How to Gas Rate an Appliance?

Gas rate is the measurement of the volume of gas used by an appliance. In order to be correct, learn how to gas rate an appliance. The gas rate value must be within the standard allowed limits of the boiler manufacturers. 

The value of the gas rate indicates whether the appliance is working to its optimal efficiency or not.

Gas rating is a fundamental test to check the efficiency of an appliance. We do it via calculating the amount of gas an appliance burns within a specific time. Typically, the specific time frame of the gas rate test is one hour (3600 seconds).

The gas rate calculation is usually done for a shorter period of time due to practicality. Two ways for Gas Rate Calculation are:

• Imperial
• Metric

In imperial, the gas rate process is to run the appliance for one complete revolution of the test dial (ft³). In metric, the appliance runs under test for 2 minutes, and record the meter reading(m³).

Metric Gas Rate Instructions:

1. Make sure that all the gas burning appliances in the house are off.
2. Turn on the appliance to its maximum setting and let it run for 10 minutes.
3. Record the first meter reading from R1
4. Record the second meter reading from R2 after exactly 2 minutes (120 seconds).
5. Subtract R2-R1 and divide it by 2 to get the gas rating over 1 minute.

Imperial Gas Rate Instructions

1. Make sure that all the gas burning appliances in the house are off.
2. Turn on the boiler to its maximum setting and let it run for 10 minutes.
3. Record the time in seconds it takes for the test dial to complete one revolution (ft³).
4. Calculate the gas rate using the formula:

Gas rate = (3600 x number of ft³ per revolution)/the time taken for the test dial to complete one revolution.

Unit of gas rate for this formula is ft³/hr.

Heat Input

Heat input of an appliance is the amount of energy produced from the quantity of fuel/gas burned. Heat input is calculated with the known volume of gas burned in a boiler in either ft³/hr or m³/hr. There are two ways to calculate heat input:

• kW (for metric)
• btu/hr (for imperial)

For natural gas, the average calorific value (CV) is used:

• m³/hr x 38.76 = MJ/m³

• ft³/hr x 1040 = btu/ft³

In order to convert btu/ft³ to kW, simply divide the value of btu/ft³ by 3412. 

Gas rate an appliance in m³ and convert it to ft³?

The gas rate can be calculated manually or by using a gas rate calculator.

• Turn off the boiler and record the meter reading.
• After recording the meter.
• Start recording the time at the same time as turning on the appliance.
• Record the meter reading after two minutes have elapsed.
• Subtract the reading of the first meter from the reading of the second meter. The remainder will be the volume of gas passed in m³.

Final Words 

Now that you know how to gas rate an appliance, you can now easily gas rate your boiler. Gas rating within the allowed limits ensures that the boiler is working at its highest efficiency. It is essential to ensure that your boiler is working efficiently; otherwise, it can cause a surge in electricity bills.

Get professional Gas Safety Inspections and Plumbing services from GL Plumbing and Gas Engineering Ltd. Contact Us for a professional gas safety inspection.