Lochinvar · Knight Floor Mount (KHB)
Lochinvar Knight KHB155
The Knight KHB155 is the 155 MBH floor-standing Knight: 15.5 to 155 MBH input at 95% AFUE with 144 MBH DOE capacity, vented in 3" pipe to 100 equivalent feet.
Key figures
- Max input
- 155 MBH
- Max CSA output
- —
- AFUE
- 95 %
- Min input
- 15.5 MBH
Input is gas energy consumed; output is heat delivered. Never size from input alone.
Lochinvar Knight KHB155 in practice
The KHB155 is the floor answer to the WHB155: 15.5 to 155 MBH of input, 144 MBH of DOE heating capacity and a 125 MBH AHRI net rating at 95% AFUE. Larger homes with radiators or several zones whose calculated load reaches 150 MBH are where this size earns its place on a basement floor.
Water content rises to 3.2 gallons on 1" heating connections with a 1/2" gas connection. From the 155 size upward the ratings table lists 3" venting only, to 100 equivalent feet, so an existing 2" run cannot serve a KHB155. Domestic hot water is handled by an indirect tank driven by the SMART SYSTEM.
Best suited to
- Homes with loads from 110 to 155 MBH preferring a floor-standing boiler
- Radiator or multi-zone systems with a heavy design-day load
- Basement plants already committed to 3" venting
Applicability and support
- Model number
- KHB155L
- 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 | 15.5 MBH | Per the I&O ratings table. |
| Heating input, maximum | 155 MBH | Per the I&O ratings table. |
| Output | ||
| DOE heating capacity | 144 MBH | DOE heating capacity per the I&O ratings table. |
| AHRI net water rating | 125 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, 3" | 100 ft | Table 3D (air intake/vent piping sizes), I&O manual. |
| Physical and connections | ||
| Water content | 3.2 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. |
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
Why does the KHB155 require 3" venting?
From the 155 size up, the I&O ratings and Table 3D list 3" vent/air piping only, to 100 equivalent feet. The 2" option ends at the 110 size.
What are the KHB155's ratings?
15.5 to 155 MBH input, 144 MBH DOE heating capacity and a 125 MBH AHRI net water rating at 95% AFUE per the KHB I&O ratings table.
Questions about the Lochinvar Knight KHB155?
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
- Lochinvar Knight KHB110 vs KHB155Comparison
- Lochinvar Knight KHB155 vs KHB199Comparison
- Lochinvar Knight KHB055Same series
- Lochinvar Knight KHB085Same series
- Lochinvar Knight KHB110Same series
- Lochinvar Knight KHB199Same series
- Lochinvar Knight KHB285Same series
- Knight Floor Mount (KHB) series hub
- Buying guide
Sources and verification
- Lochinvar — Knight Fire Tube Floor Mount (KHB055L) model page · accessed September 7, 2026
- Knight Fire Tube Boiler (KHB055-285) I&O Manual, Rev M · Rev M · accessed September 7, 2026
Facts checked September 7, 2026. Last updated September 7, 2026. Technical reviewer: not yet assigned.