Been asking around for bits for a DIY solar panel and on three occasions now retailers have sucked their teeth and muttered "Ooooh.... Legionnaire's disease!" at me. WTF is this paranoia?
Let's start with the primary (panel to coil) circuit: how is a bacterium supposed to enter then grow in a closed system containing ethylene glycol and antioxidant and sometimes being heated to 80 or 90 degrees C? In any case this system is completely separated from the storage cylinder.
Next, the storage cylinder: this is fed with treated water from the header tank and the family draws off water every day, probably replacing the entire contents of the cylinder a couple of times a day with fresh. The cylinder is closed and the water heated to 60 degrees C so how is a legionnaire's bacterium supposed to get into it then grow?
Next, the most stupid part of the argument: the pipework and shower head downstream of the cylinder: of all the millions of households where showers are in regular or even irregular use, has there ever been a proven case of a householder catching Legionnaire's from the shower? And why would solar heated water increase the risk if such a risk existed?
Even assuming you go away for two weeks and leave tepid water at 20-30 degrees C in the cylinder, at which temperature bacteria could possibly thrive, how does the Legionnaire bug get in? Has there ever been a case of somebody getting back from holiday, taking a cool shower then catching Legionnaire's?
As far as I can see this is another myth being pedalled by the emerging solar industry to prevent enthusiastic householders and DIYers from building then installing simple systems at a fraction of the cost of their off-the-shelf systems. And from some of the systems I've seen sold to gullible householders, I can quite understand why this "industry" would want to protect its profits.
Let's start with the primary (panel to coil) circuit: how is a bacterium supposed to enter then grow in a closed system containing ethylene glycol and antioxidant and sometimes being heated to 80 or 90 degrees C? In any case this system is completely separated from the storage cylinder.
Next, the storage cylinder: this is fed with treated water from the header tank and the family draws off water every day, probably replacing the entire contents of the cylinder a couple of times a day with fresh. The cylinder is closed and the water heated to 60 degrees C so how is a legionnaire's bacterium supposed to get into it then grow?
Next, the most stupid part of the argument: the pipework and shower head downstream of the cylinder: of all the millions of households where showers are in regular or even irregular use, has there ever been a proven case of a householder catching Legionnaire's from the shower? And why would solar heated water increase the risk if such a risk existed?
Even assuming you go away for two weeks and leave tepid water at 20-30 degrees C in the cylinder, at which temperature bacteria could possibly thrive, how does the Legionnaire bug get in? Has there ever been a case of somebody getting back from holiday, taking a cool shower then catching Legionnaire's?
As far as I can see this is another myth being pedalled by the emerging solar industry to prevent enthusiastic householders and DIYers from building then installing simple systems at a fraction of the cost of their off-the-shelf systems. And from some of the systems I've seen sold to gullible householders, I can quite understand why this "industry" would want to protect its profits.
