Author Topic: Remote controlling of a central heating system  (Read 355 times)

Gattopardo

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Remote controlling of a central heating system
« on: December 02, 2018, 07:16:26 pm »
Hello, (not sure this should be here of in ctrl alt delete) am looking in to a system to be able to remotely view a central heating system temperature and maybe turn the system off and on.  This is to be done via laptop or mobile phone app or web page.  So the idea of some sort of home automation.

The first hurdle is that the property is in a different country. Would that have an effect on the system I can use? Have looked in to the hive system as I thought that it was just a thermostat.  But have found that you need a hub, and this is the bit that communicates with you wireless hub and then the internet.  Have found that the hive hubs are not transferable so buying second hand is not possible. Cost is an issue.

That leaves other similar system, but looking at other systems there are the same  limitations with the hubs?  How reliable are the systems to be left running.  Do they crash or need rebooting?

If I go for a system based on a pi zero as the main controller of the thermostat on off relay (Raspi Nest), then either anther pi zero with a temperature sensor (https://www.instructables.com/id/Raspberry-Pi-Home-Heating-Controller/) or a small battery powered arduino mini 3.3v temperature sensor (http://www.pihome.eu/).  What would there be a way of taking extra care so that the system is reliable.  Does that mean a different type of sd card, such as the specific CCTV cards or just run a branded card and if there are any problems reboot over the air.  Am concerned that if there is a problem that the default mode would be leaving the property with no heating.  Suppose there could be a spare sd card taped t each pi case and any problems just get someone to swap the cards.

Are there any of you doing anything similar in your homes?  If so what are you using and what has has your experience been?

Kim

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Re: Remote controlling of a central heating system
« Reply #1 on: December 02, 2018, 07:46:03 pm »
I have a Raspberry Pi (model B+) based system that's primary function is visually alerting barakta to things like doorbells and fire alarms, but it measures the temperature and occupancy in each room and controls the heating as well.

The main issue I've had is that the Raspberry Pis aren't long-term reliable... 

(click to show/hide)

In other words, if you're going to use a Pi, you're going to need  a) a plan for what happens when the root filesystem becomes corrupted  and  b) a hardware watchdog timer (the Pi's internal watchdog isn't up to the task).

If there's any risk of freezing conditions, I'd recommend leaving a traditional thermostat in place, wired in parallel with your control relay.  Set it to 5C and forget about it.

I'd strongly advise against rolling your own solution if you won't be physically present to debug it, at least for the first year or so, until it's proven reliable.  It's also unlikely to be cheaper than a commercial solution, unless you write off the cost of your time entirely, and cut corners with things like enclosures.  Once you've put a Raspberry Pi, a custom circuit board, some power supply components, a robust 1-wire interface and a sensibly isolated mains relay in a box you're probably up to about the cost of a Hive anyway.  I think my BOM cost for each module was in the £200 range, but there's a lot of extra hardware there that isn't related to heating control.
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pdm

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Re: Remote controlling of a central heating system
« Reply #2 on: December 02, 2018, 08:08:01 pm »
If you just need  on-off switches, basic ZigBee hubs are simple and reliable. E.g. Samsung Smartthings (£75, Korean) or Trust Smarthome Octopus (£99, aka KlikAanKlikUit - Dutch). Each switch controlled by the hub - as many as you want - is between 9 Euro and 25 Euro depending on type and quality.
I use such switches for automatic light controls and to control hot water on/off. These hubs apparently have the facility for local previously set up routine execution if the internet is down.
Zigbee wireless range is good, esp with local mesh support.
Internet is needed for programming/phone interaction/control.
If you want, you can also add on ZigBee motion sensors, temperature sensors, security sensors, doorbells, etc etc. For hot water, tank surgery would be required to install a temperature sensor...
Further automation is also possible with IFTTT/Olisto/Alexa...

Re: Remote controlling of a central heating system
« Reply #3 on: December 02, 2018, 08:52:47 pm »
As Kim says, if it’s frost protection for an unoccupied property, fit a, or several in parallel frost stats. 
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