This is our first house with a boiler and I have a question about the most efficient way to use it. We have multiple zones and it seems like heating one zone while not heating others might degrade the efficiency. For instance, if the bedrooms are being heated but the living room/kitchen isn't (but they're still colder than we would want if we were up) are we losing efficiency by not letting both zones heat at the same time while the boiler is running to heat the bedrooms?