I have been poking around here for a while as i researched my boiler options and finally decided to join. Great Site! I finally have my solo 40 (scantec) operational this week. My father-in-law and i did all the plumbing. it is plumbed as an only boiler design and i turm off my propoane boiler and valve it out. My first question is does the c-3 circulator run constantly when boiler gets above 165. this seems like a waste of energy. My heat zones are controlled with circulators wouldn't they do the same thing? the boiler is basically hooked up the way it is shown in the manual with thermovar valve and circulator.