Hello All!

A got a call out from a local church this week.  He was a little concerned with the heating.  He had to switch it on and off by going in here!

It is a sea of botched wiring and plug in timers-truly scary…..!  Anyways, he asked could I fix it and of course I said yes, with a sly gulp!  He wanted the three zones controlling on individual time clocks so I wandered off to the wholesalers!  This is how the job went….

First task was to identify and mark all these pyros.  Next I chiseled through the rusty screws and dropped the panel.  This system had stuff that the church had never used, like vent fans so they asked for it to be all disconnected. All they want is their three heating zones…..

That is more like it!  Notice this box is smaller than the old one. The conduit is now a little short so that was the next job!

Now this is a tool you just have to have!  This is a self levelling lazer.  You can see I have put a dot on the side of the adaptable box ready for the drill.  Just got to set the new conduit by 25mm and cut to length…..

Now we hit rough waters!  All the pyros coming in the top are easy peasy, but this is where I need to be careful!  Because the new box is smaller, these boiler pyros from the bottom are short! What I did was to re-bend them to make them shorter still and gland them off to a metal adaptable box.  Remember, these are old cables with no earth tail, like you see these days.  The earth continuity must be good and it is achieved via the gland.  Tightened up here now, all is well!  It was then a simple job of joining the boxes with a small piece of tube containing  pvc wiring including a cpc connected to the metal box. Here is a closer look…..

Note the cpc fitted.   Also see how I set the different length cables to reach the same spot.  Yes, nice but it could turn ugly if the cable now fails it’s insulation resistance test!  Of course I am kidding- it all tested OK after the fettling!  Notice I have fittted a small peice of ‘din rail’ in the back and fitted what are called ’sax terminals’ .  Makes a real neat job I feel.  Anyway, nearly there now!!!

Now I did cheat here as the lid bit, I did in the garage the day before- a bit like ‘blue peter’- remember that- “Here is one I prepared earlier”  I made up the front, more din rail and sax terminations.  The rail also carries the three relays I need to make this work.  I have terminated all the cables I need and loomed up all the spare ones at the top….That is us all done now….

And so, there we are!  I have put an isolator on the unit for good measure and marked it all up…… Now a brief explanation of how it works.  Basically the power comes into the isolator and then out to the clocks.  Each output from each clock runs it’s respective pump.  As well as running its pump to also feeds the energising terminal of it’s own relay.  The three relays are wired in a parallel  fashion so when the pump supply pulls it in the relay switches on the supply to the boiler.  That way any clock will switch on its pump and boiler without affecting the other zones……. clever eh!

Till next time, all the best!

Alan