Solar Water Controller Version 0.01

 

Design

This is the "First Cut" design - using only one temperature probe.

This design is based on the temperature logger. The hardware changes is the removal the RTS / CTS interface and replacing it  with a pump  relay driver.

The PIC code changes are minimal, and still provides serial logging data.

Conclusion

For:

Rapid prototype

Very useful to have a controller that on relies on one probe for a fast installation

Adequate amount of  hot water is collected in the cylinder.

Against:

Some what disappointing  to see the heat draining from the hot water cylinder during the evening! The pump runs warm water through the solar panel, heating up the atmosphere. The lower coil temperature would drop to 30C, before the pump finally stopping. There is about a -1C differential across the coil during this period. Thanks to stratification, the upper part of the cylinder retained the heat collected during the day.

There will be no further work on this single probe design - the three probe design will be the focus for future design effort. (Maybe the advanced design reverts to this simple logic if only one probe is installed...) 

This page was last updated on the 17th January 2002.