Yah, not a bad idea. But that means you won't be able to use an exchange and will always have to go the refill route. It might suck if you run out in the middle of a cook and the refill stores are all closed. But, if you keep the old 20 lb in reserve, you will be fine. If you don't move the grill around, you could probably go with one of the big 100 lb tanks.