Solar Hot Water systems

The Merus ring will only treat the water that runs through it. So placing a ring on the cold mains service pipe into the house, will treat all the water used in the house excluding the water in a closed system.
 
To treat the water in a closed system, the ring needs to be placed on the closed system itself.
 
One other consideration is that some closed systems may have a heat transfer fluid or antifreez liquid instead of water. Merus works in water systems only.
Related links
 
Closed System
solar hot water.
 
If it's a closed system then the hot tap water is different to the water heated from the sun and has been heated through a heat exchanger.
 
The solar heated water circulating through a heat exchanger Heats the tap water "indirectly".
 

2 Merus Rings Required

For maximum protection
 
 
Place one ring on the closed system, before the pump. Place the 2nd ring on the cold water main into the house.
Open Systemsolar panel.
If the system is an open system, the water heated from the sun is the same hot water as the hot water at the taps in the house.
 
...The solar hot water is heated "directly" from the sun. ..
 
 
 

1 Merus Ring is Required

For maximum protection
 
Place the Merus ring on the cold water main into the house.