DIY Heating interface – evaluation

submission by Steve Jones – I wished to enhance the manage of my central heating system by utilising my house automation controller (HomeVisionPro) whilst still retaining the original central heating timer so it might quickly be changed back on if the controller was down or if I needed to take HV out if we moved.

Having eliminated the timer from its wall plate it ended up being evident that there was a useful wiring diagram on the back which made this job simple to implement. The diagram showed the timer is just two time managed relays. One for hot water as well as one for central heating.

(click pic to enlarge)

(click pic to enlarge)

I decided the very best thing to do was make a little module on some PCB strip board containing two relays to switch the mains present for both HW as well as CH. The 12volt DC coils will be changed on demand from HomeVisionPro… The fuse holder is for a 200ma fuse for the coils 12v supply… For added security I put the 50mm x 50mm PCB in a potting box bought from Maplins as well as potted the board in potting resin…

(click pic to enlarge)

(click pic to enlarge)

(click pic to enlarge)

(click pic to enlarge)

Next task was to chase in 35mm deep single gang wall box next to the existing timer for the module to sit in the back with a status/override switch on the front.

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Using a modular Clipsal switch I decided I desired two push buttons to signal HV so I might override the setting of HW as well as CH (i.e. toggle them on or off). I likewise added an on/off switch to isolate the 12v supply to the coils therefore providing a regional means of disabling HV’s control… I added two neon’s red for HW as well as eco-friendly for CH… These were wired direct to terminals 3 as well as 4 respectfully together with a neutral. In wiring it this method if either the controller or the timer switches HW or CH on the neon’s illuminate. To make it look the part I got a regional engraving shop to add the decals for £8.00

(click pic to enlarge)

(click pic to enlarge)

I wired the yellow (CH) as well as the blue (WH) from the module’s relay contacts to terminals 3 & 4 so putting the relay contacts in parallel with the existing timer, The other side of the contacts go to 240Vac positive. The two 12Vdc coils are wired back to the A ports (relay ports) of HomeVisionPro which supply the 12v supply on demand. The water as well as heating (momentary push) switches are likewise wired back to HV as well as are linked to two input ports with a simple bit of code to toggle the supply to the coils therefore changing the boiler on as well as off (i.e. on push of switch, if boiler on switch it off. If boiler off switch it on….) The off/Auto switch is there to isolate the coils supply in the event the timer is needed again.

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Control – The common boiler timer in now left changed off as well as I utilize HomeVisionPro to manage the boiler. With HV this likewise has the capability to enable manage remotely by other means i.e. IR, RF, the internet, mobile phones ect…. The next task for me is to link up my intruder alarm to signal HV when we are out the boiler can then be changed off immediately if the outside temperature is above a provided temperature.

I hope this perhaps of utilize to some one out there.


(click pic to enlarge)

Parts Used

2 x 12V/12A min Relay – Maplins P/N JM67

PCB strip board

PCB Fuse holder – Maplins KU29

Potting Box – Maplins FD97

Potting compound

Clipsal 5 method Front Plate – lets Automate P/N 10580

2 x Clipsal short-lived switches – lets Automate P/N 10583

1 x Clipsal rocker switch – lets Automate P/N 10605

2 x Clipsal Neon’s Green/Red – lets Automate P/N 10588 & 10589

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