NTI Boiler: Excess flow valve (EFV) in the gas line
Excess flow valve (EFV) in the gas line on a NTI boiler: Undersized EFV starves the boiler. Check its flow rating against the TRX150 input.
Applies to: TRX150 gas line
Common causes of excess flow valve (efv) in the gas line
- EFV rated below the boiler gas demand, so it trips or chokes flow at high fire
- EFV rated above the boiler range, so it may not protect the line as intended
- Boiler runs rough or locks out only at high input, a typical sign of a restricted gas line
How to fix excess flow valve (efv) in the gas line: step by step
- Find the EFV rating on its label or the maker's sheet, because it is rated in flow, not in pipe size.
- Compare the min and max flow rating to the boiler input.
- If the rating is outside the range, replace the EFV. Gas work, so use a licensed gas fitter.
- After any gas work, leak check every joint you disturbed.
- Watch a full call for heat to confirm the boiler holds high fire.
Safety: Gas, electrical and refrigerant work must be done by a licensed technician. Turn off power and gas before servicing, never bypass a safety control, and always follow the manufacturer's manual for your exact model.
If the unit shows an error code, look it up: NTI Boiler codes
Models
TRX085TRX110CTRX150TRX199TRX199C
Source: NTI TRX150 manual, p. 55. Written in our own words as a summary; always check the original manual.
General guidance for qualified technicians. The manufacturer's installation and service manual and local codes always take priority. Aurora Star Tech is not affiliated with, endorsed by or sponsored by any equipment manufacturer; brand and model names are used only to identify equipment and belong to their owners.