I got an answer to your question from Abe Stallcup, P.E. of Monterey Energy Group.
"Assuming your thermo siphon is sized to meet your domestic hot water demand you will not be able to effectively use this existing system for radiant heating.
- You would need to add additional solar thermal panels to the system as well as additional pumping components and controls.
- Combination solar thermal systems that provide both domestic water heating and space heating can be complex and expensive to retrofit in an existing condition.
Many companies are producing packages that incorporate all the elements but will depend on many factors with your current system. Factors must be considered such as:
- panel space,
- additional mechanical room space,
- additional storage tanks,
- summer heat "dump", etc.
In addition to solar hot water, there are options to use solar PV and utilize efficient air to water heat pumps to produce hot water. These system provide an opportunity to use PV net metering and solve a lot of the complexities of solar thermal."
For more information:
- Which is Better: Solar Thermal Flat Plate or Evacuated Tube Collectors?
- Solar Thermal is Dead
- HTP solar flat plate collectors
- HTP Versa-Hydro
- Solar Skies solar collectors
- Daikin Altherma
Polly Osborne, AIA