Techniques determine if a gas service (e.g., piping and/or meter) is undersized for the customer's needs. In one example, flowrate information corresponding to gas usage at a service site over a first period of time is obtained. The flowrate information is disaggregated to determine an expected flowrate associated with each of two or more appliances having generally fixed-rates of gas consumption. Flowrate information is again obtained, corresponding to a second period of time. The second flowrate information is compared to one or more combinations (i.e., summations) of the expected flowrates associated with each of the two or more appliances. Based on the comparison, it may be determined that the service site is not appropriately sized. In an example, failure to detect two fixed-rate of gas-consumption appliances operating at their respective fixed-rates at the same time may indicate that the service cannot provide gas at a sufficient flowrate.