Canada-wide gas boiler information · On-site service in Greater Vancouver, BC
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Comparison
Verdict in brief
The Lx500 and Lx600 are adjacent steps in the light-commercial Lx class: the Lx600 fires 120 to 600 MBH instead of 100 to 500 MBH and weighs 380 lb against 320 lb. Water connections (2" NPT female) and 4" venting are unchanged; the gas connection steps from 3/4" to 1" NPT male.
Published manufacturer figures. Input and output are kept separate; blanks mean the manufacturer did not publish that value.
| Specification | NTI Trinity Lx500 | NTI Trinity Lx600 |
|---|---|---|
| Input, minimum | 100 MBH | 120 MBH |
| Input, maximum | 500 MBH | 600 MBH |
| Efficiency (AFUE) | 94 % | 94 % |
| Weight | 320 lb | 380 lb |
| Max. equivalent vent length | 100 ft | 100 ft |
| Water connections | 2" NPT female | 2" NPT female |
| Gas connection | 3/4" NPT male | 1" NPT male |
| 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 |
Both models sit in the Lx class that NTI's manual rates by combustion (95%) and thermal (94%) efficiency rather than DOE AFUE, while the product page lists 94% for each. They share 2" NPT female water connections and 4" venting to 100 ft per side.
The Lx600 fires 120 to 600 MBH against the Lx500's 100 to 500 MBH, adding 100 MBH of ceiling and 60 lb of cabinet (380 lb against 320 lb). Its minimum fire rises from 100 to 120 MBH, and its gas connection steps from 3/4" NPT male to 1" NPT male.
Both are heating-only fire-tube boilers for light-commercial plants. The Lx600 is the step when the plant-demand calculation approaches 600 MBH; loads within the 500's range keep the lighter unit with the same water connections and venting.
NTI Boilers
The NTI Trinity Lx500 is the entry of the pure-commercial Lx class: 100 to 500 MBH input at a published 94% AFUE, in a 320 lb floor-standing boiler with 2" water connections and 4" venting to 100 ft.
NTI Boilers
The NTI Trinity Lx600 fires 120 to 600 MBH at a published 94% AFUE, weighing 380 lb with 2" water connections and 4" venting to 100 ft — the largest Lx size that still vents in 4" pipe.
Input rises from 500 to 600 MBH, weight from 320 to 380 lb, and the gas connection from 3/4" to 1" NPT male. Water connections and 4" venting are unchanged.
The product page lists 94% AFUE for both; the I&O manual rates sizes from 500 MBH by combustion (95%) and thermal (94%) efficiency.
120 MBH per the NTI product page, against 100 MBH on the Lx500 — both figures assume a genuine plant load.
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 7, 2026. Last updated September 7, 2026. Technical reviewer: not yet assigned.