Lochinvar · Crest (FB / Hellcat FCB)
Lochinvar Crest FBN1251
The Crest FBN1251 fires 62.5 to 1250 MBH with 1203 MBH gross output and a 1043 MBH AHRI net rating at 20:1 turndown, stepping the gas inlet to 1-1/2" and the vent to 8".
Key figures
- Max input
- 1,250 MBH
- Max CSA output
- —
- AFUE
- —
- Min input
- 62.5 MBH
Input is gas energy consumed; output is heat delivered. Never size from input alone.
Lochinvar Crest FBN1251 in practice
The FBN1251 carries the Crest FB line past the million-BTU mark: the I&O ratings table lists 62.5 to 1250 MBH input with 1203 MBH gross output and a 1043 MBH AHRI net water rating, at 20:1 turndown per the manual (matching the 62.5 MBH minimum). Its 87-gallon water content keeps the 3" pipe outlet and inlet of the smaller sizes.
The 1251 is the first Crest size whose vent steps to 8" (air stays 6"), and the gas inlet grows to 1-1/2". Venting is in stainless steel, polypropylene, PVC or CPVC to 100 equivalent feet per the page feature list, and weight with water is 1,975 lb per the ratings table. The family platform — wave fire-tube heat exchanger, SMART TOUCH control with CON·X·US — carries through, with the 10-year heat exchanger warranty printed on the family product page.
Best suited to
- Commercial loads between 1,000 and 1,250 MBH on a design day
- Projects stepping to 1-1/2" gas supply at the boiler
- Systems planned around an 8" vent with 6" air intake
Applicability and support
- Model number
- FBN1251
- 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 | 62.5 MBH | Per the I&O ratings table. |
| Heating input, maximum | 1,250 MBH | Per the I&O ratings table. |
| Output | ||
| Gross output | 1,203 MBH | Per the I&O ratings table. |
| Net AHRI water rating | 1,043 MBH | Per the I&O ratings table. |
| Venting and air | ||
| Air size | 6" | Per the I&O ratings table. |
| Vent size | 8" | Per the I&O ratings table. |
| Venting | Category IV sealed combustion; stainless steel, polypropylene, PVC or CPVC venting | Up to 100 equivalent feet per the Crest product-page feature list. |
| Physical and connections | ||
| Water content | 87 gal | Per the I&O ratings table. |
| Pipe outlet connection | 3" | Per the I&O ratings table. |
| Pipe inlet connection | 3" | Per the I&O ratings table. |
| Gas connection | 1-1/2" | Per the I&O ratings table. |
| Weight with water | 1,975 lb | Per the I&O ratings table. |
Manuals
Alerts documented for this model
- Gas Pressure SW Open
- Low Water Cutoff Open
- Blocked Drain SW Open
- APS Open
- Anti-cycling
- Flame Failure
- Flame Fail Running
- Gas Valve / Relay Failure
- Auto Reset High Limit
- Manual Reset High Limit Open
- Fan Speed Low
- Fan Speed High
- Louver Proving Sw Open
- Flue Temp High
- Delta T High
- Outlet Temp High
- Parameter Programming Complete
- Sensor Open
- Sensor Shorted
- Flue Sensor Open
- Flue Sensor Shorted
- Too Many Resets - Try Later
- Internal Fault
- Flue Temp Shutdown
- Delta T Shutdown
- Outlet Temp Shutdown
- Writing/Programming EEProm Error
- CRC Parameter Error
- Wrong Error Code
- Flame Sense Out of Sequence 1
- Flame Sense Out of Sequence 2
- Flue Damper Switch Open
- IO Expander Out Error
- Failure ADC Controller
- Outlet Sensor Differential
- Flue Sensor Differential
Frequently asked questions
What are the FBN1251's ratings?
62.5 to 1250 MBH of input with 1203 MBH gross output and a 1043 MBH AHRI net water rating per the I&O ratings table, at 20:1 turndown.
What changes at the FBN1251 versus the FBN1001?
Maximum input rises from 999 to 1250 MBH, the gas inlet steps from 1-1/4" to 1-1/2", the vent from 6" to 8", and water content from 77 to 87 gallons; the pipe connections stay 3".
Questions about the Lochinvar Crest FBN1251?
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 Crest FBN1001 vs FBN1251Comparison
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- Lochinvar Crest FBN1001Same series
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- Lochinvar Crest FCB1000Same series
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- Crest (FB / Hellcat FCB) series hub
- Buying guide
Sources and verification
- Lochinvar — Crest Condensing Boiler (FBN1001) model page · accessed September 9, 2026
Facts checked September 9, 2026. Last updated September 9, 2026. Technical reviewer: not yet assigned.