(Effective July 1, 2023)

PDFWAC 51-11C-403326

Table C403.3.2(6)Minimum efficiency requirementsGas-fired and oil-fired boilers.

Table C403.3.2(6)
Gas- and Oil-Fired BoilersMinimum Efficiency Requirements
Equipment Typea
Subcategory or Rating Condition
Size Category (Input)
Minimum Efficiency
Test Procedurea
Boilers, hot water
Gas-fired
< 300,000 Btu/hg,h for applications outside
the U.S.
82% AFUE
DOE 10 C.F.R. 430 Appendix N
≥ 300,000 Btu/h and
≤ 2,500,000 Btu/he
84% Etd
DOE 10 C.F.R. 431.86
> 2,500,000 Btu/h and
≤ 10,000,000 Btu/hb
85% Etd
> 10,000,000 Btu/hb
82% Ecc
Oil-firedf
< 300,000 Btu/hg,h
84% AFUE
DOE 10 C.F.R. 430 Appendix N
≥ 300,000 Btu/h and
≤ 2,500,000 Btu/he
87% Etd
DOE 10 C.F.R. 431.86
> 2,500,000 Btu/hb
88% Ecc
> 10,000,000 Btu/hb
84% Ecd
Boilers, steam
Gas-fired
< 300,000 Btu/hg
81% AFUE
DOE 10 C.F.R. 430 Appendix N
Gas-fired - all, except natural draft
≥ 300,000 Btu/h and
≤ 2,500,000 Btu/hb
82% Etd
DOE 10 C.F.R. 431.86
> 2,500,000 Btu/ha
79% Etd
> 10,000,000 Btu/hb
79% Etd
Gas-fired - natural draft
≥ 300,000 Btu/h and
≤ 2,500,000 Btu/hb
81% Etd
> 2,500,000 Btu/hb
82% Etd
> 10,000,000 Btu/hb
79% Etd
Oil-firedf
< 300,000 Btu/h
82% AFUE
DOE 10 C.F.R. 430 Appendix N
≥ 300,000 Btu/h and
≤ 2,500,000 Btu/hb
84% Etd
DOE 10 C.F.R. 431.86
> 2,500,000 Btu/hb
85% Etd
> 10,000,000 Btu/hb
81% Etd
For SI: 1 British thermal unit per hour = 0.2931 W.
 
a
Chapter 6 contains a complete specification of the referenced standards, which include test procedures, including the reference year version of the test procedure.
 
b
These requirements apply to boilers with rated input of 8,000,000 Btu/h or less that are not packaged boilers and to all packaged boilers. Minimum efficiency requirements for boilers cover all capacities of packaged boilers.
 
c
Ec
=
Combustion efficiency (100 percent less flue losses).
 
d
Et
=
Thermal efficiency.
 
e
Maximum capacity – Minimum and maximum ratings as provided for and allowed by the unit's controls.
 
f
Includes oil-fired (residual).
 
g
Boilers shall not be equipped with a constant burning pilot light.
 
h
A boiler not equipped with a tankless domestic water heating coil shall be equipped with an automatic means for adjusting the temperature of the water such that an incremental change in inferred heat load produces a corresponding incremental change in the temperature of the water supplied.
 
i
This table is a replica of ASHRAE 90.1 Table 6.8.1-6 Gas- and Oil-Fired Boilers—Minimum Efficiency Requirements.
[Statutory Authority: RCW 19.27A.020, 19.27A.025, 19.27A.160 and chapters 19.27A and 19.27 RCW. WSR 22-14-091, § 51-11C-403326, filed 7/1/22, effective 7/1/23.]