MikeSharp01

Just posted this on another thread thought it had better be here as well: We have the passive slab, will have the ASHP, so now if I can find some small fan coil units, we have only vaulted ceilings with a small flat spot at the top which has limited room but I found this fan coil unit: Image: https://www.hitachiaircon.com/hk/en/ranges/airside-systems/fan-coil-unit but I cannot find this on any Hitachi / Johnson controls UK site but scaling from the inlet/outlet pipes we might get it into the ceilings. Anybody recognise it?

2 hours - I am in the middle of a heatwave wondering how best to cool the upstairs of the build so this is all very timely. Especially given you feel that your upstairs might be 30deg! We have the passive slab, will have the ASHP, so now if I can find some small fan coil units, we have only vaulted ceilings with a small flat spot at the top which has limited room but I found this fan coil unit: Image: https://www.hitachiaircon.com/hk/en/ranges/airside-systems/fan-coil-unit but I cannot find this on any Hitachi / Johnson controls UK site but scaling from the inlet/outlet pipes we might get it into the ceilings. Anybody recognise it?

Why not use the wire to the consumer unit as your resistor and measure the voltage drop across a length of that.

Yes - sorry should have done that.

So it looks like your code is not using interrupts and this means your counter will miss events if the Pi is busy. There are a number of solutions to this Multitasking or Threading using simple call back interrupts. I found this article which covers the latter case and is probably the easiest if you are wanting to stick with python. It has two call backs (your code could be put in any one of them as they both detect a falling edge.) on different pins (17 & 23) and a wait until pressed on pin 24 (which ends the programme). https://raspi.tv/2013/how-to-use-interrupts-with-python-on-the-raspberry-pi-and-rpi-gpio-part-3 So you set up you GPIO (My example uses Pin 17 and you need global counter variables etc as well) import RPi.GPIO as GPIO GPIO.setmode(GPIO.BCM) GPIO.setup(17, GPIO.IN, pull_up_down=GPIO.PUD_UP) Define a call back function def my_callback(channel): print "falling edge detected on 17" # Put you count code here. Load the trigger for the call back # when a falling edge is detected on port 17, regardless of whatever # else is happening in the program, the function my_callback will be run GPIO.add_event_detect(17, GPIO.FALLING, callback=my_callback) #You don't need bounce time for a photdiode it should be clean. Run the rest of the programme as a loop servicing the saving of the counts. As I am working with WEMOS device I will be using a similar approach but in C rather than python.

I think you could use one of the GPIO counter timers to capture without reference to the software them just read the counter at whatever interval and work out the difference since last interval, and accounting for rollover of the counter at the top - not sure what that is 16 / 32 bits or some such. You don't really need the actual time of each pulse just a number at a given time.

Is it working OK if so not sure it needs refining but also not sure it is reliable - have all the bits now to build a WEMOS d1 mini pro based version but a think I will count pulses and return a figure in 1 minute lumps that means I can store a load of readings on the Wemos and upload the whole lot as needed. I can also just have a start time stamp and keep the whole lot lined up with a NTS so storing much less data. Anyway I will get to that next week. Today we party!

Are you in danger of over thinking this! Perhaps choose an average methodology, worst case or even best case (from whoever's point of view.) and stick it in.

Yep - discourse 101.

None taken - don't worry - its all in good part. Back to WEMOS programming!

I wish I had not started this. An IT earthing system is still an earthing system just not traditional and we are already way away from traditional here - EG Malaysia Airlines fight 370 which is not still flying, has been captured by gravity and therefore is, mostly, now at earth potential somewhere - although I agree that differential metal actions, perhaps in salt water, may well be causing some minor differences in potential of some of the parts. Naturally many other interpretations are possible and Ergo (therefore), ipso facto (by that very act / fact), inter alia (among other things) - I give up!

Do they stay up for ever then - eventually the must come down to earth!

Not a good starting place - every installation needs a good earth somewhere.

Not sure about Velux but we have have Fakro and their insulation detailing on the quad units us great look at their website.might give you.some ideas. Air tightness involves sealing the window frame to the air tight layer - is that your plasterboard or have you got a plastic membrane in there somewhere?

Considered and done this could help the whole damned nation.

Alpha+ to that - I mean the document not the marking rubric!

Is that the Passive house measure at 50% of minimum requirement - that's attention to detail.

Yes we did that cost a fortune, £2-3k including the pipe and the gas sign off for the pipe and won't now need it as we have decided against having gas but I guess it's there ready when hydrogen is a thing🤔.

People will be people.

So best part of 1000m for a decent shower @Nickfromwales I hope your friend has deep pockets cos he will have deep holes.🤔

I actually don't think you have a problem. I need to find out if the python libraries implement the interrupt driven features but either way as you have the pi doing only a couple of things it will be fine. The problems come down the track if you get the pi doing more jobs and loose track of what is happening where and when in the system.

Close them at the outer end but also protect the cables there as they can be chewed through. I have, in the past used stainless steel wool, oven cleaner type stuff, forced down to simply close the gap, this can be pulled out if needs be, does not rust, allows a little air flow - if you want to seal it to air you have to work harder and cannot be chewed through by your average rodent / vermin!

This won't and pretty soon your corner of the country will be ideal Panda habitat. Or not so slightly - if you subscribe to such things, I don't but its fun reading the output (politest way I could put it) then this article will put you square: https://www.dailymail.co.uk/sciencetech/article-7772477/British-gardeners-urged-NOT-grow-bamboo.html#:~:text=Like the notorious Japanese knotweed,and even cracks in concrete.

This is a great little device, and I will build one but using a WEMOS D1 Mini device, however I guess there must be a rate limit somewhere in this version and if you add in additional meters it will arrive much sooner, if its coming at all. Several concepts could, but don't think they will, indicate that although a terribly simple and reliable idea it may fail in exremis. I am not saying any of this is a problem for this system as implemented but it may be if you extend it without getting to grips with the nature of real time systems. Firstly the RPi OS is not really a real time system so although the quickness of the hand deceives the eye it can only do so much in a given time and probably cannot do things at a given time! You can programme it to give priority to aspects of the code but when everything is competing this become a real art - games programmers will tell you this is their biggest headache - my fraction of the CPU is this and spread over.... Real Time OS's do guarantee timings, it is the definition of a real time system that time critical events are handled. This all means that although the RPi will probably do this reliably it may miss a pulse here and there while it is busy housekeeping - a headless system will take less time doing this naturally and this system is not being asked to operate at very high speeds (See below) So, secondly, how fast does it need reliably to be. Most people have a 100A connection so if one was running that flat out (Approx 17Kw {240 x .707rms x 100A} of resistive stuff running) those pulses are going to be coming reasonably quickly, perhaps 5 pulses per second, and you might worry that your Rpi, usually running with Raspberry Pi OS, is busy doing some housekeeping while a pulse comes and goes without being spotted. This is assuming that the GPIO library does not implement any interrupt based process - if so all this is tosh - someone will tell me (See link below)! The sampling is not really a problem of the frequency of the pulses but rather their length, how long are the pulses anyway? If I can find a photodiode around here I will have a look at my meter and find out! Do they change length depending upon frequency one also wonders? For now I am going to work on 30ms pulses as a guestimate. So you need to guarantee your sample rate at least meets the Nyquist criteria (I was always taught that simplistically you need to sample at least twice the highest expected frequency / period to be reasonably sure you spot everything). So this means you need to sample at least every 15ms to be sure of catching a pulse of light. Rpi can sample at MHz so sounds like no problem but with an non RTS OS you might find that the writing of that CSV file actually takes a period of a of 15ms and you may have missed your pulse. The good news is that even if the libraries don't implement the interrupt driven GPIO functions you can still do it and there is a very good explanation of all this here: https://roboticsbackend.com/raspberry-pi-gpio-interrupts-tutorial/ This world we are living is getting increasingly demanding of the union between mechanical, electronic and software systems. So if you can get the electronics to do some of the work the RPi does not have to be so real time. I think the Rpi has a PIO that can be set up as a pulse counter which you can just read anytime, count the difference - measure the time between and it recycles at the top but I may be wrong on that one.

I have this extractor and with the sander attached you can send plasterboard drywall skims over your lunch no problem. I got it 2nd hand so not ridiculously pricey and it works well. Bags are costly though!