• Hold the two hoses leading into the pail with one hand – it is vital that the ends remain as close to the bottom as possible. You can use spring-loaded clamps attached to the edge of the pail to hold them in place if you prefer.
• Switch on the pump. Never leave the hoses or pump unattended while they are in operation. If you're holding the hoses in your hand, do not let them go as long as the pump is running.

Assuming everything goes normally, the level of solar fluid in the pail will start to drop and air will come out of the outlet tube, causing bubbles. You will also hear odd gurgling and bubbling noises, which are normal. Keep an eye on the pressure gauge – you want it to stay between 10 and 25lbs/in², which you can control by adjusting the inlet or outlet filler valve. Top up the charging pail as required, always trying to keep it half full, and keep the empty containers nearby in case you need them.

Once the system is almost full, the air coming out of the system will almost stop and the pressure will try to rise. Adjust the valves to maintain a reasonably constant pressure in the 10-25lbs/in² range.