Richard Weir
Hi JT, If you have the manual you could check out this behavior in the book or down load the manual from freeboilermanuals.com. You may have it set up on a program where it is always providing pre heating to your hot water, in some boiler you have an ECO mode which you have to select to stop it doing this. Failing all of the above I would find an oil boiler expert to take a look at it, post the problem on Rated People.
