Lochinvar · Noble Fire Tube (NKB/NKC/NCF)
Lochinvar Noble NKB150
The Noble NKB150 is the 150 MBH Noble heating boiler: 15 to 150 MBH input at 95.0% AFUE with 139 MBH DOE capacity, 1" sweat connections and 2" venting to 60 equivalent feet.
Key figures
- Max input
- 150 MBH
- Max CSA output
- —
- AFUE
- 95 %
- Min input
- 15 MBH
Input is gas energy consumed; output is heat delivered. Never size from input alone.
Lochinvar Noble NKB150 in practice
The NKB150 lifts the Noble boiler to 15 to 150 MBH of input with 139 MBH of DOE heating capacity and a 121 MBH AHRI net rating at 95.0% AFUE, and its 2-gallon water content is the largest of the NKB line. It is the heating-only Noble for detached homes with radiators or in-floor loops whose calculated load reaches 150 MBH.
As with every NKB, water connections are 1" sweat fittings (combi models use NPT) with a 1/2" gas connection. Venting stays flexible but the 2" allowance drops to 60 equivalent feet at the 150 size while 3" reaches 100, so long runs use 3" pipe. Domestic hot water comes from an indirect tank such as the Squire.
Best suited to
- Larger homes whose heat-loss calculation approaches 150 MBH
- Heating-only designs that pair the boiler with an indirect tank
- Projects wanting the Noble's compact fire-tube cabinet at 150 MBH
Applicability and support
- Model number
- NKB150L
- 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 MBH | Per the I&O ratings table. |
| Heating input, maximum | 150 MBH | Per the I&O ratings table. |
| Output | ||
| DOE heating capacity | 139 MBH | DOE heating capacity per the I&O ratings table. |
| AHRI net water rating | 121 MBH | Net AHRI rating based on a piping and pickup allowance of 1.15. |
| Efficiency | ||
| Efficiency (AFUE) | 95 % | 95.0% AFUE per the I&O ratings table. |
| Domestic hot water | ||
| Domestic hot water | Heating-only boiler | The NKB is heating-only; Lochinvar's residential page pairs the Noble wall-mount boiler with the Squire indirect water heater. |
| 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" | 60 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 gal | Per the I&O ratings table. |
| Space-heating water connections | 1" (sweat) | Noble ratings: NPT connections are used on combi units, sweat connections on the boiler. |
| Gas connection | 1/2" | Per the I&O ratings table. |
Manuals
Alerts documented for this model
- Memory Error
- Fan Speed
- LWCO
- Flame Sequence
- Outlet ARHL
- Air Pressure Switch
- AUX Limit Fault
- Flame Fail: Running
- Flame Fail: Ignition
- Flue Temp Limit
- Flue Temp High
- Outlet MRHL
- Outlet Temp High
- Outlet Temp DIFF
- Flue Sensor Fault
- Outlet Sensor Fault
- Inlet Sensor Fault
- Set Point Met
- Anti-Cycling
- Delta T High
- Low Voltage
- No Flue Temp Change
- Combi Sensor Fault (Combi Only)
- Lockout Inlet Sensor Fault
- Outdoor Sensor Missing
- No Hot Water at Faucets (Combi Only)
- DHW Water is not Hot Enough (Combi Only)
- Combi Boiler is Running but Does Not Supply Heated Water to Space Heating System (Combi Only)
- Space Heating System Heat Emitters Get Hot During a DHW Draw and the Combi Boiler does not Provide Hot Enough Domestic Hot Water (Combi Only)
- Lockout! Water Press Switch
Frequently asked questions
What is the NKB150's firing range?
15 to 150 MBH of input per the Noble I&O ratings table, with 139 MBH DOE heating capacity and a 121 MBH AHRI net water rating at 95.0% AFUE.
How does venting change at the 150 size?
The 2" vent allowance drops from 100 to 60 equivalent feet at the 150 size, while 3" venting stays at 100 equivalent feet, per Table 3A.
Questions about the Lochinvar Noble NKB150?
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 Noble NKB110 vs NKB150Comparison
- Lochinvar Noble NKB150 vs NKB199Comparison
- Lochinvar Noble NKB080Same series
- Lochinvar Noble NKB110Same series
- Lochinvar Noble NKB199Same series
- Lochinvar Noble NKC110Same series
- Lochinvar Noble NKC150Same series
- Lochinvar Noble NKC199Same series
- Lochinvar Noble NCF110Same series
- Lochinvar Noble NCF150Same series
- Lochinvar Noble NCF199Same series
- Noble Fire Tube (NKB/NKC/NCF) series hub
- Buying guide
Sources and verification
- Lochinvar — Noble Fire Tube Boiler (NKB080L) model page · accessed September 7, 2026
- Noble Fire Tube Boiler and Combi I&O/Service Manual, Rev AN · Rev AN · accessed September 7, 2026
Facts checked September 7, 2026. Last updated September 7, 2026. Technical reviewer: not yet assigned.