Increase up/down limit range from 10 to 15 degrees

Our public use hall has long periods without any heating as the hall is not in use, at these times the temperature in the hall during the winter can drop close to ambient as the heating is not on at all. We’d like the base temperature to be programmed at 5 degrees, but doing this means we can’t use the up/down limit feature as this would then prevent the temperature being set above 15 degrees (the current maximum limit is 10 degrees away from the base temperature.). Increasing ten range on the up/down limit to 15 degrees would address this problem without any real downside.