There are three steps to the charging process. Make sure you read and understand all three stages before starting the charging process.
- Pumping the solar fluid in.
- Getting the air out (this page).
- Pressurizing the system.
CAUTION: You must cover the solar collectors when charging the system! Uncovered collectors will heat the fluid to extremely high temperatures which can cause steam venting and serious injury.
This is not optional: protect yourself. Cover the collectors.
Check for leaks
While you're getting air out of the system, you should also check for leaks. If you have someone working with you, get them to walk the pipe run, checking every join and connection. If you are on your own, you can pump fluid into the system until the pressure is between 25 and 40lbs/in², close both valves, switch off the pump and walk the loop yourself.
Be very careful with the loop pressure. If you switch off a little early and need to bump the pressure up a bit, make sure you open the filler valve a tiny bit and build up slowly. Assuming you find no leaks, you can continue pushing the air out of the system.
Getting the air out of the system
When you start to pump solar fluid into your solar loop, air is pushed out into the charging pail, causing lots of bubbles. If you do not see air bubbles in the charging pail and the pressure keeps rising, you have a blockage. Switch off the pump before the pressure goes over 50lbs/in² and be careful of the backwash of fluid to the pail from the pump.
- Check that all the ball valves in the system are open.
- Check that the pipe run from the inlet up to the collectors, down to the heat exchanger and to the outlet port has no problems.
- If all the valves are open and the plumbing is solid, you may have an air lock.
Air locks can be dislodged by closing the inlet valve (leave the drain valve open). Turn on the pump and slowly open the inlet valve a crack – the pressure will slowly rise. Make sure you leave the drain valve open and keep a firm hold on the hoses in the pail. Allow the system to hit 60lbs/in², then shut off the inlet valve and switch off the pump. This is usually enough to dislodge a lock.
If that doesn't work, try closing and opening all the ball valves, which sometimes trap air. If that doesn't work, the last resort is to push the pressure up to 75lbs/in². Never go above this pressure level.
Finishing up
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.
It is very important to keep the charging pail at least half full at this point. You will also need plenty of light to see what's happening in that pail. It's safe to shut off the pump and