Bradford White RG2D40S6N (40 gal) vs RG2D50S6N (50 gal) damper tanks

An automatic flue damper closes the vent passage while the burner is off, so heated room air and residual tank heat stop flowing up the chimney, and it opens before the burner fires. The sheet credits the design with reduced standby loss, which shows up as UEF 0.68 on the 50-gallon model against 0.63 for the plain atmospheric RG250T6N at the same 40,000 BTU/h input and capacity. That is a real five-point gain under the same medium-draw test.

The two sizes in this family do not follow the usual pattern. The 50-gallon damper tank delivers 81 US gal (307 L) in the first hour, the same figure as the plain 50-gallon RG250T6N, while the 40-gallon damper tank delivers 62 US gal (235 L), well below the plain 40-gallon RG240T6N's 284 L. The 40-gallon damper model is therefore the one case in the line where the damper's benefit in standby comes with a first-hour figure below a plain tank of the same size. Buyers whose constraint is busy-hour delivery, not standby loss, should compare it with the plain atmospheric models before choosing.

Both are Defender Safety System FVIR tanks with the ICON electronic control and no standing pilot. The damper and control run on 120 VAC from an included 10 ft (3 m) power cord, so each needs a receptacle and neither makes hot water during a power outage, unlike the millivolt atmospheric tanks that run on the pilot thermopile. Venting is a 3 in or 4 in draft diverter into a chimney or B-vent, so a sound flue and room combustion air are still required.

Fit and weight separate the pair more than efficiency does. The 40-gallon model stands 47 11/16 in (1211 mm) to the top of the heater in a 22 in jacket and ships at 155 lb; the 50-gallon model stands 56 9/16 in (1437 mm) in the same 22 in jacket and ships at 174 lb, so ceiling height is the practical constraint rather than width. Both carry a 6-year tank and parts warranty with no labour, and both need the anode inspected every two years.