Relatives of mine have a huge house (8,000 sft?) that is very well insulated but uses oil heat distributed via radiant flooring. They use approximately 2,000 gallons of oil a year. They have asked me what they should switch too. They have ductwork for a/c. Sorry I don't know the size of the boiler they have, but figure it to be very large. They are leaning to geothermal (at a cost of $40k). Geothermal guy is going to abandon the radiant flooring in place and use the a/c ductwork for heat also. Is he misleading them? Why can't geothermal do radiant flooring? What about a pellet boiler? Do they exist at such a large capacity? I assume you could continue to use the radiant flooring right? If they wanted to store pellets in a silo, how big of one does it need to be? They have two oil tanks inside now, can the silo fit in the place of the oil tanks? Can you get the large bags (one ton) of pellets in Eastern Pa?