EN-05 · 02 Energy
Thermosiphon solar hot water
Collectors below a tank, no pump, no controller — water that rises because it is hot, and a household that still washes when the grid is quiet.
Origin
Early solar-thermal practice; still common in the Mediterranean and Andes
Materials
- A flat-plate or evacuated-tube collector
- An insulated tank mounted above the collector
- Copper or PEX with a continuous rise and no air locks
- A tempering valve at the tap
Method
- 01
Place the tank above the collector. This is the whole trick. A tank below needs a pump, and a pump needs power.
- 02
Keep the loop short, fat and always rising toward the tank. A dip in the pipe will stall the thermosiphon.
- 03
Insulate the tank as if it were a winter jacket. Overnight losses are where most systems fail.
- 04
Fit a mixing valve so the tap cannot scald on a clear noon.
- 05
Drain or recirculate in a hard freeze. A burst collector is a weekend of work.
What this makes possible
- Domestic hot water with no moving parts
- A system a plumber can understand without a software update
- Less biomass or electricity spent on a kettle
This is a field record, not a permit. Adapt to local law, climate and skill. If you have run this method, send what you learned.