I have the same stove , your description has so many variables in it its hard to say , on your house how well is it insulated and is this your only source of heat ?? a 40x 60 shop is huge , same question , how well insulated and only source of heat ?
I have 2 large greenhouses , 1 30 x 50 14 ft tall , only 2 layers of 6 mil plastic , other is 20 x 50, 10 ft tall and one layer 6 mil , last night it was 15 degrees , both are heated with a 22x22 WTA exchanger, fan and thermostat
when its this cold I get a 5 hour burn time on a full load , I have both greenhouse set at 60 degrees , when its warmer 35-40 degrees I can get a 12 hour burn time ,
what kind of wood and seasoned or not makes all the difference , I can burn some sycamore and i get a lot of white smoke , I burn oak , cherry , hickory i don't see any smoke rather a " wave of air " that is transparent
my stove has 3 separate wilo star21's on it and a port for the 4th , haven't had the first issue with them and in my second year , I'm sure there are others as good or better but at the end of the day it comes down to a lot of opinions , your pump should have 3 speeds on them and tell you the GPM for each setting , you can plumb in a couple T's and put a gauge like this (
http://www.blueridgecompany.com/radiant/hydronic/660/pasco-rht-temperature-gauges) in at the outlet and return outlet to see your temp drop on a line , that will tell you if your loosing heat to the ground or not , see the attached picture
I think a 12 hour time on your stove for a house and large shop of that size depending on how well insulated would not be out of the norms
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