NTI stands for NY Thermal Inc., a boiler maker from Saint John, New Brunswick, founded in 1967. Ariston Group bought the company in 2016, and in November 2025 the business was legally renamed Ariston Canada. The NTI name stays on the boilers. If a search for your boiler leads to an Ariston page, you are in the right place.
The Trinity family is what we find on Ontario basement walls: the early Trinity Ti, the stainless fire-tube Tft, and the Lx and Tx ranges. The Tft is now listed as discontinued, and the TFTN, FTVN and TRX are among the series NTI sells today. Discontinued does not mean unrepairable, but it does mean we confirm that a part exists before we quote it.
Many of these boilers replaced a cast-iron unit in a pre-war brick house in Hamilton or west Toronto and now feed the original radiators. That history matters. Old iron piping sheds sludge into a narrow modern heat exchanger, and a condensing boiler only reaches its rated efficiency when the water returning from the radiators is cool enough for the flue gas to condense.
ZK Mechanical is an independent contractor and services NTI equipment whoever installed it. Gas work on a boiler is done by a TSSA-licensed technician to the CSA B149.1 code, and we leave you the combustion readings in writing.
NTI lines we install and service
The earliest of the wall-hung Trinity condensing boilers and the source of most ignition lockout calls today, simply because of age. Whether one deserves another repair depends on the heat exchanger's condition and on parts supply for that model.
A stainless steel, down-fired fire-tube boiler built in eight sizes from the TFT60 to the TFT399. The fire-tube design tolerates lower flow than older coil-type exchangers, but its condensate still has to drain freely through the trap at the bottom.
Condensing boilers used in larger homes and light commercial buildings. On these we pay particular attention to vent length and the air intake, because a long sidewall run leaves little margin when the intake screen ices over.
A compact wall-hung range that includes combi models heating both the radiators and the domestic hot water. On hard Halton and Hamilton water, the combi's hot-water side scales first, and lukewarm taps are the early sign.
NTI's current wall-hung boilers; the TRX comes as a heating boiler or a combi. If your Trinity is past repair, these are the current equivalents, though we size a replacement from a heat loss calculation and not from the old nameplate.
What goes wrong on NTI equipment
Ignition lockout on an older Trinity Ti
The fan runs, the boiler tries to light, fails and locks out. The igniter wears, the flame rod coats over, and a burner that has not been cleaned in years lights late and rough. The repair is a new igniter and flame rod, a cleaned burner and combustion chamber, new gaskets, and a combustion test afterward. Reset it once; a boiler that locks out again should stay off until it has been opened.
Blocked condensate trap
A condensing boiler makes acidic water all winter, and it leaves through a small condensate trap. When debris from the heat exchanger fills that trap, condensate backs up into the combustion chamber. You hear gurgling, the flame becomes unstable and the boiler locks out, sometimes with water on the floor beneath it. Cleaning the trap is part of every annual service for this reason.
Vent, air intake and fan faults
The control will not open the gas valve until it has proved air is moving. A blocked intake stops it: frost on the sidewall termination, leaves, a wasp nest, snow drifted against the wall. So does a vent pipe that has sagged and filled with water, or a combustion fan that is failing. Clear snow from the terminations yourself; leave the rest to a technician.
Combi runs the radiators but the taps go lukewarm
On a combi model, the domestic hot water is made in a small plate heat exchanger that scales up on hard water. Heating still works, which is how you know the burner is fine. Descaling or replacing the plate exchanger restores it; our combi boiler repair page explains the visit.
NTI warranty: what to know
- Terms are model-specific. For the Trinity Tft, NTI lists a basic 5-year residential warranty on all parts including the pressure vessel, plus extended lifetime residential coverage on the pressure vessel only.
- Do not carry those figures over to a Ti, Lx, Tx or TRX. Each series has its own warranty document, and the one in your installation manual is the one that counts.
- Find out what a claim pays for before you authorize one. A replacement part and the labour to fit it are not the same promise, and the document says which you have.
- Keep your service records. Yearly maintenance invoices with combustion readings, and the original installer's invoice, are the first things a manufacturer asks for when a heat exchanger claim is made.
Parts availability in the GTA
NTI parts move through hydronic heating wholesalers, and the routine service items for a Trinity are straightforward to get: igniters, flame rods, burner and combustion chamber gaskets, condensate traps and pressure sensors. Larger components such as a combustion fan, a gas valve or a control board are ordered against the model and serial number, and on the oldest Trinity Ti boilers we check that the part is still supplied before promising a date. A boiler is the only heat in most of the houses that have one, so if a part is days away we say so and help you plan for temporary heat. The serial plate photo you send us before the visit saves a second trip.
NTI Boiler Error Codes Explained — what each one means and whether it is safe to keep running.
Common questions
Is NTI now Ariston?
The company is. Ariston Group bought NTI in 2016, and the Saint John business was legally renamed Ariston Canada in November 2025. The NTI brand continues on the products, so manuals, part numbers and warranty documents for your boiler are still found under the NTI name. Nothing about the ownership change affects how the boiler is serviced.
Is it safe to reset an NTI boiler that has locked out?
Once, yes. A second lockout is the boiler telling you something is preventing safe combustion, and repeated resets do not fix an igniter, a blocked trap or a starved air intake. Make sure a working carbon monoxide alarm is installed near the sleeping areas, as Ontario law requires in homes with fuel-burning appliances, and call for service.
How often does an NTI condensing boiler need servicing?
Every year, ideally before the heating season. The visit includes opening and cleaning the heat exchanger, inspecting or replacing the igniter and flame rod, flushing the condensate trap, checking the vent and intake, and setting combustion with an analyzer. Our boiler tune-up page lists the full scope.
What does an NTI boiler repair cost?
It depends on the part, how much of the boiler has to come apart to reach it, and whether the system must be drained and refilled. The diagnostic is $90–$150 and is credited to the work. You receive a written price before we start, and our answer on what boiler repair costs explains what drives it.
Should I repair or replace an older Trinity Ti?
Repair it when the fault is an igniter, a flame rod, a fan or a blocked trap and the heat exchanger is sound. Replace it when the heat exchanger is leaking or the part you need is no longer supplied. We inspect the exchanger before recommending either, and our guide on repairing or replacing a boiler walks through the decision.