So I purchased a tax credit eligible stove,( Englander NC30) but am confused on the eff rateing of the stove. The paper that came with the stove showed it as around 63% eff but the tax credit needs 75% with “lower heating value” . What does lower heating value mean? Is the stove 63% eff when running full tilt and better when not run as hard? I also noticed this when looking at stove spec, one place would say 85% eff and the stove manual would say 63%.for the say stove. Confused.........