Lochinvar · Knight XL Commercial (KBX)
Lochinvar Knight XL KBX1000
The Knight XL KBX1000 tops the commercial Knight XL line at 99.9 to 999 MBH input with 969 MBH gross output and an 843 MBH AHRI net rating at 97% thermal efficiency, stepping to 2-1/2" water and 6" air connections.
Key figures
- Max input
- 999 MBH
- Max CSA output
- —
- AFUE
- —
- Min input
- 99.9 MBH
Input is gas energy consumed; output is heat delivered. Never size from input alone.
Lochinvar Knight XL KBX1000 in practice
The KBX1000 is the largest Knight XL Commercial: the I&O ratings table lists 99.9 to 999 MBH input with 969 MBH gross output and an 843 MBH AHRI net water rating at 97% thermal efficiency, and the product page's model selector tops out at 999,000 BTU/hr on this size. Water content reaches 8.8 gallons, the water connection steps to 2-1/2", the gas connection stays 1-1/4", and both air intake and vent are 6".
It shares the family's floor-mounted stainless steel water-tube condensing design with the SMART TOUCH control, CON·X·US, ENERGY STAR certification and ASME H stamp, and vents in PVC, CPVC, polypropylene, ABS or stainless steel to 150 equivalent feet per the submittal. The submittal prints a 567 lb shipping weight — the heaviest in the line — and the common vent kit (KBX0500-KBX1000) covers this size.
Best suited to
- Large commercial and institutional heating loads approaching 1,000 MBH
- Plants sized for 2-1/2" water connections at the boiler
- Systems where the 99.9 MBH minimum fire still fits the building's part-load profile
Applicability and support
- Model number
- KBX1000
- 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 | 99.9 MBH | Per the I&O ratings table. |
| Heating input, maximum | 999 MBH | Per the I&O ratings table. |
| Output | ||
| Gross output | 969 MBH | Per the I&O ratings table. |
| Net AHRI water rating | 843 MBH | Net AHRI rating based on a piping and pickup allowance of 1.15, per the I&O rating notes. |
| Efficiency | ||
| Efficiency (thermal) | 97 % | 97% thermal efficiency per the product-page spec block; the KBX submittal prints 97.0%. |
| Venting and air | ||
| Air inlet size | 6" | Per the I&O ratings table. |
| Vent size | 6" | Per the I&O ratings table. |
| Venting | Category IV sealed combustion; room air/direct vent in PVC, CPVC, polypropylene, ABS or stainless steel | Direct-vent vertical or horizontal up to 150 equivalent feet per the KBX submittal; concentric vent kit KBX0400-KBX650 and common vent kit KBX0500-KBX1000 listed among the submittal venting options. |
| Physical and connections | ||
| Water content | 8.8 gal | Per the I&O ratings table. |
| Space-heating water connections | 2-1/2" | Per the I&O ratings table. |
| Gas connection | 1-1/4" | Per the I&O ratings table. |
| Shipping weight | 567 lb | Shipping weight per the KBX submittal. |
Manuals
Alerts documented for this model
- Gas Pressure SW
- Flow Switch/LWCO
- Blocked Drain SW/HEX O-Temp SW
- APS Open
- Anti-cycling
- Flame Fail Ign
- Flame Sequence
- Outlet ARHL
- Outlet MRHL
- Fan Low/High OR Fan Speed Low/High
- Sensor Open
- Sensor Shorted
- Louver Proving Sw
- Inlet Sensor Fault
- Outlet Sensor Fault
- Outlet Temp Diff
- Flue Sensor Fault
- Flue Temp Diff
- Flue Temp Limit
- Fatal Error
- Memory Error
- Flue Temp High
- Delta T High
- Outlet Temp High
- Rem Ctrl Flt
- Parameters Progr
- Service Blk
- Low 24 vac
- Watch Dog Error
- Write EEProm
- CRC Parameters
- No Error Stored
Frequently asked questions
What are the KBX1000's ratings?
99.9 to 999 MBH of input with 969 MBH gross output and an 843 MBH AHRI net water rating at 97% thermal efficiency, per the I&O ratings table.
How does the KBX1000 connect?
The ratings table lists 2-1/2" water connections, a 1-1/4" gas connection, a 6" air intake and a 6" vent, with an 8.8-gallon water content.
Questions about the Lochinvar Knight XL KBX1000?
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.
Sources and verification
- Lochinvar — Knight XL Commercial Boiler (KBX0400N) model page · accessed September 9, 2026
Facts checked September 9, 2026. Last updated September 9, 2026. Technical reviewer: not yet assigned.