dnb

I think a solid state differential pressure sensor like a MPX2100DP, or a lower pressure alternative like MPX250DP would be easily good enough to see the pressure difference across the valve. The differential element is nice because only the pressure difference matters to the sensor - you aren't having to calibrate two sensors measuring absolute pressures. You can still drive them easily enough from a microcontroller or Raspberry Pi etc. (I used one once to make a high accuracy tank level sensor). The maths to calculate airflow is easy enough too. More or less the same as some aftermarket car engine management systems I've played with. I think I too will be following the example when I've got something built above ground.

Good call. The floor needs approx 1000 blocks. The wall build up is small in comparison.

Day1: The diggers gather like vultures. The old bungalow is doomed now with only one more day of asbestos removal on the inside. The driveway can't be finished until the rain stops. Day 2: Half the house appears to have gone! It seems there isn't much to it that isn't rotten. Another view of of the half-a-bungalow. Skipping a day to day 4: All the house down with the wood awaiting collection. All the asbestos roofing felt has been stripped and removed from site. The pine floor (front of frame) is retained because I can see uses in the future. Day 5: Site graded and ready for building the new house. The tall house in the background is a neigbour's self build from 10 years ago.

I have just got all my piles installed - blog photos will be up soon - and am preparing for the ring beam to be completed. I have a plan, section drawing and buildup scheme worked out with my architect that makes sense and meets my requirements. I now come to find the parts and I have a few choices to make so am looking for a few words of wisdom. The inner leaf is specified as 215mm 7.3N block work, a 60mm cavity and an outer leaf of 100mm blockwork. The beam and blocks sit on the inner, followed by another course of 215mm wide blocks. The sole plate of the SIPS panels sits on these blocks. (Note I have neglected DPM, telesope vents etc for simplicity in this description.) I have found 215mm dense concrete blocks locally, but they are hollow. I don't much like this for either the sole plate attachement or supporting the beam and block. The next option in dense concrete is a 140mm block and a 100mm block together. With mortar, it's more like 225, but there is space on the beam to accomodate this. The third option is a thermalite hi strength (or the Celcon equivilent) 215mm block. It looks like the easiest option but various people have warned me off these (reasons seem vague) I can't find any 215mm solid concrete blocks locally. And I probably wouldn't be able to lift them even if I could! I am leaning towards the light weight blocks at the moment because they have the right material specification, are a little better at insulation and will be easier to ship and handle. (The shipping is always a concern when you live on a small island serviced only by ferry.)

The geocells were fairly easy to use. You'll need at least two people to peg them out effectively otherwise they try and fold themselves up again, and bolting them together with the supplied nylon bolts is one of the most tedious jobs in the world! It's worth spending effort on the grading and levelling because you can "lose" a lot of stone in hollows that the panels will just span. Cutting the panels into shape is again easy enough. I used a pair of tin snips. As ever it's worth planning the cuts carefully because the panels will change shape once cut - you soon get the hang of this. And one final thing - don't ever accidentally pick an edge up with the digger! You'll never get it back down without removing all the stone from the area. (That was a fun half a day of manual shovelling!)

One of the more onerous (read expensive) planning conditions related to the driveway design and protection of tree roots. We were required to install a "no dig" foundation layer using Core geocells (or similar) after the planners were happy with the site fencing, but before the old bungalow was demolished. Typically the planners said "no" the first time we applied for discharge for no readily apparent reason. I re-applied having done more work for an unrelated condition and they said "yes". Braced fencing and signage seemed really important to the planners. So I have lots, all bought for bargain price second hand. We didn't spend much time on site in 2018 or the early part of 2019 because of a perfect storm of family things and working away from home. The winter of 2018 was not kind to the bungalow. there was a lot of rain and several periods of extremely high wind. This redistributed the roofing felt over the lawn and caused the very rotten parts of the structure to collapse. Everybody needs a site office! A bargain £250 caravan will do nicely for a while. Getting a good start on the driveway. Wooden sleeper edging in place and the first couple of geocell panels pinned down. The first (of many) loads of stone. And my old, but perfectly formed digger. (called Digby) A little while later we have most of a driveway. The other entrance is waiting for the land drains to be completed and for the small swamp to become less swampy. This is however enough access for the next stage of proceedings.

Here are a few pictures of the site from the time we took posession and started to clear the undergrowth and satisfy the planning conditions. The driveway to be. It makes Range Rovers look small. Only a few bits of tree and detritus to remove! The boss hard at work during some tree removal work. The back garden being fenced off after felling a very large diseased eucalyptus. Another planning condition: Social housing for bats!

My (new build) plans currently have the cooker hood extracting to the outside world. I'm begining to think this isn't the best plan for various reasons discussed in other threads (extract volume is large compared to MVHR supply etc... Not really a lot of need to go into all of that again). If I decide against having this simple extract scheme, is it acceptable for building control to use a set of filters in the cooker hood to recirculate the air, and then have the MVHR to extract from the kitchen at the correct rate, but a decent distance from the hob? And will the scheme keep the majority of cooking contaminants out of the MVHR? We do a lot of cooking so need a robust solution.

A bit different here - there are 15 large houses all on multi acre sites with quite a lot of solar PV, all on the end of a long line of (low tension) 3 phase poles. This of course is only one input driving the 3 phase argument. I need a bit more than 60A, but still less than 100A.

Not lasers, but it seems you've met accountants too. I work with radar. I was worried by this too, but strangely the new blue book is rather less concerned than I am. I got accused of being old! Anyway, to satisfy myself I have a reasonable design worked out with a work colleague to mitigate most 415v issues. Building control, the location of the house on the grid and the amount of PV I would like all drive towards 3 phase. For some odd reason building control equate the floor area with power consumption. I would like at least a 10kW peak PV system, so given I am out in the sticks, SSEN are strongly hinting at 3 phase. It's an electric house (no mains gas and no desire to burn things in the house) so I can see their point. My sums say I am close to the limit when the immersion heaters, hob, oven and A/C are all on together on a dark and cloudy day, and I should allow some headroom for the future. 3 phase garage equipment certainly. I have my eye on a couple of things. But the 3 phase heat pump is overkill for anything I am doing.

I am being steered towards 3 phase in my new house. There seems little chance of escaping this so I may as well embace it (while wearing a pair of those long sleeve rubber gloves ? ). It gives opportunities later, and negates the need to beg quite so hard for permission for my desired amount of PV. But I am wondering if there is a definite answer as to how the metering works in a domestic application. My experience of 3 phase billing is limited to my Dad's work where reactive loads were worried about (a half remembered conversation when I was 10 years old), and my old London flat where the supplier would send an engineer round every year when we complained about the £9000 bill because one of the 3 spinning disc meters was going backwards again... (not surprising - fluorescent lights and a lift from the 1950s all wired in the most unbalanced way possible will tend to do that...). These days my 3 phase experience is only using it at work to power my "death ray" toys. I don't pay the bills, but sometimes the man that does gets a bit upset and talks about Triads (apparently not gangs in this context) and it getting expensive for me to play, so I have to switch the toys off and perhaps I would like to go home to the family so he can save on the wage bill too? I am hoping therefore that 3 phase in a house is going to be much more straight forward. I have found some nice 3 phase inverters that claim to evenly output to all phases, and I will look to have a 3 phase immersion heater so I can easily make use of my PV. The snag comes if I try to get the house to achieve zero consumption. Do I need to balance each phase separately, or do I just need to achieve net zero across the 3 phases? The latter is obviously much easier than the former. Does the "borrowing" of small amounts of power below the meter resolution still apply to 3 phase metering, enabling the trick to control the immersion heater load? Or, in practice does it really matter? I have a near teenage daughter and a wife who can empty a hot water tank in minutes between them, so all the solar is therefore spoken for...

The planning permission is to demolish and rebuild. So I will give it a go. Thanks!

I have a small amount of demolition to do on site, specified as a requirement in my planning permission. I am not doing it myself, so wondered if I could successfully get it zero rated for VAT (since it's mostly labour) or could claim any of it when the time comes? It is being done after "official start" has been declared in case that makes a difference. I think the answer is "no" because it's not directly part of the build, but it's worth asking the question because it's a few pounds I don't have to spend!

You lot are making me feel lucky! I used an architect for planning because it's essentially a closed shop here. If you weren't born here you're at a significant disadvantage because your parents don't know their parents etc... Not corrupt, but certainly difficult. They negotiated the minefield very skillfully keeping my house design free of planning interference apart from one consession over real wooden cladding (and 12 planning conditions). They also discussed at length how we would live in the house, what my reasons were for that design and how they thought it could be improved. (They were right in the main so their ideas were incorporated, although the 308m2 floor area is causing me a little grief at the moment!). all for a couple of thousand pounds. I admit that the basis for their work was to "copy out neatly" my CAD drawn plans, but it was money well spent to have the review and get some feedback on things that might end up not working sensibly, and to have access to the contacts within planning. It amused me that I was set "homework" throughout - things like condition discharges and areas to research so building control was easier. I used them again for building control. I wasn't going to initially because it's not particularly difficult, although it is time consuming. But I got involved in a big contract at work and simply had no time. This time the cost was a bit more, but they did a good job. I would have taken much more time to achieve the same or a lesser result, and I would have had nobody to review ideas and keeping me from going too far astray. Hopefully it was a learning experience for both of us - there aren't too many low energy houses here yet - the discussions were never one-sided and he had always found answers for last meeting's questions/concerns. Again, given my work circumstances it does not feel an inefficient a use of money. Now it's build time, and I'm PMing on my own! How hard can it be?

Sorry for not replying sooner. It's hard to get around to everything at the moment! My plan was to wire for many things (blinds, garage door, window indications etc) with the view that I would have to cut funding for the expensive parts of these and implement them later. So the first items are lighting and heating/cooling control. I was considering DMX for lighting on the grounds it's an industry standard and will be around for a while yet. I think I need 23 lighting zones (approx 11 dimming and the rest not) so it will be expensive to use Loxone, it is a potential obsolescence issue Having read the Loxone website and watched the videos I think it can do just about everything I want (at a price!) The first 80% of desires were things like dimmed lights in the hallways in a night mode, one touch control to turn on lights from each bedroom to the kitchen. I was also looking at controlling the DHW immersion heater by reading the electricity meter, perhaps via modbus comms. The last 20% were about fine control over the heating & cooling. Such as using a weighted average temperature for each floor (HVAC is to be zoned by floor) with the weights based on likely location of people and time of day etc to control the air dampers. Their heating control algorithms may of course already do this without me having to interfere, but the documentation is not exactly thorough!

Thanks for the insights so far. It's much appreciated. A friend told me about Loxone light switches earlier in the week. They seem to do most of what I need, albeit at a price. Any thoughts about Loxone as a home automation system? It seems I can use it to do 80 to 90% of what I want to do: 3 zone controls via air dampers on the A/C ducting Temperature and humidity monitoring via light switches in all key rooms that can be used as control inputs Electricity use monitoring and thus immersion heater control to use "spare" PV Music server etc - although it seems they are selling an expensive rack PC with software to do this... (could I just buy the software? I have lots of hardware... ;) ) I wonder how much the system can be customised to cover the last 10 to 20%. Is there practical experience here?

I am working with a local A/C business, but their input only goes as far as supply, technical advice and supply of an FGAS installer. I am taking responsibility for the system working as intended. I haven't settled on a damper control solution yet. None of them do everything I want, so it may well be a case of something that does just enough for buidling control, then work on a home brew solution later.

I am starting to look at ways to monitor air temperature and quality within rooms and can't find exactly what I am looking for. My ideal specification goes something like this: * Cheap - using simple commonly available parts, these thing shouldn't cost much! * POE supply for ease of installation in a new build. (A battery and wireless version would be OK too, but batteries are usually a pest in these things) * Simple TCP/IP or UDP comms with sensible (and preferably open) message format. (The sort of thing you can talk to with 20 minutes of playing with Perl or Python) * Measures temperature, CO2 level, humidity and possibly light intensity as a minimum set. Pollutants would be nice. * Discreet size and shape My idea is to run a set of these and other house sensors on on a dedicated and air gapped network to collect data to assess how well the A/C and MVHR is functioning, monitor DHW tank capacity (naturally with other sensors!) etc in a common building management system. I am looking at various of the open schemes for this at the moment. I can find plenty of home brew examples of nearly what I am after, but there must be something I can just go and buy! Any thoughts? Is there a demand other than me for such a thing in the first place?

I have a cunning plan... The A/C will monitor the temperature of the recirculating air at the point where the ducting blends the air directly from the house and the outside air drawn in from the MVHR. This should be a reasonable average house temperature so set a bulk heating/cooling requirement that accounts for the effective losses (or gains in some cases) induced by the MVHR. In a perfect world where everything is balanced all the time, this will be enough. Unfortunately we're not there so I will be allowing for fitting dampers controlled by the building management system to provide balancing based on air temperature and probably quality within rooms. The algorithms to do this don't look too bad on the back of the envelope on my desk right now. There will also be a damper to isolate the A/C recirc so that the MHVR can run stand alone - reversionary modes are important. The idea is of course to keep things as simple as possible. Otherwise you can start worrying about such things as having to detect open windows and closed doors in order to isolate rooms from the system.

Interesting... I have lots of space, a reasonable amout of time before I need certain things, but live in relatively bad location for logistics. However, I will need some things in large quantities. If the items were to be collected from me, then they would ideally need to be no larger than would fit in a transit van otherwise there are significant ferry fares. I would be most interested in slates, timber cladding, bricks for paving, general timber for stud work, cable etc - i.e. commodity items that are non-specific. I also am not constrained too badly by mortgage funding. Calculated risks aren't too much of a problem as long as I don't generate a cash flow issue.

If I didn't have a large shower, I would definitely want one. Both the current and new houses have large showers. In the current house, the lounge/dining room isn't quite big enough to comfortably have a decent table and a decent sofa arrangement - one or other is compromised - so even a small amount of extra space here would transform the house. The new house is significantly large (300m^2 floor area), but I am concerned now that the plant room will be overly full, so the extra space would be useful there.

Not quite the final design. It's evolved a bit since then to simplify controlling the systems and I've done the maths to size everything now I have heat loss calculations I can trust. The A/C will draw air (recirculating) from the entrance hallway on the ground floor, and also from the MVHR fresh output. This will be cooled/heated as required and distributed to the living rooms. Air will be drawn from the wet rooms by MVHR and passed through the heat exchanger (or not when in bypass mode - it only used under certain limited conditions) and out of the building. This shouldn't (in theory) provide unfair loads to either system and I should have sufficient points to monitor temperature and flow rate to maintain control without too many air dampers.

Yep. If I strictly followed ADF I would turn the MVHR down to achieve the purge rate!

Approved document F (a riviting bedtime read) containst the details of exactly how much ventilation is required and defines the terms. Remember that the A/C is recirculating the air within the house, and the MVHR is exchanging it with air from outside. So it's not a case of dual purposing all ducts. Some will only be required for one job. I will turn my house plan document into a simplified schematic (it's difficult to follow over 3 floors) to illustrate what I mean. There are some games to be played with summer bypass on the MVHR too. I should say my plan involves a Mitsubishi Electric 5kW ducted A/C unit and an MVHR unit.

I am aiming to do much the same. I have located very few people with any experience of this at all. It would be interesting to compare notes. My A/C supplier can see nothing wrong with the approach, believes it will become more common in the future, and will supply me all the bits and commission the bits I can't do, but will not underwrite my system design.