Canada-wide gas boiler information · On-site service in Greater Vancouver, BC
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Comparison
Verdict in brief
The EFW-340WBN and EFW-399WBN are the two largest EFW models and share the same cabinet, 4 in. venting to 100 ft, 1-1/2 in. male water connections, 3/4 in. gas, 250 lb operating weight and 95.4% printed thermal efficiency. The 399 simply lifts the input ceiling from 340,000 to 399,000 BTU/hr, heating capacity from 324 to 380 MBH and net AHRI rating from 282 to 330 MBH, while both carry the same 39.9 MBH minimum fire.
Published manufacturer figures. Input and output are kept separate; blanks mean the manufacturer did not publish that value.
| Specification | HTP EFW-340WBN | HTP EFW-399WBN |
|---|---|---|
| Input rate, minimum | 39.9 MBH | 39.9 MBH |
| Input rate, maximum | 340 MBH | 399 MBH |
| Heating capacity | 324 MBH | 380 MBH |
| Net AHRI rating, water | 282 MBH | 330 MBH |
| Water connections | 1-1/2" NPT male | 1-1/2" NPT male |
| Gas connection | 3/4" NPT male | 3/4" NPT male |
| Vent/air intake pipe diameter | 4" | 4" |
| Cabinet (H x W x D) | 36-5/8" x 25-1/4" x 20" | 36-5/8" x 25-1/4" x 20" |
| Approximate boiler weight with water | 250 lb | 250 lb |
| Boiler water content | 7.1 gal | 6.4 gal |
| Control | Advanced Honeywell Sola boiler controller with backlit screen | Advanced Honeywell Sola boiler controller with backlit screen |
| Warranty | 15-year limited warranty (5-year basic all components; registered installations extend pressure-vessel coverage through year 15) | 15-year limited warranty (5-year basic all components; registered installations extend pressure-vessel coverage through year 15) |
The EFW-340WBN and EFW-399WBN are built on the same wall platform: 36-5/8 x 25-1/4 x 20 in. cabinet, 250 lb with water, 4 in. vent/air connections with 100 ft maximum runs, 1-1/2 in. male water connections, 3/4 in. male gas, and the shared Honeywell Sola control set with outdoor reset, DHW priority, Modbus RTU and cascade of up to eight boilers.
Both print 95.4% thermal efficiency and both start at the same 39.9 MBH minimum input; the only rating difference is the top of the range — 340 MBH input / 324 MBH heating capacity / 282 MBH net on the 340 against 399 MBH input / 380 MBH heating capacity / 330 MBH net on the 399. The 399 also prints a slightly lower water content (6.4 versus 7.1 gal).
Because the minimum fires match, the two behave the same in mild weather; the 399 only earns its premium when the design-day load or connected volume genuinely needs the extra 56 MBH of heating capacity. Both convert to propane with the documented kits and derate 4% per 1,000 ft above 2,000 ft.
The HTP EFW-340WBN is the 340 MBH class wall-mount model of the current EFW (Elite Firetube Wall Mount) line: 39.9 to 340 MBH input, 324 MBH heating capacity, a 282 MBH net AHRI water rating at 95.4% thermal efficiency, a 4" vent connection and a 250 lb wall package with the Honeywell Sola control.
The HTP EFW-399WBN is the 399 MBH class wall-mount model of the current EFW (Elite Firetube Wall Mount) line: 39.9 to 399 MBH input, 380 MBH heating capacity, a 330 MBH net AHRI water rating at 95.4% thermal efficiency, a 4" vent connection and a 250 lb wall package with the Honeywell Sola control.
Same cabinet, venting, connections, controls and 95.4% printed thermal efficiency — the 399 is the higher-fired version of the same 4 in.-vent platform.
The EFW-399WBN, at 39.9–399 MBH input with 380 MBH heating capacity and a 330 MBH net AHRI water rating.
Yes — both use 4 in. vent/air connections with a 100 ft maximum run per the official page.
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.