Thursday, 16 April 2015

Pi Science Project: Tank Power - Part 1 - Outline of project

New Project: Tank Power


To establish whether, in the summer, I should heat my hot water tank using electricity via the immersion heater or use gas via the central heating boiler. 

Hypothesis: Electricity is a more efficient way to heat the water in the tank because when using gas, there is heat loss via the pipes transporting the heat from the boiler to the tank and also heat lost from the boiler flue pipe.


Proposed Method:

Use Raspberry Pi and temperature sensor to log the temperature of the tank by fitting the sensor to the outside of the tank. Record the value every 2 minutes. By looking for when the temperature is rising, the length of time for which energy is being supplied to the tank each day can be measured. 

For gas heating, if the quantity of gas used during the same 24hr period is known, the energy consumption can be calculated. 

For electrical heating, if the power consumption of the the heater is known then the energy consumption can be calculated.

Other factors should be revealed, for example the rate of heating for gas compared to electricity and how well the thermostats work at regulating the temperature.

Step 1: Rig up the pi logging the temperature of the tank with the sensor taped to the outside to gather preliminary data. 

draft pseudo code:

#import sqlite to write the temperature and time data to a file
#import matplotlib to write the data  to graphs
#import OS  to access the temperature sensor

#if it doesn't exist create the database
#open the database

#read the current temperature and time

#write time and temp to the end of db

#get the data from the db (how much?)

#1) last 24 hours
#2) last 6 hours
#3) last 3 hours

#plot each graph to a .png for showing on a database

#data analysis extension:
#import last 24 hours data (midnight to midnight)
#read temperature values
#if temperature is rising start the timer
#if temperature is falling stop the timer
#might need to average these values out to allow for small fluctuations
#add the timer value to total 'on' time
#return a value for total time of rising temperature in 24 hrs
#calculate the theoretical value of energy used vs actual?
#for electrical this is easier done by the program if the power rating of the heater is known
#for gas would need to input the meter reading for the 24hour period and do some calcs.


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