I have a Mits mini split systems rated at 21 seer (2 condensors and 3 "head" units) and was wondering at what outdoor temp does it make sense to go back to oil heat (forced hot water) to save $$ ??? My electric rate is .13 per kw (thru Verde electric) and I can get oil for around 2.30 a gal. The Mits can produce heat down to 0 degrees but I believe its efficiency is poor at those temps. leading to higher electric bills. I live in central Mass. where electricity has gone thru the roof the last month. I also supplement w/ pellet stove usage.