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AO Smith HWH - can heating capacity be increased by changing orifice?
This is a AO Smith 50 gallon power vent unit rated at 40K BTUH operating on LP gas. It's in a very northern climate where the incoming water is bone-chillingly cold. So it takes a very long time for tank recovery - just washing a few dishes by hand kicks off a 30 minute cycle.
Seeing that the unit is rated at 46K BTUH on NG, I assumed that the power vent and PVC could handle a slight increase in flue gas temp.
I was wondering if changing the orifice is an acceptable method of increasing heating capacity? I know that efficiency will drop somewhat. The stock orifice is #48 and I was considering drilling out to a #46 - which should take the capacity up to 45K BTUH.
I'd probably buy a new orifice and drill it out, rather than sacrifice one that is working - just in case. It looks like it's a brass hex 3/8" type - is this a standard orifice or will I need an actual AO Smith part ?