Why sell a "blanketed" gas water heater?

Jells

I recently ordered and installed an AO Smith "40 Gallon - 40,000 BTU ProLine Blanketed Residential Gas Water Heater - Tall Model (Nat Gas)". It was one of the few 18" dia I found, larger would not fit the space. In the box came a tightly rolled insulation blanket!

Am I correct in guessing that this is simply a way of making an older model heater comply with current efficiency standards to be able to sell it? I'm assuming the heater is no more or less efficient than the 12 year old nearly identical dimension Rheem it replaced.

I'm dubious about the efficacy of the blanket, in my mind way more of the standby losses go up the flue pipe than out the jacket.

hot_rod

The jacket loss depends on how cold the room where the tank is located gets. There is a formula for that calculation in one of the Idronics. If your chimney has a high draft, no doubt that is a big loss number

I think you are correct that an 18” diameter tank may not meet the energy standard without a R3-5 blanket

Jells

hot_rod said:

The jacket loss depends on how cold the room where the tank is located gets. There is a formula for that calculation in one of the Idronics. If your chimney has a high draft, no doubt that is a big loss number

I think you are correct that an 18” diameter tank may not meet the energy standard without a R3-5 blanket

It's in a heated room so not so cold. It's funny if it's one of those "fig leaf" regulatory compliance things, like the safety clip on a lighter everybody pulls off, or the blade guard on a table saw that never gets installed.