Gas hot water heater with high R-value insulation
I have located 2 gas hot water heaters (a Kenmore Power Miser 12 & a Bradford White M4) with 2" insulation. The Kenmore specs say that the 2" insulation has an R value of 16 (R16).
Does anyone know of a manufacturer that offers even more insulation (i.e. more than 2 inches or an R value higher than 16)?
Many thanks. And please, no responses saying I should go "tankless"--it's not cost effective to retrofit--I've looked into it, believe me.