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Thinking about using some relays and a Raspberry Pi to control the central heating as a replacement or in parallel with the current timer. Current timer fits on a bracket/connector which looks like this:
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I presume that's fairly standard?
It seems like too much effort to make something which will directly replace the current timer to mate with that, so thinking about either replacing that or more likely just running additional wires off those connectors which would enable me to run the existing timer in parallel.
My question is whether I'm allowed to DIY this under Part P regs - I'm not seeing any obvious reason why not, but not an expert so may have missed something. Oh and yes I do have a fairly good idea what I'm doing with mains relays and isolating stuff - I plan to have all mains voltages with the relays in a separate box away from the RPi.
you're not adding a new circuit so I think you'll be ok,
what you plan to do isn't really any different to replacing a light fitting (which isn't notifiable)
Not sure what you exactly want to do, but my sister wanted the ability to switch on her heating remotely. They already have a Pi monitoring a PV inverter so I suggested the following:
- Leave the existing programmer and room stat in place
- Switch the heating on to constant (so boiler is always on)
[Do the following with mains power off]
- Open the cable that goes from the CH programmer to the boiler and insert a [url= http://www.ebay.co.uk/itm/SSR-40DA-SSR-Solid-State-Relay-Module-40A-Output-AC24-380V-Input-DC3-32V-UK-/181771912633?hash=item2a527345b9:g:148AAOSwstxVeXFo ]solid state relay[/url] (SSR) into the live wire
- Take any old [phone] charger that outputs 5v and connect to the input side of the SSR (when the charger is switched on the relay closes and the boiler will run)
- Put an [url= https://energenie4u.co.uk/catalogue/product/ENER002-4 ]Energenie remote control socket[/url] into a conveniently located mains wall socket and then plug the 5v charger into it.
- Fit the Pi with a [url= https://energenie4u.co.uk/catalogue/product/ENER002-2PI ]Pi-Mote[/url] and have the Pi switch the socket on and off however you like.
This would allow you to have the Pi control the heating completely (with the addition of some simple temperature measuring) or just allow remote control either via a web interface or SSH.
Total cost less than £30 and easily/quickly removeable if you want to put it back to the way it was.
Not notifiable (in England). In Wales it would be if it's in a special location (kitchen, bathroom, outside).
Rich.
Thanks all - I'm in England and in any case it's in the utility room, next to the kitchen, but not part of it. I didn't think it was notifiable, but thought I should check.
That sounds a lot more complicated than I'm planning, sharkbait - the RPi GPIO should be able to drive mains relays directly (and if not with just a simple relay driver), so no need for remote control sockets or any of that, and I plan to set it up next to the existing controller, wired in parallel with it, with additional connections into those pictured above. Hence no cutting of existing wires and removable in minutes. Existing timer set to off, but if I want to revert to that I just power off the RPi and switch the timer outputs back on - the existing timer can still be used to turn the heat on manually without any need to connect to the RPi. I only plan to replace the timer bit for remote control, keeping the existing thermo - clearly I could add more later, but doubt I will.
Isn't a Pi overkill here ? How about an arduino or (better) an ESP8266 module which has Wifi built in 🙂
Maybe, but it's a lot easier to do an interactive web interface (Javascript/PHP) with a RTOS - I already have some code for controlling stuff that way, I know what I'm doing with a RPi and I happen to have a spare one hanging around (though a RPi Zero is hardly a more expensive solution). No point increasing the dev time for a one-off.
RPi GPIO should be able to drive mains relays directly (and if not with just a simple relay driver)
They certainly can but there's a fair amount of scepticism as to whether it's sensible to do so with mains voltage. The SSR I've got in front of me can be triggered by 3v so direct GPIO control would be OK.
I came up with that solution for my sister as her Pi is in the loft with the PV inverter. I quite like wireless control anyway.