SOL-Perpetua™ Solar Water Heating System Installation Instructions and Operating Manual For Series "A" Pumps
SOL Perpetua™ System Maintenance - Heat Exchanger Cleaning
The heat exchanger on the working fluid side will probably always remain clean. On the potable water side, however, scale may build up. Scale results from dissolved minerals in the potable water coming out of solution. In some localities this will not happen or be only minor and in other areas it is a common problem requiring periodic attention. Scale will lower the efficiency of heat transfer and in severe instances can completely close up the fluid passages.
If you know you have hard water and are not using a water softener it is advisable to clean out the scale every 3 to 6 years with a scale removing fluid such as is used to descale a kettle or steam iron. Disconnect the convective loop (that is, the potable water side) of the Module from the storage tank at the unions, let the water run out, reconnect at bottom but leave bottom isolation valve closed, pour descaling fluid in at top union, let stand overnight, disconnect at lower union, let fluid drain out, flush out by pouring in water at the top union, reconnect both top and bottom unions and open both top and bottom isolation valves.
You might at the same time flush out your storage tank and change the working fluid of the solar collector system. You may be surprised what comes out at the bottom of a hot water tank.