Average Gas Consumption vs. Gas Utility Requirements

Average Gas Consumption

A common question our customers ask is regarding Utility Requirements so they can correctly size the gas line for the ovens. It’s important to note that those requirements are maximum requirements reflecting when the ovens burners are on full. They do not reflect average consumption. The oven will run at these higher numbers only during heat up. Once the oven reaches temperature the burners are turned down and the average consumption drops substantially. Please consider these examples when calculating daily costs:

Mountain Home ovens
During the first two hours of operation the oven will run at the full rated BTU input noted on the data plate and spec sheets. After the oven reaches operating temperature the radiant burner (RFG) will be throttled back to a holding flame and the gas fired infra-red assist burner (IR) will cycle off. During daily operation the radiant flames will be raised and lowered and the IR will cycle on and off as needed. This usage will average out at roughly 40 percent of the total input rating for the remainder of the day.

Example for a WS-MH-5-RFG-IR on natural gas rated at 188,000 BTU/hr (1.88 therms/hr) running 6 hours per day, with a temperature range of 550F-600F (285C -315C):

188,000 BTU (1.88 therms) per hour for two hours = 376,000 BTU (3.76 therms)
75,200 BTU (.75 therms) per hour for four hours = 300,800 BTU (3.01 therms)

For a total daily use of 677,000 BTU (6.77 therms/day or 1.13 therms/hr)

Bistro Home ovens
During the first two hours of operation the oven will run at the full rated BTU input noted on the data plate. After this heat up period, the oven will be throttled back to a holding flame unless product is being cooked, then turned up averaging 50-60 percent of the total input rating for the remainder of the day.

Example for a Bistro WS-BH-4343-RFG oven on natural gas at a maximum of 80,500 BTU/hr (.8 therms/hr) running six hours per day, with a temperature range of 550F-600F (285C -315C):

80,500 BTU (.8 therms) per hour for two hours = 161,000 BTU (1.61 therms)
40,250 BTU (.4 therms ) per hour for four hours = 161,000 BTU (1.61 therms)

For a daily total of 322,000 BTU (3.22 therms/day or .54 therms/hr)

For comparative purposes:

  • Gas clothes dryer: .3 therms/hr
  • Gas fireplace (35,000 BTU): .35 therms/hr
  • Gas water-heater: .72 therms/day

Formula for calculating total BTUs used by oven:
(BTUs used for Heat-Up) + (BTUs used after heat-up) = total BTUs used

Converting BTUs used to actual gas consumption
Natural gas is typically measured and billed by the therm. A therm contains 100,000 BTUs.

To determine number of therms used:
(Total BTUs used)/100,000 = Total Number of Therms
LP (Liquid Propane) is sold by the gallon. LP contains 91,000 BTUs per gallon.

To determine number of gallons of LP used:
(Total BTUs used)/91,000 = number of gallons of LP used

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