Children did some reseaech of how they could reduce CO2 in the school and help the boiler run more efficiently. They found endotherm which reduces energy cost and consumption by a minimum of 15%. The chemical was put in the system today and will last 5 years. The chemical turns into a foam which goes into the pipe work which then allows the gas to run freely and better. This was explained by the engineer to the children. https://www.endotherm.co.uk/