I recently went on a site visit to an installation of a Woodfire RSD15 inset stove which we supplied. As part of the visit I deliberately overheated the system and turned off the load unit pump. This meant that the only heat leaving the system was via the heat leak radiator. I was pleased to say that the installers had done a great job; the heat leak radiator worked a treat with no boiling over in the system. Even if there had been they had used one of our high temperature header tanks so it would not have melted it, but of course you want to avoid boiling if possible. As you can see I had it fired up nice and hot!