Help with installation / diagram

That’s why I was asking how many RCDs there are, because they are not extra low voltage circuits.


Regards the cables to the windows, I think it just needs to be accepted they need replacing whatever happens.


Andy Betteridge

Back to the heat loss Andy. You are right about possible new build with maximum insulation, but these are few and far between, it is impossible with timber frame (at least at reasonable cost) because the timber is much worse than the insulation between, and building cavity walls with large cavities has structural issues with the wall ties and the window openings (because these are less well insulated).


Over to the temperature sensors, I think it is extremely unlikely these are PT100s, but you can tell by looking at what looks like thermostat controllers in your cabinet, they usually say the type of sensor to use, Measurement of the odd degree or two is quite difficult with these sensors, the point of platinum sensors is that they have a high melting point so are used for furnace control, and sometimes where extreme accuracy is needed but with a lot of complexity and specific calibration.  It could be that some type of standard thermocouples are expected but you need the information, again the electronics are usually marked as there are a number of options and types.


I have not changed my view that these windows probably do not work, but an interesting test would be possible. Get a radiant heater and point it at the outside of a window. Can you detect any heat on the inside of the window, perhaps 150mm away? If there is any I suspect that there is no IR reflecting coating on the outside pane, so the heat loss will probably be of the order of 50%. You could also try the other way round, but you will probably be able to see the coating if you look from all angles very carefully, it usually shows as slightly greenish at some angles, but this look is not definitive as the heat test probably is. An IR thermometer would also not work well through this window if you have a clinical one available.


Back to the electrics, you have 3 windows available presumably. Connect them in series and to the mains. See haw much heat comes from each side, your body is very sensitive to LW IR radiation and you will feel something. Again there should be NOTHING from the outside side of the window. It is not worth spending any money unless this is actually going to work properly, and you don't want to finance a failed experiment, particularly if the available cash is low.


The world is a very difficult place nowadays, and there are all kinds of scams out there, and particularly in "low energy" and "Green" with all kinds of claims made. Whatever you do electric heating is expensive, as is loads of insulation and every other thing to increase the cost to make it practical. You will see more discussion on the IET Savoy place virtual club forum (under forums above) about the cost - benefit of electric everything. Properly costed many of the electric Britain claims are unafordable, particularly after the Corona Virus. I hope you are not attracted by solar panels where you live, they are virtually useless at such latitude because of the low sun angle and shorter less sunny days. The salesman will say anything to sell, but there is no comeback when you get less electricity than he says, the excuse being the  weather of course!

Back to the heat loss Andy. You are right about possible new build with maximum insulation, but these are few and far between, it is impossible with timber frame (at least at reasonable cost) because the timber is much worse than the insulation between, and building cavity walls with large cavities has structural issues with the wall ties and the window openings (because these are less well insulated).

Ways and means are being developed - "teplo" ties have been used for masonry walls with cavities containing up to 300mm of mineral fibre insulation - and there are a number of techniques for reducing the cold bridging of the timbers in timber frame construction - for example some use timber I-beams rather solid timber for the studs (so only a few mm of ply forms the bridge) - others place a continuous layer of insulation over the outside of the frame which is then rendered over. Keeping the U value of windows below 0.8 (triple glazing and thermally broken frames) normally prevents any issues with condensation on or around windows. Yes a lot of this is rather new to traditional builders, and there's a lot of detailing that needs to be got right if a lot of the hard work isn't to be undermined - but it is doable and is happening. If you look at the self build market this sort of thing has been common if not quite mainstream for at least the last 10 years.

 

at such latitude because of the low sun angle and shorter less sunny days

Actually summer days get longer as you go north - it's only the winter days that are shorter.


   - Andy.

Take a look at the Denby Dale PassivHaus for a good example of a well performing traditional cavity wall construction - as Andy mentioned, wide cavity ties (with BBA certification) such as Teplo are common on 300mm cavity. I don't need UK certification, but I'm looking at a similar design (albeit with 200mm internal block) for a house in France (500mm wall thickness overall). Excellent winter performance and good internal thermal mass for summer performance  - nice deep windows (from outside, with shutters) to get good shading, coupled with roof overhang of 500mm. I've got space for a lot of roof integrated PV, so actually targeting net zero carbon on an annual basis (including my car charging) coupled with currently an ASHP (but investigating water source as I can get a borehole down with the local "well" company to the water in about 12m depth (a well on a neighbouring site has some pretty good draw down characteristics in terms of flow rate down to about 20+ metres


Not the sort of thing the mainstream house builders are doing but certainly fairly common in the "self build" and "green client" fraternity


Regards


OMS

davezawadi:

 I hope you are not attracted by solar panels where you live, they are virtually useless at such latitude because of the low sun angle and shorter less sunny days. The salesman will say anything to sell, but there is no comeback when you get less electricity than he says, the excuse being the  weather of course!

Try modelling the system in something like PVGIS (which also allows you to enter a representative of your actual horizon.


Given that a passive house is at 15kW/h/m2 per annum, it's surprising, even up north, just how much you can wring out of PV coupled with a good heat pump and a bit of buffering.  It's not all about "I can do everything" with my PV, more that "I can shift a considerable chunk of import" with my PV


Obviously that does presume we have a grid that's working in the dark


Regards


OMS

A few years ago I went on an EU funded domestic property air tightness training course that was being run by Coventry University, had the UK government not backed down from enforced upgrading the standard of new build homes in the UK we would be having all sorts of different discussions now about installing cables in new build homes. 


Andy Betteridge

Hi,


Further on from my initial post, today I have by chance stumbled upon some diagrams left by the original electrician (never seen before).

I can only assume they where sent with the changed consumer unit.

Looking at the diagram it seems like the windows are trying to be grouped together as close to 240v as poss except for the last group (would this be what the transformer was intended for?)

Would this mean in theory you could swop around the configuration on the same basis? i.e as close to 240v as poss in series?

Not sure it will make any difference at all :-(


Ian.

Well, if, and only if, the groups are such that the currents in any one series chain are all identical, and also then the voltages in that chain do add up to 220-260 ish then yes it makes a lot more sense to omit the transformers.


You will still need to get a 110V transformer, but now only the one, and at a far more modest rating. (110V 5A would be about 10kg for double wound, half that for an auto transformer where the output is not isolated from the input )


Given the back story I do not exactly have a good feeling about it I'll be honest, but it does explain  what has been supplied so far and it has the feel of 'just maybe' .

Perhaps nonsensically If these had been the first drawings you posted, I'd be happier....



not out of the woods but the fog is lifting.




Some niggles remain.


When it all comes on, It is still a big load - if the underfloor heating is electrical it may well be either/ or, not both at once (or a supply upgrade)


Also is there anything at the windows that needs earthing ? Two core flex is OK on things that do not need an earth, but NOT otherwise, and is not really right for fixed wiring, except as an appliance flex.


And another hurdle, do you have info for the thermostatic controller - does it really need a PT100 ? I still find that a bit of a remarkable choice, but maybe if it is an industrial module inside that has been re-purposed .


For now I'd see how practical it might be  to wire into those 240v groups and leave the 110V set unconnected.

Before that I'd take the Volts and amps table out of the first group  of files you posted, and check that the numbers do add up in the new series config.

It is safer if it errs on the side of a total chain voltage that is a bit high so the current is a bit lower.

Hi Mike,


Many thanks for the detailed reply.

With regards to the thermostatic controller - I have no details - the PT100 sensors where never ever sent. I was hoping there may be a way of using a wireless thermostat to control the groups somehow?

The UFH is wet UFH running from a thermal store, so no boiler installed (it does though have a 6kw & 3kw back up immersions fitted).

I'm just interested in getting the upstairs ones working and so reduce the load somewhat.

Refering to the diagram - in group 1 it shows R1-2-6 in series (I only need R2)

Then in group 2 it shows R14-15-16 in series (R14 not needed).

Would it therefore be feasible to connect R2-15-16 (as R2 very similar to R14) with the already spec'd R17-18-19 then test them as a group?


Thanks.


Ian.

Are your windows wood, metal or uPVC (plastic) as this may suggest whether you need an earth or how hot the windows are allowed to get. It may also suggest why you need temperature sensors on the windows rather than in the general room area. 


Regards,


Alan.