Canada-wide gas boiler information · On-site service in Greater Vancouver, BC
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Comparison
Verdict in brief
The Lx400 and Lx500 sit on the boundary of NTI's wall-hung-capable and pure-commercial Lx classes: the Lx500 fires 100 to 500 MBH instead of 75 to 399 MBH, moves to 2" water connections and a 3/4" male gas connection, and weighs 320 lb against 225 lb. Both list 94% AFUE on the page.
Published manufacturer figures. Input and output are kept separate; blanks mean the manufacturer did not publish that value.
| Specification | NTI Trinity Lx400 | NTI Trinity Lx500 |
|---|---|---|
| Input, minimum | 75 MBH | 100 MBH |
| Input, maximum | 399 MBH | 500 MBH |
| Efficiency (AFUE) | 94 % | 94 % |
| Weight | 225 lb | 320 lb |
| Max. equivalent vent length | 100 ft | 100 ft |
| Water connections | 1 1/4" NPT female | 2" NPT female |
| Gas connection | 3/4" NPT female | 3/4" 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 |
The Lx400 fires 75 to 399 MBH at 94% AFUE with 1 1/4" NPT female water connections and a 3/4" NPT female gas connection. The Lx500 fires 100 to 500 MBH, also listed at 94% on the page, with 2" NPT female water connections and a 3/4" NPT male gas connection — the first size NTI shows with male gas threading.
Weight jumps from 225 to 320 lb, the minimum fire from 75 to 100 MBH, and the wall-hung kit disappears: the Lx500 is floor-standing only. Both models vent in 4" pipe to 100 ft per side.
On ratings, the Lx500 also crosses the point where NTI's documentation changes treatment: the I&O manual gives DOE AFUE only up to 400 MBH and rates sizes from 500 MBH by combustion (95%) and thermal (94%) efficiency, even though the page prints 94%. For a light-commercial plant whose load approaches 500 MBH, the Lx500 is the entry of that class.
NTI Boilers
The NTI Trinity Lx400 is the last Lx size NTI's page lists for residential-capable use: 75 to 399 MBH input at 94% AFUE in a 225 lb floor-standing boiler (wall-hung kit included) with 4" venting to 100 ft.
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.
No. NTI's wall-hung kit coverage ends with the Lx400; the Lx500 is a floor-standing-only commercial-class boiler at 320 lb.
The page prints 94% AFUE, but the I&O manual gives DOE AFUE only up to 400 MBH and rates sizes from 500 MBH by combustion (95%) and thermal (94%) efficiency.
2" NPT female water connections with a 3/4" NPT male gas connection, and 4" venting to 100 ft per side.
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.