I am working with a pal on a harman pellet boiler. Just getting it to run after installation in series with an existing oil fired boiler. 1- the harman set at 165 degree water temp still feeds pellets at 175+ degrees water temp. It will stop if you turn feed rate down to 1 and turn hi temp down to say 140 degrees.(not using outside temp reset) Q- is there a time frame ,that makes the stove stop slowly, programmed in? or do I have a dip-switch not right on control board or perhaps an aquastat sensor problem 2- the circulator, water makeup/feed, expansion tank, and such are at the original oil fired boiler, which are at a 2 foot higher level than Harman PB and approx. 15 foot of piping away . (in a different room) What is happening at startup of PB is the water pressure reads 20 pounds and by the time it gets to 180 degrees it is just shy of 30 pounds and once opened pressure relief. These readings are from top gage on harman PB. meanwhile at the other boiler, near the expansion tank, it reads just a bit over 20 pounds there. Q- do i have an air pocket giving this problem, or do I need a bigger (or an additional) expansion tank near PB. Or is the expansion tank now too small for the added water of both boilers? It makes no sense why the pressure is different at both boilers.( Assumption they are both good working gages). All the piping is connected in series.