Goodman Furnace: Check gas input by clocking the gas meter
Check gas input by clocking the gas meter on a Goodman furnace: Time one revolution of the meter's smallest dial with the furnace at steady firing, then work out the input in BTU/hr and compare it with the nameplate.
Applies to: Gas furnaces ACVC96/AMVC96/GCVC96/GMVC96
How to fix check gas input by clocking the gas meter: step by step
- Turn off all other gas appliances in the home.
- Run the furnace at 100% firing rate (two-stage or modulating units) and let it reach steady state, about 15 minutes.
- Time one full revolution of the smallest meter dial with a stopwatch. Note the dial size (for example 1 cu ft).
- Find the seconds in the gas rate table for that dial size and read the CFH value.
- Check the CFH with the formula: (3600 x dial size) / seconds = CFH.
- Get the local heating value of the gas from the utility (average is about 1025 BTU per cu ft).
- Calculate input: CFH x BTU content = BTU/hr input.
- If the input is not within 5% of the nameplate rating, adjust the gas valve pressure regulator or resize the orifices.
- Turning the regulator clockwise raises pressure and input. Turning it counterclockwise lowers them.
- Make sure airflow is within limits so the unit does not short cycle, and check temperature rise after any change.
If the unit shows an error code, look it up: Goodman Furnace codes
Source: Goodman GMVC96 service and troubleshooting manual, p. 40-41. 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.