Hi all, its been a while since I last stretched the brain and this latest project is certainly going to do that.
I have recently acquired a diesel/water pre heater off a mazda car and am planning to use this to heat my shed and the green house, the only problem is that it will not run stand alone with out the ecu on the car. My idea is to build my own controller using a PICAXE 18A. I have listed below how far I’ve got in the sense of I/O.
' Diesel Heater Control
' PICAXE-18A
' INPUTs
' symbol temp sensor = pin0
' symbol flame sensor = pin1
' symbol standby/run = pin2
' symbol lock out reset = pin3
' OUTPUTs
' symbol lock out LED = 0
' symbol burner motor = 1
' symbol fuel pump = 2
' symbol water pump = 3
' symbol glow plug = 4
The temp and flame sensor are analog (which is new to me) and the other to inputs are straight digital on/off. All of the outputs are on/off but I would like the burner motor to be speed adjustable in order to do high and low flame running at certain temperatures, also the fuel pump is a metering type and needs to be pulsed about two or three times a second for high flame and once a seconds for a low flame along with the slower burner motor speed. (still with me).
The idea of operation is hopefully as follows :-
1. pin2 high (system run)
2. water pump on
3. burner motor on full for a few seconds then slow to half and stop
4. glow plug on
5. after 10sec, one pulls of fuel pump and burner motor on half
6. after 4sec another pulls of fuel
7. after 4sec another pulls of fuel
8. after 4sec another pulls of fuel
9. after 4sec another pulls of fuel
10. check input from flame sensor
11. if ok (flame lit) then increase fuel to three pulses a second and the burner motor to three quarters. If not (flame out) switch off glow plug and fuel pump and run burner motor at full for 10sec and lock out.
12. if still ok switch off glow plug and continue to run.
When the burner is up and running and happy then the temperature control comes into play. I would like it so that from the minimum temp to about 60C the burner ran at full power (high flame) and then from then to 75C run at half power (low flame). When the temp reaches 75-76C the burner should shut down as follows but leave the water pump running :-
1. fuel off
2. continue to run burner motor for 30sec
3. stop burner fan and standby
when the temperature drops to about 70C restart.
When it is time to shut down fully the following should happen :-
1. fuel off
2. continue to run burner motor and water pump for 30secs
3. stop burner and water pump motor
4. standby
I hope that all sort of makes sense and welcome any suggestions.
I have recently acquired a diesel/water pre heater off a mazda car and am planning to use this to heat my shed and the green house, the only problem is that it will not run stand alone with out the ecu on the car. My idea is to build my own controller using a PICAXE 18A. I have listed below how far I’ve got in the sense of I/O.
' Diesel Heater Control
' PICAXE-18A
' INPUTs
' symbol temp sensor = pin0
' symbol flame sensor = pin1
' symbol standby/run = pin2
' symbol lock out reset = pin3
' OUTPUTs
' symbol lock out LED = 0
' symbol burner motor = 1
' symbol fuel pump = 2
' symbol water pump = 3
' symbol glow plug = 4
The temp and flame sensor are analog (which is new to me) and the other to inputs are straight digital on/off. All of the outputs are on/off but I would like the burner motor to be speed adjustable in order to do high and low flame running at certain temperatures, also the fuel pump is a metering type and needs to be pulsed about two or three times a second for high flame and once a seconds for a low flame along with the slower burner motor speed. (still with me).
The idea of operation is hopefully as follows :-
1. pin2 high (system run)
2. water pump on
3. burner motor on full for a few seconds then slow to half and stop
4. glow plug on
5. after 10sec, one pulls of fuel pump and burner motor on half
6. after 4sec another pulls of fuel
7. after 4sec another pulls of fuel
8. after 4sec another pulls of fuel
9. after 4sec another pulls of fuel
10. check input from flame sensor
11. if ok (flame lit) then increase fuel to three pulses a second and the burner motor to three quarters. If not (flame out) switch off glow plug and fuel pump and run burner motor at full for 10sec and lock out.
12. if still ok switch off glow plug and continue to run.
When the burner is up and running and happy then the temperature control comes into play. I would like it so that from the minimum temp to about 60C the burner ran at full power (high flame) and then from then to 75C run at half power (low flame). When the temp reaches 75-76C the burner should shut down as follows but leave the water pump running :-
1. fuel off
2. continue to run burner motor for 30sec
3. stop burner fan and standby
when the temperature drops to about 70C restart.
When it is time to shut down fully the following should happen :-
1. fuel off
2. continue to run burner motor and water pump for 30secs
3. stop burner and water pump motor
4. standby
I hope that all sort of makes sense and welcome any suggestions.