Help with installation / diagram

Hi Alan,


Window frames are hardwood.


Thanks.


Ian.

OK,  copying some numbers from that first attachment,

R2   25.2 ohms 3.5Amax 


R15  25.1 ohms  3.6A max,


R16  21,5ohms 3.5A  max


Total resistance is then  71.8 ohms.
 (please double check that and measure the actual total resistance of the chain before energising anything at all)


230v across that combined resistance will give  230 /  71.8 = 3.2 A so it will run a little cooler than the absolute max rating, but yes it will  not overload anything, should be as safe or dangerous as the maker's original single phase proposal.


Is there no controller supplied at all ? If so then anything that can key mains on and off , either the elements direct or via the SSR will do, but I suspect you are supposed to have  two sensors, both to cut off at a preset temperature, one for room temp and a 'save the glass' one set to cut off at however hot the glass is supposed safely to get on whichever panel in the chain gets hottest.

If testing manually,  I might look for a stick-on thermometer just to see how hot the glass gets. I'd expect the glass to have a thermal time constant of no more than a few minutes to stabilise - while the room could take some hours.

Is the planned window sensor location on the north or the south side of the building or possibly even the east or west?


Andy B

Hi Andy,


The back of the church is South facing so the planned sensor downstairs was in the south R30.

Upstairs was North R4 and East R15.

The window fitters were told to embed the sensors in the frame which they did (but they don't record the correct temp - ntc sensors).


Ian.

So are the window temperature sensors going to cut the heating off to the north facing rooms when the sun shines?

I know a room sensor could do the same,  but I was just considering the purpose and operation of the sensor, because I can't see the windows getting to hot unless the sun is shining on them.


Andy B

Hi Andy,


This is what the guy who did the diagram emailed me initially:

'There are two groups of heating glass in your installation and they are controlled by two temperature controllers that are working as a thermostat with a sensor on the glass. When the required temperature is reached then the power will be cut off.

When the sun heats the glass then also the sensor commands the processor to cut off the power'.


I assumed only 2 of the 3 sensors could be used so the south one for all the windows south & west (controller 1 on consumer board) and either the north or east sensor for those (controller 2 on consumer board) - so just 2 zones which was not what I asked for and pretty impractical - hence wanting to try and hook them up to a room stat on a room by room basis (somehow?)


Ian.

 

All sorts of random thoughts.


There isn’t any bathroom windows, I presume the bathrooms are all windowless.


That could be an advantage as I presume you cannot have any curtains. Not having curtains or internal blinds is not an issue on the continent, because they have external window shutters which completely obscure the view into the house or flat as well as giving additional thermal and sound insulation, as well as improving security and shading rooms on sunny days.

I have only ever worked on one house in the UK with continental style exterior powered shutters, they would seem to be advantageous when used with heated windows.


Andy B.

If you know the type of the NTC sensors actually fitted or can measure them, then there may be hope of using them, at least as a simple overheat cut-off with a normal room stat in series for room temp control.

With the right combinations of resistors the common NTC sensors can be configured to generate a voltage linear versus temperature over a respectable range perhaps 10-30 degrees with a bit of an S shape outside that - but that does not really matter that much for operation.

(what you need is sensor resistance readings at a few temperatures, then a bit of curve fitting mathematics, which I can help with )

As I carefully and straighforwardly pointed out before, if the windows do have the IR reflective coating on the outside pane you will not get huge solar heat gain from most of the spectrum. I doubt that heat will be the problem and anyway the ventilation system should be able to deal with that with suitable controls. I don't see why you have temperature sensors near the windows either, you will never get too much heat from the glass unless the whole room is too hot, and with the power rating and safe surface temperature requirments it is not possible. I am with Mike that you may have something which does not work.


There is a second point, and that is that everything past your control cabinet intake is an "appliance" and not really fixed wiring. Each window is not separate if they are in series. BTW flexible cables may be used anywhere you like given ratings etc. they should not have to be replaced at all. The whole system should have RCD protection at 30 mA. There is nothing wrong in following BS7671 for the wiring, in fact it is probably a good idea, but you do have a slightly strange beast here!

I don't see why you have temperature sensors near the windows either,

There have been reports of such windows shattering of their own accord - I'd guess there's limited scope for the glass to expand within a sealed unit - so possibly the sensor is intended to prevent the glass itself getting too hot and so limit internal thermal expansion?


    - Andy.