outside temperature reasonably well, albeit with a bit of lag.

I run it at 40°C because the DHW pre-heat is useful (cheaper than using more grid energy to charge the Sunamp) and because there seems to be no noticeable performance difference between having the ASHP running at 30°C and 40°C. At 30°C the ASHP would tend to cycle on and off, as the heat output was below its lowest modulation capability, whereas at 40°C it stays on. There seems to be a very slight advantage in having it run for longer periods, as when it starts up it ramps to full output over a period of around 30s to 1m, then gradually modulates down to a speed where it can maintain the set flow temperature.

I agree, and that creates a problem if you have a house that responds slowly, as you really need the flow temperature to predict the required temperature in a few hours time. It's one reason I binned the heat curve on our ASHP and just set a fixed temperature of 40°C. It so happens that the ASHP works very efficiently at that flow temperature too.

I actually wanted a manual door, but couldn't find anyone who sold one in a domestic paint/powder coat finish, plus the industrial manual doors I did find cost more than an electric one. The controls on mine now are just a rocker switch that has to be held down to make the door go up or down, and that's fine, much better than the overly complex pile of crap that Seceuroglide fitted to the door.

Worth bearing in mind Pascal's Law...

The PITA is that it's hard to get hold of the DNO spec concentric cable. If you want to try and find a supplier, then it's usually 35mm² concentric the DNOs use I believe. The cable would have to meet the DNO spec for them to be happy with connecting it up, though, and they would probably want a paper trail to ensure it conformed to their spec.

Thanks, it looks like they have reacted to customer complaints. Having to fork out around £6 for two 3.6V AA size lithium cells every six to nine months, plus the fiddle of dismantling the (fragile) sensor housing to get at them, was something that managed to really hack me off. When I contacted them about the problem, saying that the screws were now so loose that they were falling out, all they suggested was replacing the whole wireless sensor unit, at a really silly price. It was much cheaper to buy a complete new (non-Seceuroglide) control box than it was to just replace the Seceuroglide wireless sensor.

PHPP is very good, but it can be a bit daunting initially. If you just want to get a rough (within about 10%) idea to start with, as to how changing things like wall, floor, roof, door and window U values affect things, or how much impact MVHR makes, then I wrote a simple heat loss spreadsheet to try and help answer these early "what if?" questions. The file is an ordinary Excel file, but the forum software doesn't like files with .xls extensions, so download this, then rename it to change the .txt to .xls (I can promise it's safe, and has no macros etc): Heat loss calculator - Master.txt This simple heat loss calculator takes no account of solar or incidental heat gain, exposure level of outside surfaces, etc, it simply calculates the heat loss for any particular fabric standard and temperature differential. We, and others here, have found it does a reasonably good job or predicting performance though, and although definitely not a substitute for PHPP, it is a bit easier to use, so ideal when you are just looking to get a feel for what sort of performance you are likely to get for any particular fabric build standard. If you want to have a look at the effect of floor insulation specifically, with underfloor heating, then I also put this spreadsheet together (same as above, rename the extension after saving the file): Floor heat loss and UFH calculator.txt

There are certainly LEDs available that emit in the UB-B/UV-C wavelength. Whether the intensity is enough to promote vitamin D production by the skin is debatable, though. My own view is that it's doubtful, as the intensity of even a large artificial light isn't likely to compare to that we get from sunlight exposure. If vitamin D deficiency is a concern in winter, then it would probably be a lot more effective to just take a vitamin D supplement. There's plenty of evidence that having artificial light in winter that has close to the full spectrum of sunlight does have an impact on our circadian rhythm. Whether it's advantageous to try to maintain a summer circadian rhythm in winter is debatable, but there is weak evidence that some people can be more susceptible to shorter daylight hours, and suffer mild depression as a consequence (what's often called SAD, seasonal affective disorder). Choosing lights that have as close to the full sunlight spectrum as possible may help, and you can get LED lights with a high CRI (colour rendering index) that have a pretty wide spectral range. I've no direct experience of using these, and they tend to be quite expensive, but my guess, just from looking at the spectral data, is that they may help those with symptoms of SAD. I doubt they do much in the way of promoting the skin to produce vitamin D though.

The main active ingredient is phosphoric acid. It's very unlikely to do any harm to the treatment plant, mainly as the concentration would be pretty low. Phosphoric acid is also the stuff used to convert ferric oxide into ferric phosphate, the black anti-corrosion coating seen on things like guns.

Nice to see it's a sensible design with a wired safety switch at the bottom. I made a mistake in buying a Seceuroglide door, that has a wireless safety edge at the bottom. What they don't tell you is that the wireless safety edge eats very expensive lithium batteries, plus you have to undo half a dozen self-tapping screws, screwed into flimsy plastic, in order to replace these batteries. After three battery changes I found the screws were no longer secure, and started falling out as the door operated. I enquired about a new safety edge transmitter and it's a ludicrous price, so I removed the Seceuroglide control system completely, discovered that the roller motor and limit switches were pretty standard and would work with any controller, so added a much cheaper controller and wired safety switch. This has no batteries and just works reliably.

We've also built to the PH standard, but opted not to go for certification, just because it was an additional cost that we didn't feel was going to add value. We chose a timber frame package that included the passive slab foundation system and which was guaranteed to meet the PH airtightness spec, really to save a bit of hassle and to reduce the risk of one contractor blaming another if there was a problem. I'd agree with the above, pretty much any build method could meet the PH standard, but some will need more attention to detail, specifically with regard to airtightness. I believe that one reason there are a few PH timber frame options available is that it's a bit easier to get timber frame construction airtight than something like block and brick, but with patience block and brick could be just as good. As yet it doesn't seem as if any of the package build companies are offering ICF as an option to meet PH spec, not sure why, as ICF should be as easy to make airtight as timber frame, at least for the EPS ICF systems.

Ours is a 2000 x 900, 40mm deep. I laid 9mm marine ply, glued and screwed to the floor around it. then tiled the floor with 12mm thick travertine, and the result is that the shower tray is about level with a bath mat laid by the opening. There would be no problem at all in getting a wheelchair into it.

I just used Aquacell drainage crates (see here: http://aquacell.wavin.co.uk/ ). I used 20 of the blue Aquacell Core crates, tied together with the Aquacell connector tubes and clips into a big rectangular block, with the block being wrapped in terram and buried in a big hole under the drive. Runs of 110mm soil pipe connect from the top of this surge tank to the house and garage drain pipes. The top of the crates was covered with compacted Type 3, so that water run-off from the drive can permeate down into them. The only snag with this system is the cost of the crates, they are not cheap. I was lucky, in that I found a load for sale on eBay, and it's worth keeping an eye on there, as when I was looking I found quite a few surplus crates being offered for sale. Mine came from a ground works chap who had them "left over" from a motorway job (they use these for motorway soakaways). Funny thing is the the seller's name was Dell, and he delivered them to us, for cash...

Can you get away with a surge storage system, with a slow infiltration rate? We have one under our drive, less than 3m from the house, that can hold a rainwater surge of nearly 4000 litres, which it then drains away via a small area of permeable soil. Because I had to fit it under the drive (only place it could go, plus we needed a SuDS compliant solution for the permeable drive) I had to use the reinforced Aquacell crates, but if you have space under an area of the garden then the lighter weight crates would be OK. They aren't cheap, but I got lucky and found some surplus ones for sale on eBay at around 1/10 of the cost of buying from my local BM.

I have a portable ozone generator that I used to use a bit at the old house to get rid of lingering cooking smells. It works very well, just plug it in, close the door and come back half an hour later and there's no trace of any smells (kills all the bugs in a room too...). I've not felt the need to use it in the new house, mainly as the MVHR is pretty effective at getting rid of any lingering cooking smells. We do still have a small ozone generator that sits inside the fridge, and activates periodically to remove smells. Seems to work well, especially if there are any pongy cheeses in the fridge.

Be aware that UV isn't a true sterilisation method, it acts as a disinfection system but even then it only works reasonably well if the water supply to the UV unit has been filtered to < 5µ. If the supply to the UV unit isn't filtered down to this level then UV treatment won't do much, as bugs will be shielded from UV by the fine particles that haven't been filtered out. A 5µ filter will need pre-filters to take out the larger stuff, or else you'll be replacing filters every couple of weeks. UV treatment also has an annual running cost of around £80 to £100, roughly 50% of that is electricity and 50% the cost of UV tube replacement. To that you need to add the cost of the filtration system expendables, which depends a great deal on how clear the water coming in is. Might be worth considering a backwashable filter vessel 1/3rd filled with Turbidex, as that will filter down to close to 5µ on it's own, and can be backwashed to clean the media, rather than having to replace cartridge filters. Backwashing can be run automatically at night (our main filtration system does this, a backwash every 4 days, at around 02:00). I'd try and avoid over-complicating any rainwater harvesting system if you can, as even a basic system will require a bit of regular looking after and the simpler the system the better, IMHO. If you can restrict rainwater use to non-critical uses, like toilet flushing (and NOT running the washing machine, they don't normally get hot enough to kill any bugs), then you can get away without much in the way of filtering or disinfection. My experience is that any form of water treatment requires maintenance and incurs a significant running cost.

That's exactly what I did with Wessex Water, before we agreed to purchase our plot. Not only did they email me the map showing local services but they also sent a chap out to measure up and provide the info they needed to give a quote. There was no charge for this, neither was there a charge from SSE or Openreach for doing the same for their services.

I found that the utility companies would do this for free, on request. For example, I emailed Wessex Water and they replied with a PDF map attached showing their water and sewerage network (as much of it they knew about) the same day. My guess is this company is just charging people for info that they could have got directly from the utility companies, had they asked. I don't know whether or not it's any more accurate; my guess would be that the definitive records are held by the utility companies themselves (not that that means they are accurate, as we discovered).

I put together a spreadsheet to calculate UFH heat output that I've posted here a few times: Floor heat loss and UFH calculator.txt (save the file then edit the suffix to .xls - the forum software doesn't allow spreadsheet files as attachments)

I seem to remember having to specify 2400 x 1200, rather than 8 x 4, as 8 x 4 = 2440 x 1220, and we needed 2400 x 1200 to match the 400mm spacing of the counter battens and studs and the 2400 room height.

Yes, it was indeed in XX475! The red car is my road-going single seater I built when I was up at West Freugh in the mid-1990s

I've experience of reduced partial pressure of oxygen; had to endure a hyperbaric chamber session every two years for around 20 years. Up to about 10,000 to 12,000ft (reduction in available oxygen from about 21% to around 12% to 13%) there are no perceptible physiological symptoms for the vast majority of people. Above about 12,000ft symptoms of hypoxia start to become apparent, but hypoxia is insidious, in that you are often completely unaware that you are becoming hypoxic. The idea of making aircrew do a chamber run every two years was precisely because the symptoms of hypoxia are so difficult to spot. By sticking you in a chamber with a doctor, then taking you up to 25,000ft, you get a chance (a slim one, in my experience) of being able to detect your own set of symptoms that might, possibly, allow you to recognise that you are hypoxic. I should add that at 25,000ft with no oxygen most people only remain conscious for five minutes or so, so it was a slightly extreme way of teaching a vital safety lesson. To highlight just how insidious hypoxia can be, this is a tale of the only time in a few decades of flying that I've ever been hypoxic. Two of us were flying from West Freugh up to Inverness. I was in the right hand seat, pilot flying was in the left seat. I did all the flip card checks, and our taxy checks were interrupted several times by a minor airfield emergency (nothing to do with us, but there was a lot of radio chatter). We lined up, took off, completed the post-take off checks and set the autopilot to climb on a set heading. We'd been cleared to FL22 (~22,000ft). About 3 or 4 minutes into the climb I noticed my ears pop more abruptly than usual and made a remark to my colleague, who confirmed his had as well. We just assumed that the cockpit pressurisation was being a bit clunky (not that unusual). We sat back for another few minutes, when I spotted the altimeter coming up to our assigned cruise height and mentioned it to my colleague. He didn't reply, so I gave him a nudge, and found he was asleep. He didn't wake up, so I wound the height bug down to level us out, but found that I was really struggling to do something this simple. Not being able to wake my colleague up didn't bother me at all. I eventually noticed that my vision was fading to black and white, remembered having experienced this in the chamber and thought to look down between the seats at the cabin altitude gauge. It was showing 22,000ft, when it should have been around 8,000ft. There was no way I could fly the aeroplane, but I did manage to wind the height bug right down to a few thousand feet, which caused the autopilot to put the aircraft into a steady descent. I'm not sure if I remained conscious or not, but remember making a pan call much later, telling Scottish Mil that we were doing an emergency descent, so they could clear any conflicting traffic out of the way. My colleague came to just as I was making the radio call, and was as confused as hell. We sorted things out, cancelled the sortie to Inverness and headed back to West Freugh. We both regained full consciousness pretty quickly and spotted the cause of our problem before we landed. During the interrupted taxy checks we'd both somehow missed the pressurisation dump valve check and cross-check, and left it wide open. There was no way the cockpit pressurisation could have worked, as with the valve open at the rear of the aircraft pressurisation air would have been blowing out as fast as the engines could pump it in. In the inevitable stack of paperwork we had to complete after we'd landed on, we both noted that neither of us had thought to don our emergency oxygen masks, despite them being stowed at the side of our seats. Looking back, we were both seriously compromised by hypoxia, and it was pure luck that we came out of it OK. My colleague was about 10 years older than me, with over 30 years flying experience in fast jets, yet this didn't help him spot that he was losing consciousness. It was pure luck that I spotted the loss of colour vision. If I hadn't been concentrating really hard on the flight director display I might well have never noticed that I was on the verge of passing out. We could very easily have been yet another "pilotless aircraft flying on until the fuel runs out" accidents. I think I worked out afterwards that we'd have been over half way to Greenland before we'd have crashed into the sea. Whether we'd still have been alive when that happened is anyone's guess; I think we probably could have been.

I wanted to fit Japanese-style bidet/toilets, but SWMBO vetoed the idea. I think they are great, with the one exception that I wasn't much taken with the tunes they play (apparently the idea is to cover up any embarrassing noises). They are fitted to hotels in Japan, so I would guess that they are reliable. They are expensive to buy here, though, and finding a decent one that has English instructions on the controls can be a challenge; when I last looked all the "cheaper" ones seemed to be imported products intended for the Japanese domestic market, with just Kanji on the controls (interesting to see that the Kanji for the two main washing functions translates as "bottom" and "front bottom"...). A reasonable compromise is to fit a hand-held shattaf shower unit by the toilet. Does much the same job as the washing elements of a Japanese toilet, albeit without the automation or the warm air drier.

One thing we got wrong was the gutters, that I need to get around to replacing this spring. Our roof pitch is 45° and the combination of that and a large area of in-roof PV panels means that heavy rain seems to come off the roof in torrents, which then overwhelms the standard half round gutters and spills over the edges. I plan to replace the standard gutters with the deeper/wider high flow rate one, just to stop them from spilling over in heavy rain.