I'm told the inhibitor that is put in header tanks is also anit freeze. However you c/h probably is combi boiler so check with c/h supplier or if the conventional type home heating system add your question to home heating further up the forum.
Bob
January 2011
Automatic Answer
We may have found other answers which could help you.
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix caravans/motorhomes.