HVACopediaTrane · Furnace troubleshooting
Gas supply pressure testing
What is going on
Gas line pressure testing and the furnace valve: protect the valve from test pressure above 1/2 psig. Higher than that damages the gas valve.
Likely causes
- Furnace left connected during a test above 1/2 psig
- Individual manual shut-off valve left open on a low pressure test
- Test pressure not matched to isolation method
Check in this order
- For tests above 1/2 psig (3.5 kPa), disconnect the furnace and its shut-off valve from the gas supply.
- For tests at or below 1/2 psig (3.5 kPa), close the furnace's individual manual shut-off valve to isolate it.
- Cap the open line before pressurizing.
- After the test, reconnect and leak check all joints before opening the valve.
Applies to: Gas line pressure tests
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Source: Trane 18-CD29D1-11 installer's guide, p. 35. Written in our own words; check the manual for your exact model.
For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.