When the pump is not running in a drain-back solar system, all of the liquid is inside the building and the solar panels are empty of fluid. A small tank (the drain-back vessel) holds the liquid so. In a pressurised solar system, the solar circuit is completely filled with liquid at all times, including overnight in freezing weather and during periods of stagnation. To prevent burst pipes in the solar panel the circuit is filled with antifreeze solution, around 40% by weight of. A re-start of the solar pump following stagnation will result in steam being pushed out of the solar panel and down the pipes to the cylinder for both drain-back and pressurised systems. The steam quenches rapidly on the cooler pipe-work, but instantaneous.
Solar Supply and Return Piping Installation Making Pipe Connections Solar Supply and Return Piping Basic pipe connections 1. Work out the length of the stainless steel pipe needed. Do not extend line sets beyond 50 ft (15 m). Cut insulation to length and push back out of the way temporarily.
How to arrange plumbing in a solar loop?
There are two main choices for how to arrange the plumbing in the solar loop, drain-back and pressurised solar systems: When the pump is not running in a drain-back solar system, all of the liquid is inside the building and the solar panels are empty of fluid.
To prevent burst pipes in the solar panel the circuit is filled with antifreeze solution, around 40% by weight of propylene glycol will protect the solar panels down to -20C. The volume of the solar fluid will change as its temperature changes, expanding when it heats up and contracting when it cools down.
The propylene glycol antifreeze solutions in liquid (hydronic) solar heating collectors need to be replaced periodically. The pH (acidity) and freeze point of the fluid can be measured with hand-held instruments and replaced if out of specification. It's a task best left to a qualified technician.
Suitable materials for the pipes of the solar circuit offer: the necessary weathering and corrosion resistance for outdoor use (no galvanised pipes). The hot water storage tank should have a volume of 1.5 to 2 times the daily consumption of hot water per person, i.e. about 100 litres per person, to store hot water for days with less radiation.
Push union nut and clamping rings over copper pipe adaptor, and lightly lubricate the threads with oil. - Push the pipe into the compression fitting all the way to the stop. - Initially, turn the union nut manually by hand, then tighten with a flat wrench by another ¾ turn or until snug.