Canada-wide gas boiler information · On-site service in Greater Vancouver, BC
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Comparison
Verdict in brief
The Knight WHB055 and WHB085 are the two smallest wall-hung Knights and are twins below the maximum: both fire near 8.3-8.5 MBH, hold about 2.2-2.3 gallons and are rated 95% AFUE. The 085 adds 30 MBH of heating ceiling (85 versus 55) with 79 MBH of DOE capacity, so a heat-loss calculation decides which the home needs.
Published manufacturer figures. Input and output are kept separate; blanks mean the manufacturer did not publish that value.
| Specification | Lochinvar Knight WHB055 | Lochinvar Knight WHB085 |
|---|---|---|
| Heating input, minimum | 8.3 MBH | 8.5 MBH |
| Heating input, maximum | 55 MBH | 85 MBH |
| DOE heating capacity | 51 MBH | 79 MBH |
| AHRI net water rating | 44 MBH | 69 MBH |
| Efficiency (AFUE) | 95 % | 95 % |
| Water content | 2.3 gal | 2.2 gal |
| Space-heating water connections | 1" | 1" |
| Gas connection | 1/2" | 1/2" |
| Max. equivalent vent/air length, 2" | 80 ft | 50 ft |
| Max. equivalent vent/air length, 3" | 100 ft | 100 ft |
| vent-max-4 | — | — |
| Domestic hot water | Heating-only boiler | Heating-only boiler |
Both models are the same stainless steel fire-tube boiler in the same wall-hung family: 95% AFUE, 1" water connections, a 1/2" gas connection, an ECM boiler pump and the SMART SYSTEM control with text-name faults. The published differences are capacity and the vent table.
Minimum fire barely moves — 8.3 MBH on the 055 versus 8.5 MBH on the 085 — while maximum input jumps from 55 to 85 MBH and DOE heating capacity from 51 to 79 MBH. In mild weather the two behave almost identically; the 085's extra ceiling only matters on design days.
The practical difference is venting: the 055 reaches 80 equivalent feet in 2" pipe and the 085 only 50, though both reach 100 feet in 3". Both are heating-only boilers whose domestic hot water comes from an indirect tank such as Lochinvar's Squire.
Lochinvar
The Knight WHB055 is the entry size of Lochinvar's wall-hung fire-tube Knight: 8.3 to 55 MBH input at 95% AFUE, with 1" water connections and 2" venting to 80 equivalent feet.
Lochinvar
The Knight WHB085 steps the wall-hung Knight to 8.5 to 85 MBH input at 95% AFUE, with 79 MBH DOE capacity and a 2.2-gallon water content in the same 1"-connection cabinet family.
Physically they are siblings in the same wall-hung family with 1" connections; the published difference is that the 085 fires to 85 MBH instead of 55 MBH and its 2" vent allowance shortens from 80 to 50 equivalent feet.
When the heat-loss calculation shows the home can need more than 55 MBH on a design day. Extra ceiling without a matching load only raises the boiler's running time at low fire.
No. Both Knights are heating-only boilers; domestic hot water is stored in an indirect tank such as Lochinvar's Squire and reheated by the boiler.
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 7, 2026. Last updated September 7, 2026. Technical reviewer: not yet assigned.