Difference between revisions of "Temperature Difference Sensor and Switch for Solar Water Circulation Pump"
m (typo) |
(grammar improved) |
||
| Line 6: | Line 6: | ||
[[File:Water_temp_difference_sensor_and-on-off-switch_for_solar-pump.jpg]] | [[File:Water_temp_difference_sensor_and-on-off-switch_for_solar-pump.jpg]] | ||
| − | + | The copper pipes transfer temperature changes with a lag and the volume of flow is small so the off/on power cycling to the pump is less frequent than you might surmise. | |
| − | Also, my pump can run without harm | + | Also, my pump can run without harm at low voltages, and variable speed. So a sharp slope in the voltage changes by size of temperature difference is not needed for my pump. |
| − | is not needed for my pump. | ||
| − | 2025: I wanted a steeper slope | + | 2025: I wanted a steeper slope of voltage changes for instantaneous off/on so I added a pre-amplifier: |
[[File:water_temp_difference_preamp_NoRelay.png]] | [[File:water_temp_difference_preamp_NoRelay.png]] | ||
Alternative configuration with a relay: [[File:Water_temp_difference_sensor_and-on-off-switch_for_solar-pump_relay.png|200px|thumb|left|relay version]] | Alternative configuration with a relay: [[File:Water_temp_difference_sensor_and-on-off-switch_for_solar-pump_relay.png|200px|thumb|left|relay version]] | ||
Latest revision as of 16:24, 27 May 2025
ALL MY PROJECTS ARE HERE: https://opencircuits.com/index.php?title=User:Definitionofis
This is using two diodes to sense the temperature of the roof solar collector and the storage tank in the house. The diodes form a H-bridge which drifts +- through to -+ across the op amp inputs, depending on the temperature difference which varies the diodes' forward resistance. I have been running this for seventeen years with the diode on the roof touching the hot water outlet pipe.
The copper pipes transfer temperature changes with a lag and the volume of flow is small so the off/on power cycling to the pump is less frequent than you might surmise. Also, my pump can run without harm at low voltages, and variable speed. So a sharp slope in the voltage changes by size of temperature difference is not needed for my pump.
2025: I wanted a steeper slope of voltage changes for instantaneous off/on so I added a pre-amplifier:
Alternative configuration with a relay:
