fehguy
Posts: 1
Joined: Wed Feb 13, 2013 5:08 am

Re: RPi controlled central heating

Wed Feb 13, 2013 5:10 am

old topic, but maybe this will save somebody who finds this via google (like I did). I took a raspberry pi + phidgets and made an OSS hydronics heater with android monitor app. The source is here, hope it helps somebody!

https://github.com/fehguy/swagger-for-the-home

rooster1
Posts: 17
Joined: Tue Feb 12, 2013 8:55 pm

Re: RPi controlled central heating

Wed Feb 13, 2013 12:32 pm

harvy wrote:Hi rooster,

Did you get anywhere with this?

I'm looking to do something similar (i guess everyone is but in their own way!)

For me i'm looking to have 1 or 2 temp sensors per room, and a solenoid/valve of some description for the radiator/underfloor heating.

Allowing control of each room independently and on its own timer (eg if i know that a particular room is only used between certain times, it only heats around those times),

With scope to expand to hot water cylinder in the future - using a combination of solar heater and gas boiler to heat water most efficiently...

Getting the boiler on/off i don't have a problem with, I've had enough fun and games with thermostats/programmers to know what i need to do to get the boiler to fire and to open zone valves etc (though looking to get rid of the zone valves and route water by use of solenoid at the point of heating may be easier) but not sure on the temperature sensor and solenoid control...

Just wandered if you had any joy with any specific combos of breakout boards and sensors which would help me aim in the right direction? Haven't even purchased the pi or breakout boards as yet, wanted to do a bit more research before spending ££ on boards which i later find arn't useful for my needs!
Hi Harvy

I did get it working to my own satisfaction :)

1 Rpi ethernet and connection to hub.

2 temperature sensors (1-wire ds18b20(?))

1 monitor for elec meter

1 GPIO powered relay in place of the main thermostat

The temp and elec data is uploaded to a webserver every 10 secs and plotted and whether the heating should be on or off is downloaded likewise. The gpio then turns on or off the relay controlling the heating. I set times/temps etc through my web interface.

It all works but I am waiting to 3d print a cover for the relay as it's 240V, so I have only tried it out rather than using it every day.

R

samighi11
Posts: 46
Joined: Wed Apr 17, 2013 8:27 pm

Re: RPi controlled central heating

Wed Apr 24, 2013 7:34 pm

Can you post a diagram or picture. I believe I have all of this working off the GertBoard. I have two DS18B20s in series reporting temprature. I have Relay 5 and 6 working of a simple set temprature. But i am confused on how to wire and replace (in-place) the thermostat. From all the diagrams I have seen, the 24V contro voltage for the value goes directly to the value. the Thermostat (I have 8 zones) then connects the neutrals (one coming from the ground of the 24V and one to complete the return circuit), completing the circuit. Although i am an eletrical engineer by education, I fail to see how this can be connected to the relay, except the obvious. the relay has two load leads (N.O. vs N.C.) in the darlington array of the Gertboard. Would I just hook up the ground wires in the wall (to the current thermostat) and remove the thermostat and I am operational? Is it that simple?

in the late 70s and early 80s/energy saving days, non-linear heating programs was used to predict the start up time required and reduce it. my main initiatve is the modern thinking that if you keep the room at 72 all day it is more efficient. (seperate try is to read my gas meter remotely to prove it).

cpyarger
Posts: 2
Joined: Thu Jan 03, 2013 8:21 am

Re: RPi controlled central heating

Tue Sep 17, 2013 5:47 pm

I have my Rpi-Thermostat project up on github.

it uses bash, html and php
https://github.com/cpyarger/rpi-Thermostat

Any suggestions or improvements are welcome

Warmest Regards,

Chris Yarger

jemtaylor
Posts: 20
Joined: Sat May 25, 2013 1:37 pm

Re: RPi controlled central heating

Thu Sep 19, 2013 3:53 pm

Hi,

I've just written a brief description of my own Central Heating control....

http://fudgetech.blogspot.co.uk/

It's a very simple set up and has been running for a couple of months now. My next phase is to add temperature sensing

cheers

Jeremy

jemtaylor
Posts: 20
Joined: Sat May 25, 2013 1:37 pm

Re: RPi controlled central heating

Sun Sep 22, 2013 10:05 am

I've updated my write-up of the central heating project with some pictures and code for the controller....

http://fudgetech.blogspot.co.uk/

cheers

J

jemtaylor
Posts: 20
Joined: Sat May 25, 2013 1:37 pm

Re: RPi controlled central heating

Sun Jul 27, 2014 12:02 pm

Hi,

I've made some further updates to my blog. The Pi now has wireless temperature sensing throughout the house and of the hot water tank using XRF radio modules configured as temperature sensors.

cheers

J

User avatar
Shoka
Posts: 147
Joined: Sat Jul 12, 2014 8:35 pm
Location: Manchester, UK

Re: RPi controlled central heating

Sun Jul 27, 2014 5:56 pm

Noticed some questions back up this thread about controlling Ferroli boilers, and the meaning of "voltage free contact"

Basically, the Ferroli (like many boilers) has a pair of screw contacts on the edge of the controller PCB, that are shorted out by a copper link.

If you remove that link the boiler will not come on, unless the frost stat trips.

If you short that link, what happens depends on the settings of the internal controls on the boiler.

In effect the internal timeswitch and internal thermostat are in series with that link, so the boiler will only come on if all those other control sources are also asking for boiler on.

What the manufacturer means by voltage free contacts is in effect making or breaking that short.

Very specifically not applying a voltage of any sort to those pins.

A set of relay contacts for instance can be arranged to make of remove that short controlled by an external control system.

I'd avoid using a solid state relay for this, they have a small leakage current when closed, and the how the boiler senses the open/short state of that link will determine if that leakage is sufficient to confuse the boiler into thinking the link is always closed.

If the internal boiler timer is set to be always on, and the internal thermostat is set to max, the boiler is effectively under control of that relay.

With those internal controls enabled, your external control circuit can only force the boiler off, not force it on.

Sensible people wire this up so that the first thing the wire pair from those contacts meets is a two pole, three position, on off on toggle switch.

The boiler is connected to the common pins of the switch. One pair of pins is shorted out, the other pair of pins goes off to your control system.

Thus with that switch in the center position, the boiler is forced off. With the switch set to the shorted pair of pins, this is equivalent to the manufacturers default shipping position with the pins shorted, and the boiler operates as if your external control does not exist. With the switch set the other way the boiler can be held off by your control relay.

At no point should any voltage, either low voltage from the pi, nor mains voltage from some of the available thermostats, be applied directly to the boiler control pins. It 's a bad idea to connect any of the pi's circuitry to those pins, the voltage and current that the boiler controller uses to sense the presence or absence of that short is undefined, and very probably enough to fry your pi.

This is a common scheme, and I know the scheme in use by some of the Ferroli boilers (I have one) but close inspection of your boilers handbook is called for before making any connection. If in doubt, call a boiler engineer.


Cheers Harry
Cheers Harry

jemtaylor
Posts: 20
Joined: Sat May 25, 2013 1:37 pm

Re: RPi controlled central heating

Mon Aug 18, 2014 4:16 pm

Hi all,

I've now added wireless temperature sensing to the Pi central heating controller I built last year. I have three sensors, two in rooms in the house and one attached to the hot water tank. The Pi listens out for the radio messages from the sensors that are transmitted every five minutes and writes them to the database. The controller can now find out what the latest temp is and switch on or off accordingly.

I've put a brief write up on my blog....

http://fudgetech.blogspot.com/2014/07/t ... since.html

cheers

Jeremy

kondor101
Posts: 1
Joined: Mon Nov 24, 2014 10:29 pm

Re: RPi controlled central heating

Mon Nov 24, 2014 10:31 pm

Hi Jeremy. I really like the stuff you have done with logging boiler stats. Can you tell me, does your system turn each radiator on and off individually or does it work as a complete system?

jemtaylor
Posts: 20
Joined: Sat May 25, 2013 1:37 pm

Re: RPi controlled central heating

Fri Nov 28, 2014 5:14 pm

Hi,

No - it's a simple on/off switch for the whole system with a switch for the Central Heating and another for the Hot Water. I have three wireless temp sensors one of which is in the main room and controls the heating. A second sensor is strapped to the hot water tank and provides the input for the hot water control and a third is for monitoring the outside temperature just for curiosity!

cheers

Jeremy

User avatar
rpdom
Posts: 17712
Joined: Sun May 06, 2012 5:17 am
Location: Chelmsford, Essex, UK

Re: RPi controlled central heating

Fri Nov 28, 2014 5:39 pm

jemtaylor wrote:No - it's a simple on/off switch for the whole system with a switch for the Central Heating and another for the Hot Water. I have three wireless temp sensors one of which is in the main room and controls the heating. A second sensor is strapped to the hot water tank and provides the input for the hot water control and a third is for monitoring the outside temperature just for curiosity!
Cool! Or is that "Warm"? ;)

I've had something similar running for a few weeks now, but just the Central Heating, not Hot Water. I'm just setting up a senso for outdoor readings this evening. :)

TFSN
Posts: 7
Joined: Mon Jan 22, 2018 3:35 am

Re: RPi controlled central heating

Sun Mar 11, 2018 9:39 pm

I see some cool projects above. I have a system setup for my greenhouse using combinations of thermal masses, hydronic circulators and about 35 different 1 wire sensors. Heat for the masses is provided via a wood stove. All of this is solar powered and so far, using an 8 relay board... Noticing there is room in the GPIO pins for one more 8-relay board, I likely will add the second to run solar tracking, irrigation, etc.

I have also built the pi into a nice waterproof box with 2 fans, 1 one the CPU, and one for exhausting the box. The CPU fan cools the CPU directly, the exhaust fan has a sensor in the box that triggers it seprately. I anticipate some pretty extreme temperatures during summer months. Here's a video and a link to my youtube channel:

I hope this info helps someone:

Video:
https://www.youtube.com/watch?v=3-BqUfC8VEs

Channel: https://www.youtube.com/c/TheFarmacySeedsNetwork

Return to “Automation, sensing and robotics”