I turned the central heating on tonight for the first time since the Spring but the towel rail in my bathroom won't heat up. I must have turned the rail off a couple of weeks ago, when I attempted to add inhibitor. After trying to follow an online video on how to add inhibitor I gave up and thought I'd reversed the actions but I've clearly missed something as it now won't heat up. I'm sure it's just one simple step I've overlooked. Can anyone help?Thanks.