What's the major/minor difference between the (4390-1) & (4390-2) 13-15kw and the older 6-7kw and 12kw units with the same 1 or 2 at the end of the model numbers? Thanks, Bodine
Geoff Z
I believe the fuel pressure switched between the 1 and the 2 going from a required high pressure inlet (11-14" W.C. NG) to normal house pressure of 5-7" W.C.

Back in the day we had to have an elevated gas meter installed for every generator job we did.