So, this evil boiler we have is an object of contempt for me lately. Our oil tank is almost empty and the thought of spending 600 to 800 dollars to fill it just isn't going to fly right now. How do I keep this thing as efficient as possible? We had it cleaned and serviced last year and the guy said it was pretty dirty. I would like to take some time to clean it but want to know what I should be looking for ahead of time. What's in there? Also, it periodically runs to maintain a supply of hot water right. Is there any way to make it run ONLY when there is a demand for it? It heats the water up almost instantly when it runs, so there wouldn't be any lag time.