Canada-wide gas boiler information · On-site service in Greater Vancouver, BC
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Comparison
Verdict in brief
The FTXL FTX725 is the first FTXL to step its plant: against the FTX600 it fires 103.6 to 725 MBH with 705 MBH gross output, moves water connections to 2-1/2", grows water content to 17.2 gallons and steps the vent to 6", at 97.2% submittal thermal efficiency.
Published manufacturer figures. Input and output are kept separate; blanks mean the manufacturer did not publish that value.
| Specification | Lochinvar FTXL FTX600 | Lochinvar FTXL FTX725 |
|---|---|---|
| Heating input, minimum | 85.7 MBH | 103.6 MBH |
| Heating input, maximum | 600 MBH | 725 MBH |
| Gross output | 585 MBH | 705 MBH |
| Net AHRI water rating | 509 MBH | 613 MBH |
| Efficiency (thermal) | 97.5 % | 97.2 % |
| Water content | 11.9 gal | 17.2 gal |
| Space-heating water connections | 2" | 2-1/2" |
| Gas connection | 1" | 1" |
| Air inlet size | 4" | 4" |
| Vent size | 4" | 6" |
| Shipping weight | 504 lb | 575 lb |
Both are FTXL fire-tube boilers at 7:1 turndown per the submittal, sharing the SMART TOUCH control, stainless steel fire-tube heat exchanger and venting to 100 equivalent feet in PVC, CPVC, polypropylene or AL29-4C stainless steel.
The 725 exists for loads the 600 cannot carry: maximum input rises from 600 to 725 MBH, gross output from 585 to 705 MBH and the AHRI net rating from 509 to 613 MBH, at 97.2% submittal thermal efficiency against 97.5%.
The installation details change at the 725: water connections step from 2" to 2-1/2" and the vent from 4" to 6" (air stays 4"), water content grows from 11.9 to 17.2 gallons and shipping weight from 504 to 575 lb per the submittal — so a retrofit expecting 2" piping stops at the FTX600.
Lochinvar
The FTXL FTX600 reaches 85.7 to 600 MBH input with 585 MBH gross output and a 509 MBH AHRI net rating at 97.5% submittal thermal efficiency, with 7:1 turndown.
Lochinvar
The FTXL FTX725 fires 103.6 to 725 MBH with 705 MBH gross output and a 613 MBH AHRI net rating at 97.2% submittal thermal efficiency, stepping to 2-1/2" water connections and a 6" vent.
No — the I&O ratings table lists 2-1/2" water connections for the 725, with a 6" vent against the 600's 4". Near-boiler piping must be sized for the larger fittings.
The FTXL submittal prints 97.5% thermal efficiency for the FTX600 and 97.2% for the FTX725.
A consultation includes a heat-loss review so the size is right the first time.
On-site service in Greater Vancouver, BC. ROMA lists “Open 7 days” on its site; call to confirm same-day availability.
Sources and verification
Facts checked September 9, 2026. Last updated September 9, 2026. Technical reviewer: not yet assigned.