Navitrino Progress

Introduction.
Navitrino is a modular open source project intended for monitoring and controlling domestic energy usage.

Navitrino is an experimental platform, compatible with low cost Arduino hardware, which can be customised to meet the requirements of the individual's home energy installation. Navitrino can be assembled from off the shelf Arduino hardware, and programmed readily using the Arduino IDE.

Today's domestic energy systems are becoming more sophisticated with the addition of solar water heating, solar pV, heat-pumps and the like. Navitrino has been designed to monitor the key parameters of the system, make decisions based on usage, lifestyle and climate conditions and intelligently co-ordinate the various energy sources.

Navitrino was conceived with the following uses in mind:

1. Solar Water Heating Controller - simple control with circulation pump relay
2. Central Heating / woodburner controller - determines best usage of hot water
3. Electricity Monitor - whole house electricity consumption
4. Gas consumption monitor - pulse counter on optical or magnetic sensor on gas meter
5. Battery management system pV / battery charge controller/datalogger for wind or solar pV
6. Gasifier controller
7. CHP controller - engine start/stop, rpm, voltage monitor etc
8. General purpose control tasks
9. Temperature, climate and weather monitoring and datalogging
10. General purpose energy monitor for performing home energy surveys

Navitrino as a concept was intended to be as flexible as possible, so if a new bit of equipment or technique comes available, Navitrino can be extended and updated to cater for the upgraded system.

Navitrino is based on a nework of interconnected nodes. Whilst one device might be controlling solar and domestic water heating, another device may be used to monitor and log the household electricity and gas usage. Devices can share data with one another using a simple serial data format which is compatible with both wired and wireless networks.

Navitrino uses low cost, off the shelf, open source Arduino hardware as the basis of the project.
The Freeduino and accompanying sensor shield from NuElectronics, which has real time clock and SDcard interface provides the hardware.

Alternatively, if the final intention is to incorporate a Zigbee wireless network the "Stalker" board from Seeeduino Labs in Hong Kong also makes a ready to run platform.

Central Heating Controller.

During the summer months I have been slowly getting together all the necessary elements of the Navitrino project; sourcing the hardware, building up the sensors and writing some rudimentary code routines to exercise the hardware.

As we have now officially entered the UK heating season, one of the first projects for Navitrino is to monitor and control my central heating system.

I have mentioned this in an earlier post about using a DIY controller to monitor and control the home central heating system. Now is the time to put these ideas into action.

The task is fairly simple, the controller will monitor the living room temperature using a thermistor temperature sensor, and turn the central heating boiler on and off in order to maintain the living room temperature at a level as set by a rotary potentiometer.

In addition to the room temerature probe and the set-point control, the Navitrino also monitors outside temperature, the hot water tank temperature (2 places) and a light sensor placed in the living room. The idea of the light sensor is that it can be used to determine the living room occupancy - when the lights are switched off at bedtime, the heating will either shut down or revert to a lower temperature setting.

The controller also incorporates an interrupt driven pulse counter, which allows it to count pulse data from a gas or electricity meter - so that home energy consumption can be monitored. I am particularly interested in gas consumption and being able to relate it to central heating usage and outside temperatures.

Over the last few days, the prototype Navitrino has been controlling the central heating, datalogging temperatures and counting pulses from the gas meter.

Originally, I used an opto reflective sensor to detect the "silvered zero" passing by on the least significant digit wheel of the gas meter index. Whilst this initially showed promise, I found that the rising and falling edges of the pulses were prone to "bounce" which caused false triggering of the pulse counter. I have subsequently replaced the opto-sensor with a Hall Effect magnetic sensor - because the same reflective zero also contains a small magnet, intended to trigger Hall sensors or reed relays.