We currently have a Glow Worm Flexicom 15hx boiler fitted to a fully pumped heating and hot water s-plan system. The hot water cylinder is a 150 litre open vented cylinder and I looking to replace the cylinder with an indirect unvented 150 litre cylinder (OSO Slimline Indirect RI150-see attached), and wanted to check that the existing boiler is suitable for this upgrade.