I have been getting quotes for a new oil boiler. One company recommended an "Indirect Storage Tank" and said it would save us $300/yr in oil costs. The estimate for the installation was about $6000, the biggest estimate I've received. He went on to say that all boilers, in a few years, will have this because the gov't is going to regulate this due to the oil efficiency potential. Is this stuff true? If we decide not to get the indirect storage tank now, can we convert to it or add it on later? If so, is the cost high?