Hello all.

A large 'drinking water' bottle ~20 litres with air; plugged with a hose trough it and two 3mm opposed valves (one intaking / one exhausting) The intention is to pull water from a lower rain cistern during the nights temperature that creates suction; and expelling water during the daytime heat of sun expansion. For drip irrigation purpose.

The bottle hung on a wall, covered with black plastic until soon painted black. The inlet and the outlet valves seen at each side of the 'T' Weather has not collaborated lately with wide daily fluctuations. 2 metres lift is the goal without using solar-electric pump.

Another similar using a half-filled 2 litre bottle is working : pushes its water dripping to the plant when air inside expands heated by sun. Sucks replenishing air when gets colder. also to be painted black. Seems very scalable.

Comments and improvements are welcome.

For 2 metres lift (~20% of atmospheric pressure), wouldn't you need a diurnual absolute temperature swing of ~20%, ie ~60 K.

A bit optimistic for a system without collection mirrors perhaps.

And then there's the problem of vacuum collapse of the vessel. It may have to be located at or below the input liquid level to maintain a positive hoop stress.

Edited 18 hours ago18 hr by sethoflagos

I can't really comment about whether the scheme will work or not but if you are irrigating with the water from that jug, be careful. I lived off grid at around 40 N latitude for a year and my shower was similar except it was a 15 gallon carboy painted black. on a hot sunny day the water would often be so hot that it was necessary to add cold water to keep from being scalded while using it. If there is water actually flowing through it might not be a problem but I would consider it possible that the irrigation water might get too warm if used directly from the jug.