SOL-Perpetua™ Solar Water Heating System Installation Instructions and Operating Manual For Series "A" Pumps
Installation - Filling the System
Filling the system should not be attempted when the collector panel(s) are hot. If you cannot schedule filling the system early or late in the day or on a cloudy day, cover the panels with an opaque tarp. Failure to do so can result in live steam and hot fluid issuing when you use the hand vacuum pump and causing burns. Beside this danger, successful filling would be difficult.
The hand pump can develop a vacuum of about 20" Hg (68 kPa) which corresponds to about 20 feet of water (6.1m) at sea level. This means that if you attach a tube to the hand pump and lower the other end of the tube down into a container of water 20 feet (6.1m) below the hand pump, you will be able to draw water from the container up into the hand pump. In filling the system we use this ability of the hand pump to pull water upwards (stated more correctly, we lower the air pressure in the hand pump thus allowing outside air pressure to push water up into the system).
At the lower end of the bubble pump are two drain cocks which serve to set the amount of fluid in the system. We call these the "level set" cocks. Attach a flexible tube to the level set cock on the pipe which brings cold fluid from the heat exchanger into the pump. We shall call this the "'fill tube". Insert the free end of the tube in a container, preferably one large enough to hold the entire fluid inventory. The container should be tied down to prevent it from falling off the roof.
Open the level set cock at the fill tube. Shut the other level set cock. Slip the hand pump over the mushroom valve and pump it. Air will be drawn out of the condenser, that is, the lower part of the bubble pump through the glass tube which ends just under the diaphragm which divides the condenser from the separator. Fluid will rise up the fill tube into the pump and flow down into the collector panel and into the heat exchanger.
As the system begins to fill, bubbles will be seen rising through the fluid in the pump. Wait for these bubbles to gather in the condenser where you can suck them out with the hand pump. When you think you have filled the system to the bottom of the bubble pump, that is, to the level of the two copper tubes at the bottom of the condenser, shut the level set cock to which the fill tube is attached and continue pumping out air with the hand pump until the gauge reads 20 to 25. This vacuum will bring out much of the air that is normally dissolved in the fluid. Allow more fluid in if necessary to bring the fluid level again to the bottom of the bubble pump. Disconnect fill tube. Open both level set cocks one at a time and catch fluid that comes out. The fluid level in the system should now be correct.
If you are a solar heating contractor and have a fluid pressure pump you may want to inject the working through the drain valve at the storage tank. Be sure to have the level set cocks open if you do this as the glass bubble pump is not designed to take high pressure. When fluid issues from the level set cocks, slow the filling process, close the level set cocks and allow air to exit through the mushroom valve until the bubble pump begins to fill. Cease filling with fluid. Place hand pump over the mushroom valve and create a vacuum. Allow air bubbles to come to the surface and admit more fluid as required. Open level set cocks to allow fluid out and establish vacuum as described above.
If you have an electrically powered vacuum pump, a better method than pumping fluid in from the bottom as described above is to first evacuate as much air as possible from the system and then admit fluid at the drain cock. Top up the system as described above.
You are now ready for the sun, provided, of course, that you don't have a leak in the system. If the gauge indicates a fall of vacuum, you'll know that there is a leak in your system. (Refer to TROUBLE SHOOTING).