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Comparison
Verdict in brief
A. O. Smith Burkay HW-300 and A. O. Smith Burkay HW-399 are two non-condensing boilers from the A. O. Smith Conservationist Burkay (hot-water boilers) line. The A. O. Smith Burkay HW-300 is rated 300,000 BTU/h natural and propane input, and the A. O. Smith Burkay HW-399 is rated 399,000 BTU/h natural and propane input. A. O. Smith Burkay HW-399 lists 99,000 more input than A. O. Smith Burkay HW-300 (399,000 against 300,000). A. O. Smith Burkay HW-399 lists 51 lb more shipping weight than A. O. Smith Burkay HW-300 (301 lb against 250 lb).
Published manufacturer figures. Input and output are kept separate; blanks mean the manufacturer did not publish that value.
| Specification | A. O. Smith Burkay HW-300 | A. O. Smith Burkay HW-399 |
|---|---|---|
| Input rating | 300,000 BTU/h natural and propane | 399,000 BTU/h natural and propane |
| Approximate shipping weight | 250 lb | 301 lb |
| Water inlet / outlet | 1-1/4" NPT inlet / 1-1/4" NPT outlet | 1-1/2" NPT inlet / 1-1/2" NPT outlet |
| Gas inlet | 3/4" NPT | 3/4" NPT |
| Fuel | Natural gas or propane (LP) | Natural gas or propane (LP) |
| Draft diverter outlet diameter | 8 in | 10 in |
| Recovery capacity (as printed) | 1,455 GPH at 20 °F rise (natural gas) | 1,935 GPH at 20 °F rise (natural gas) |
| Working pressure | 160 psi, ASME tested and certified | 160 psi, ASME tested and certified |
Published ratings: the A. O. Smith Burkay HW-300 is rated 300,000 BTU/h natural and propane input; the A. O. Smith Burkay HW-399 is rated 399,000 BTU/h natural and propane input. A. O. Smith Burkay HW-399 lists 99,000 more input than A. O. Smith Burkay HW-300 (399,000 against 300,000).
A. O. Smith Burkay HW-399 lists 51 lb more shipping weight than A. O. Smith Burkay HW-300 (301 lb against 250 lb). The water connections differs: the A. O. Smith Burkay HW-300 lists 1-1/4" NPT inlet / 1-1/4" NPT outlet, while the A. O. Smith Burkay HW-399 lists 1-1/2" NPT inlet / 1-1/2" NPT outlet. The draft diverter outlet diameter differs: the A. O. Smith Burkay HW-300 lists 8 in, while the A. O. Smith Burkay HW-399 lists 10 in. The recovery capacity differs: the A. O. Smith Burkay HW-300 lists 1,455 GPH at 20 °F rise (natural gas), while the A. O. Smith Burkay HW-399 lists 1,935 GPH at 20 °F rise (natural gas).
Both records print the same gas connection (3/4" NPT), fuel (Natural gas or propane (LP)) and working pressure (160 psi, ASME tested and certified), per the cited sources.
A. O. Smith
The A. O. Smith Burkay HW-300 is a commercial gas-fired copper hot water boiler rated 300,000 BTU/h input, with 1-1/4" NPT water connections and a 3/4" NPT gas connection.
A. O. Smith
The A. O. Smith Burkay HW-399 is a commercial gas-fired copper hot water boiler rated 399,000 BTU/h input and 319,200 BTU/h output, with 1-1/2" NPT water connections and a 3/4" NPT gas connection.
The A. O. Smith Burkay HW-399 lists 399,000 BTU/h natural and propane, against 300,000 BTU/h natural and propane on the A. O. Smith Burkay HW-300, per the cited documentation.
It ships at 301 lb against 250 lb for the A. O. Smith Burkay HW-300, per the cited sources.
A consultation includes a heat-loss review so the size is right the first time.
On-site service in Greater Vancouver, BC. ROMA lists “Open 7 days” on its site; call to confirm same-day availability.
Sources and verification
Facts checked September 9, 2026. Last updated September 9, 2026. Technical reviewer: not yet assigned.