Plan gas capacity for every connected appliance. Account for diversity, fuel heating value, and reserve. Choose the next larger meter size with confidence always.
| Appliance | Rated input | Qty | Usage factor | Connected BTU/hr | Diversified BTU/hr |
|---|---|---|---|---|---|
| Furnace | 80,000 BTU/hr | 1 | 1.00 | 80,000 | 80,000 |
| Water heater | 40,000 BTU/hr | 1 | 1.00 | 40,000 | 40,000 |
| Range | 65,000 BTU/hr | 1 | 0.60 | 65,000 | 39,000 |
| Dryer | 22,000 BTU/hr | 1 | 0.50 | 22,000 | 11,000 |
With heating value 1000 BTU/ft³, demand factor 100%, and 10% margin, design load = 170,500 BTU/hr and required flow ≈ 171 CFH.
Correct meter capacity prevents low pressure, nuisance shutdowns, and incomplete combustion. Undersized meters can cause unstable flames and reduce equipment life. Oversizing may increase utility charges and complicate regulator selection. A sizing worksheet supports coordination with the gas supplier, mechanical designer, and commissioning team.
List every gas appliance, its rated input, and quantity. Use manufacturer nameplate ratings for burners, boilers, furnaces, water heaters, generators, and make‑up air units. Convert mixed units to BTU per hour so all items share one basis. Multiply each rating by quantity to obtain connected load, then review for future allowances. Include outdoor heaters, pool equipment, and standby appliances often missed during early design.
Not all appliances run at full input at the same time. Usage factors represent coincidence, cycling behavior, and operational schedules. Residential cooking equipment may have lower coincidence than space heating, while commercial kitchens may be closer to continuous. A demand factor can scale diversified load to reflect peak design intent, tenant flexibility, or utility guidance. When uncertain, document assumptions and add a conservative margin.
Design load equals diversified load multiplied by demand factor and safety margin. Required flow in cubic feet per hour equals design BTU per hour divided by heating value in BTU per cubic foot. For metric reporting, convert using 1 m³/h = 35.3147 CFH. Select the next larger meter capacity that meets or exceeds required flow, then confirm pressure class and regulator limits. If flow is near the rating, consider a higher class meter or split services.
Verify service line length, pipe sizing, and regulator setpoints because friction losses reduce delivered capacity. Confirm local meter offerings, permitted locations, and inspection requirements and approvals. Exportable results support permit submittals, scope reviews, and turnover documentation for facility operations. Keep the appliance schedule updated through procurement so equipment substitutions do not invalidate the final meter request.
Use the value provided by your local supplier when available. If not, start with typical published values, then verify during utility coordination to avoid flow errors.
Usage factor applies per appliance to reflect coincidence. Demand factor scales the diversified total for peak planning, policy requirements, or tenant growth.
Margins cover uncertainty, future appliances, and operational variability. They reduce the risk of low pressure at peak conditions without drastically oversizing the service.
No. Pressure depends on service piping, regulators, and losses. Confirm pipe sizing and regulator capacity to ensure pressure at the most remote appliance.
Rotary meters are commonly used for higher flows, tighter accuracy needs, or certain commercial applications. Confirm availability and requirements with the utility.
Use it as a documented estimate with assumptions. Many authorities and utilities require stamped designs or specific meter standards, so attach schedules and confirm criteria.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.