Canada-wide gas boiler information · On-site service in Greater Vancouver, BC
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Comparison
Verdict in brief
The TFTN600 and TFTN725 are adjacent steps in the floor-mounted TFTN line, and the 725 crosses two installation lines: input rises from 60–600 to 72.5–725 MBH, heating capacity from 585 to 705 MBH and the Net AHRI rating from 509 to 613 MBH, while weight rises from 575 to 685 lb with water, connections step to 2 1/2" water and 1 1/4" gas, and venting moves from 4" to 6" pipe.
Published manufacturer figures. Input and output are kept separate; blanks mean the manufacturer did not publish that value.
| Specification | NTI Trinity TFTN600 | NTI Trinity TFTN725 |
|---|---|---|
| Input, minimum | 60 MBH | 72.5 MBH |
| Input, maximum | 600 MBH | 725 MBH |
| Thermal efficiency | 97.8 % | 97.7 % |
| Heating capacity | 585 MBH | 705 MBH |
| Net AHRI rating | 509 MBH | 613 MBH |
| Weight | 575 lb | 685 lb |
| Water content | 12.5 gal | 17.5 gal |
| CH water connections | 2" NPT | 2 1/2" NPT |
| Gas connection | 1" NPT | 1 1/4" NPT |
| Domestic hot water | Heating-only; pair with an indirect tank or separate water heater | Heating-only; pair with an indirect tank or separate water heater |
The TFTN600 fires 60 to 600 MBH at 97.8% thermal efficiency with a 585 MBH heating capacity and a 509 MBH Net AHRI rating, in a 575 lb with-water chassis with 2" water connections, a 1" gas connection and 4" venting. The TFTN725 fires 72.5 to 725 MBH at 97.7% thermal efficiency with a 705 MBH heating capacity and a 613 MBH Net AHRI rating.
The 725 moves to the larger floor class: 685 lb with water, 17.5 gallons of water content, 2 1/2" male NPT water connections, a 1 1/4" male NPT gas connection and 6" venting to 150 ft per side. The efficiency difference is negligible — 97.7% against 97.8% — so the real costs of stepping up are the minimum fire (72.5 MBH against 60 MBH) and the mechanical-room changes in piping and vent size.
Both sizes run on natural gas or propane per NTI's TFTN500–850 conversion instructions. The 725 is justified when the plant-demand calculation exceeds the 600's ceiling and the boiler room can take 2 1/2" piping with 6" venting; loads inside the 600's range keep the lighter 575 lb unit on the simpler 2" and 4" plan.
NTI Boilers
The NTI Trinity TFTN600 lifts the floor-mounted TFTN to a 600 MBH ceiling: 60 to 600 MBH input at 97.8% thermal efficiency, a 585 MBH heating capacity and a 509 MBH Net AHRI rating, sharing the 575 lb with-water weight and 2" water connections of the TFTN500.
NTI Boilers
The NTI Trinity TFTN725 is the second-largest floor-mounted TFTN: 72.5 to 725 MBH input at 97.7% thermal efficiency, a 705 MBH heating capacity and a 613 MBH Net AHRI rating, stepping to 685 lb with water, 2 1/2" NPT water connections and 6" venting.
Input rises from 60–600 to 72.5–725 MBH, heating capacity from 585 to 705 MBH, the Net AHRI rating from 509 to 613 MBH and weight from 575 to 685 lb with water; connections step to 2 1/2" water and 1 1/4" gas, and venting from 4" to 6" pipe.
No — NTI lists 97.7% thermal efficiency for the 725 against 97.8% for the 600, so the step is about capacity rather than efficiency.
Yes. The 725 vents in 6" pipe to 150 ft per side, against 4" pipe on the 500 and 600, so the boiler-room vent route is part of the model decision.
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 8, 2026. Last updated September 8, 2026. Technical reviewer: not yet assigned.