Lochinvar · Knight Wall Mount (WHB)
Lochinvar Knight WHB055
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.
Key figures
- Max input
- 55 MBH
- Max CSA output
- —
- AFUE
- 95 %
- Min input
- 8.3 MBH
Input is gas energy consumed; output is heat delivered. Never size from input alone.
Lochinvar Knight WHB055 in practice
The WHB055 opens the Knight wall-hung line at 55 MBH of maximum input while firing down to 8.3 MBH, which lets a small home's boiler track mild shoulder-season loads instead of cycling. It is rated 95% AFUE and delivers 51 MBH of DOE heating capacity and a 44 MBH AHRI net water rating, per the I&O ratings table.
The unit is heating-only, so domestic hot water comes from an indirect tank such as Lochinvar's Squire, which the SMART SYSTEM control can drive through its tank-sensor input. It holds 2.3 gallons of water, connects on 1" heating fittings with a 1/2" gas connection, and vents in 2" pipe to 80 equivalent feet or 3" to 100. The product page lists a 15-year heat exchanger and 5-year parts warranty, and in Canada plastic venting must be ULC S636 certified.
Best suited to
- Smaller homes whose heat-loss calculation fits comfortably below 55 MBH
- Systems pairing a compact wall-hung boiler with an indirect tank
- Installations where the 8.3 MBH minimum fire matters in mild weather
Applicability and support
- Model number
- WHB055L
- Canadian availability
- available
- Production status
- current
- ROMA supplies
- Confirmed at consultation
- ROMA services
- Confirmed at consultation
- Warranty
- Series terms
Where ROMA provides on-site service
On-site service is currently offered in Greater Vancouver, BC, including Vancouver, Burnaby, Richmond, Surrey, Coquitlam, North Vancouver, West Vancouver, New Westminster, Port Coquitlam, Port Moody, Delta, Langley, Maple Ridge, Abbotsford, Chilliwack, White Rock, Pitt Meadows, Tsawwassen, Anmore, Lions Bay, Belcarra, Bowen Island, Mission. Everything else on this site is reference information you can use anywhere in Canada.
Specifications
Published specifications
Values as published by Lochinvar. Units are shown with every value; notes flag conflicting sources or missing figures.
| Specification | Value | Note |
|---|---|---|
| Input | ||
| Heating input, minimum | 8.3 MBH | Per the I&O ratings table. |
| Heating input, maximum | 55 MBH | Per the I&O ratings table. |
| Output | ||
| DOE heating capacity | 51 MBH | DOE heating capacity per the I&O ratings table. |
| AHRI net water rating | 44 MBH | Net AHRI rating based on a piping and pickup allowance of 1.15. |
| Efficiency | ||
| Efficiency (AFUE) | 95 % | 95% AFUE per the I&O ratings table. |
| Domestic hot water | ||
| Domestic hot water | Heating-only boiler | Pairs with the Squire indirect water heater or another indirect tank; the Knight is heating-only. |
| Venting and air | ||
| Venting | Category IV sealed combustion; PVC, CPVC, polypropylene or stainless steel | In Canada, plastic venting must be a ULC S636-certified system. |
| Max. equivalent vent/air length, 2" | 80 ft | Table 3D (air intake/vent piping sizes), I&O manual. |
| Max. equivalent vent/air length, 3" | 100 ft | Table 3D (air intake/vent piping sizes), I&O manual. |
| Physical and connections | ||
| Water content | 2.3 gal | Per the I&O ratings table. |
| Space-heating water connections | 1" | Per the I&O ratings table. |
| Gas connection | 1/2" | Per the I&O ratings table. |
| Shipping weight | 169 lb | Shipping weight per the Lochinvar product page. |
| Height | 39.063 in | Wall-mounted cabinet, per the Lochinvar product page. |
| Width | 18.75 in | Wall-mounted cabinet, per the Lochinvar product page. |
Manuals
Alerts documented for this model
- Gas Pressure SW
- Flow Switch/LWCO
- Air Pressure SW
- Too Many Recyclings
- Anti-cycling
- Flame Fail Ign
- Flame Sequence
- Outlet ARHL
- Outlet MRHL
- Fan Speed
- Inlet, Outlet, or Flue Sensor Fault
- AUX Contact Sw
- Outlet Temp Diff
- Fatal Error
- Memory Error
- Flue Temp High / Flue Temp Limit
- Delta T High / Delta T Limit
- Outlet Temp High / Outlet Temp Limit
- Low 24 vac
- Watch Dog Error
- Write EEProm
- CRC Parameters
- No Error Stored
Frequently asked questions
What is the input range of the WHB055?
The I&O ratings table lists 8.3 to 55 MBH of input, with 51 MBH DOE heating capacity and 44 MBH AHRI net water at 95% AFUE.
Can the WHB055 be vented in 2" pipe?
Yes, to a maximum of 80 equivalent feet in 2". The I&O manual also allows 3" venting to 100 equivalent feet for the 055 size.
Questions about the Lochinvar Knight WHB055?
Describe what the boiler is doing and get a straight answer about the next step.
On-site service in Greater Vancouver, BC. ROMA lists “Open 7 days” on its site; call to confirm same-day availability.
Compare and explore
Sources and verification
- Lochinvar — Knight Fire Tube Wall Mount (WHB055L) model page · accessed September 7, 2026
- Knight Wall Hung Fire Tube (WHB055-399) I&O Manual, Rev T · Rev T · accessed September 7, 2026
Facts checked September 7, 2026. Last updated September 7, 2026. Technical reviewer: not yet assigned.