Jeremy Harris

This is what I did, I put the intake on the North wall and the exhaust on the East wall. I'm now in the process of moving the intake to the East wall, as the imbalance caused by any slight breeze is audible at the MVHR unit, as it forces the fans to speed up/slow down. My only option for a fix is to run some external ducting down and across the North wall, to position the intake facing East by a lot lower (probably around 3m away) from the exhaust. There is a secondary advantage to doing this, in that by lowering the intake I can fit an easily accessible pre-filter box, that I hope will reduce the amount of crud that ends up at the intake filter. I have some left over larch cladding, so intend to hide the extra external ducting in a larch box. It's at the back of the house, in the alley between the house and the tall retaining wall behind, so won;t be visible from any normal external view.

These are really a fair bit too close together, IMHO, especially in what looks to be a sheltered location. I think I'd definitely want to shift one a fair bit further away if it were me. Ours are around 2.5m apart, and I'm in the process of adding an extension to the intake to increase the separation distance even more. Also, if fitting one above the other, then there can be an even greater risk of cross flow from intake to exhaust. The exhaust air will usually be warmer than the intake air, as not all the heat is extracted by a conventional MVHR, so that air will tend to rise, so the intake always needs to be below the exhaust if mounting them to the lower limit in the regs, as well.

It's exactly what I've done, Peter, and I've read of others doing the same. PH rates seem pretty close to being the sort of ventilation rate we're comfortable with, in fact I'm tempted to turn the background rate down a little bit more, as there are only two of us in what is a fairly high volume house. My understanding (I could be wrong) is that the building regs rates were set to be sure of having sufficient ventilation to remove volatiles given off by furnishings etc, in pretty much the worse case. I would lay money that the MVHR ventilation rates in the regs are massively greater than the real-world ventilation rates for a standard leaky house with just window trickle vents open.

If it's an unvented system then it's building regs that require/suggest the annual inspection, specifically Part G3, and is buried in the detail referred to here: It's the "maintenance of services" bit that often specifies an annual service, for safety reasons, as it's a pressure vessel. The Sunamp has too small an internal pressurised volume to fall within these regulations, so is, AFAIK, exempted from them, under this section of Part G3:

That's just the starting price though. I was chatting to someone that sells cars on Ebay recently (he's a normal used car dealer - if there is such a thing) and he was saying he always starts car listings at 99p, because it means they appear at the top of anyone doing a "lowest price first" search. He sets a reserve price (which buyers can't see) so can't lose out, and generally he reckons that cars sell for around what he wanted in the last 5 to 10 seconds of the auction (snipers, in all probability).

For info, here's my post on the Picaxe forum with the initial test code that just squirts the PM data out to the terminal, although that code may not be relevant to something like Python: http://www.picaxeforum.co.uk/showthread.php?30605-Particulate-sensor-interface-to-any-Picaxe

Funny old thing but I walk through The Maltings at least once or twice a week, and we've eaten in Zizzi's a few times. My gut feeling is that it had nothing to do with Zizzi's at all, but was a fairly volatile agent that was dispensed locally to where they were sitting. If I had to guess, then I'd say it's almost certainly not VX, but might well be something like sarin or soman, as both are volatile enough to have been inhaled by the emergency personnel affected and match the symptoms pretty well, particularly the reports of the officers with itching eyes and wheezing, that's pretty classic low dose sarin symptoms, with the chest muscles just starting to misfunction and some effect on exposed mucus membranes. Fits with the seized hand positions reported and the vomiting, too. Getting back to the sensor, the key is to look for the first two unique start bytes, in ASCII these are B and M. The two bytes after that can be ignored, as they are the length of the data burst and always add up to 28, and the six bytes after that can be ignored as they are the CF-1 protocol measurements for us in industrial environments. The next six bytes are the ones you want, and are, in order: high byte for PM1.0 low byte for PM1.0 high byte for PM2.5 low byte for PM2.5 high byte for PM10 low byte for PM10 If stored in the right order as adjacent bytes no math is needed as the bytes can be concatenated directly to three 16 bit words, one for PM1.0, the next for PM2.5, and the last for PM10, all reading directly in µg/m³.

I worked out that the "MCS installation premium" for a typical monoblock ASHP was around £2500, so your guess looks spot on, you'd never ever recover the "MCS premium" from the RHI, so it would be pointless, just as it was for us.

What you get depends largely on how big your heating requirement is. By using the real figures for our house, the RHI was around £85 a year for seven years. If I'd bent the rules and pretended that our heating requirement was a lot higher, then we could have got a larger RHI payment. Two of the heat pump installers we approached for a quote (before I found a cheap unit on ebay) "officially estimated" our heating requirement as being between 10 and 30 times greater than it really is.................

@jamiehamy, thanks, that's a good point, my language above was sloppy, I think what I meant was propping, so I'll edit the post to make that clear.

@recoveringacademic, Given that you've been at the (very) sharp end of the learning curve with Durisol, apart from the great help that's been to anyone reading this forum, do you think there's any chance of your experience being incorporated into the procedures that they teach? From what I can gather, Durisol have been pretty reasonable in dealing with your problems, that seem to have been mainly poor installer practice, not a failing of their system, or a failing by you (few self-builders would go so far as to attend a manufacturer's training session as I think you did). It seems there would be a big benefit to them in making the need for propping in some circumstances (i.e. when a wall isn't going to be filled immediately) a part of their standard instructions.

I wholeheartedly agree with @billt. Some of our older LEDs (now replaced) were running at around 80 deg C quite happily, without problems. The problems aren't really the LED, but the heat in the LED driver, so if you can fit LEDs with a remote driver, away from the heat source, then the risk of damage, even when running with the stove lit, or emitting residual heat from having been lit, should be pretty low.

I've got as far as testing the PMS5003 sensor and obtaining data from it for three particulate sizes, PM1.0, PM2.5 and PM10, in units of µg/m³. Not hard to do at the hardware/firmware level. I got caught out by buying some fake temperature/humidity/pressure sensors from a well-known auction site (supposedly BME280's, but in reality they were just junk) and am awaiting the arrival of some new temperature/humidity sensors. One lesson I learned was that the BME280 is not easy to work with, as it needs a lot of 32 bit math to correct the raw data to anything meaningful, and that's not at all easy when using an 8 bit microcontroller! I can recommend the PMS5003 as a particulate sensor, though, as it's very easy to use indeed. It outputs 32 bytes of data, including a two byte identifier, two bytes indicating the length of the data burst (which seems fixed at 28 bytes of data), 28 bytes of data for each parameter, in the format high byte then low byte, to form each 16 bit data word, then finishes off with two check bytes. I'm just reading the three atmospheric monitoring data words, data 4 to data 6, that give PM1.0 to PM10 data in µg/m³, as that's all that I think I really need.

This is probably the most relevant entry about getting the big ducts out through the walls: http://www.mayfly.eu/2014/04/part-thirty-mvhr-details/ With hindsight (wonderful thing..............) I'd have fitted the ducts BEFORE the insulation was pumped in, but I wasn't sure where they were going to have to go.

I fitted standard pipe clips at the right spacing to support the pipes under the top member, or fixed them under the floor on spaced off pipe clips (to help avoid pipes being accidentally hit by screws or nails coming through from above. I've just checked my photos, and can't find any really clear ones that show this, as I fitted the acoustic insulation in pretty much at the same time as the ducts, so that hides the fixes, I'm afraid.

Brick cleaner won't dissolve it, as it's dilute hydrochloric acid, however, I believe that gypsum should be soluble in dilute sulphuric acid (battery acid), and it has limited solubility in just water. Acetic acid (vinegar) may also very slowly dissolve it, but that's really about it. If it were me then I'd try dilute sulphuric acid, at about battery acid strength, on a small area and see if that works. It's unlikely to work quickly, I'm afraid, as the solubility of gypsum in it isn't that good.

Bear in mind that there are rules defined in other regulations for supporting wiring and pipework, so my guess is that joist manufacturers don't see any need to repeat these in their advice.

As I understand it, Posijoist licence the construction method to several companies, so it may well come down to who you buy them from as to what guidance you get. Some manufacturers do publish some pretty comprehensive guidance on fixing them, but I think most people just use their own ingenuity when it comes to how to secure stuff. Pipes and wiring are easy, as they both have their own fixing rules in their own regulations or general trade knowledge that govern things like fixing types and spacings, it's really just ventilation ducts where you have to make up your own methods of fixing. I used a combination of perforated steel strapping and lots of big cable ties when I installed ours.

Me too, Peter. The disparity between SAP and PHPP is massive, and it's SAP that seems to have significant errors when dealing with houses that are very energy efficient. PHPP gave a prediction that was pretty close to our actual house performance, SAP is just bonkers when it comes to the heating requirement!

I think we've discussed this before, and worked out that getting to around A94 to A96 was about as high as you could get without adding renewables, but it does depend to some extent on the shape and size of the house (big square houses are easier to get a high rating that small, long and thin ones, for example). One thing I did ages ago was to get hold of a free copy of FSAP and run through some changes like this to see how they affected the rating. In our case airtightness and MVHR made a very significant difference.

It doesn't inspire confidence in the system, does it? Still, a £300 saving a year is a definite win!

Brilliant news, it will encourage all the others who find themselves in a similar position, too. I'm convinced that the methodology used by the VOA to calculate floor area is flawed (no pun intended) as they base it on external dimensions, with a baseline wall thickness of a 1991 cavity wall, so around 250mm. They also seem to just ignore protusions from the house and use and overall outline taken from the ordnance survey data (or did in our case until I sent them detailed floor plans). Great result anyway, and in your case it must be nice to get some good news.

Sorry, I misread DPP as OPP earlier. The architects design will have been produced to fulfil a brief/contract with the original plot owner, so the plot owner almost certainly has assigned rights to use the design. The question is whether or not those rights are transferable to a purchaser without a fee, and that's something you can only find out by asking. Publication of the design is a red herring in this case, as just because the drawings appear on the council planning website doesn't have any effect at all on the assigned rights. The only way to find out is to ask, and in the first instance I'd ask the vendor if the assigned rights he holds to build the house to that design are transferable or not. I suspect not, but you'll only know for sure by asking.

The first point is that enforcement of copyright can be a pain, and there is a massive amount of copyright abuse in the UK, anyway. A lot depends on what the drawings were produced for. A set of outline drawings for planning aren't likely to be much use to someone building the house and producing major components, they would need a lot more detail. If the architect hasn't assigned rights to the person having the house built and they then build it to his design, such that a reasonable person would recognise the architects design in the finished house, then yes, that would probably infringe the architects copyright. Same for the last case, although far less likely, as there would most probably not be any significant house design on an outline permission submission, only a very rough outline of where the house may be and roughly what size and shape it may be, etc.

The design almost always remains the intellectual property of the architect, not the land owner, even though the land owner paid for it. When you contract with a designer or architect, what you are buying is a one-time right to use their design, usually. Often this is a non-transferable right, but it may be that the plot owner was far-sighted enough to obtain a transferable right, you'd need to check. Copyright has caught me out before now, as has the assignment of rights. I wrote an article for a magazine years ago, and because I didn't understand the way assignment of rights worked, I accidentally agreed to assign them "all rights" when I sold them the article. They published in the UK magazine, then a few months later went on to use the article in their big US sister publication. When I rang them to ask about payment for this, they pointed out that I had assigned them "all rights" in the original contract. A hard lesson to learn. Since them I've only ever sold articles with "limited UK rights only", usually one publication only, which stops companies doing this. If they want to publish it a second time, they have to come back to me and negotiate another fee.