NTI Boiler: Primary/secondary piping for TRX150 / TRX199 with separate central heating circulator

Primary/secondary piping for TRX150 / TRX199 with separate central heating circulator on a NTI boiler: Use when the boiler's internal circulator cannot give enough flow to the secondary circuits.

Homeowner with a boiler problem? Call (647) 657-2977 or book a service call — licensed technicians across Vaughan and the GTA.

Applies to: TRX150 / TRX199 with multiple or single central heating circulators

How to fix primary/secondary piping for trx150 / trx199 with separate central heating circulator: step by step

1. Pipe the heating loop as primary/secondary, with closely spaced tees within 4 pipe diameters centre to centre.
2. Keep at least 6 pipe diameters of straight pipe upstream and downstream of closely spaced tees.
3. Keep at least 12 pipe diameters of straight pipe upstream of every circulator.
4. Use flow/check valves with weighted seats at or near the boiler where there is a single zone, to stop gravity circulation.
5. Support the circulators separately; the piping does not carry their weight.
6. Maintain at least 2 gpm through the heat exchanger to limit short cycling.
7. Use a mixing valve on indirect water heater (IWH) applications if DHW is set above 119°F.

If the unit shows an error code, look it up: NTI Boiler codes

Models

TRX085TRX110CTRX150TRX199TRX199C