I was able to add a legal third unit 787 sqft.garden apartment within the footprint of the original building. I have an existing 400 meter and a 250 meter supplying gas to the property. The current system would supply enough BTU’s to the property. I have a 1/2 inch high pressure line coming into a two unit building in San Francisco. The original post did not clarify between the rated capacity and the maximum continuous capacity. Let us know what you find and leave a comment below. Time to calculate your total gas demand and then see what size gas meter you have.
#Gas meeter upgrade
After consulting with PG&E, they confirmed that they would upgrade the meter size at no cost to the customer. They can come out and switch your gas meter with a larger size. When gas appliances are starved for gas, they will not function at maximum capacity, and will be prone to soot buildup.īasically, it’s time to call your gas utility provider. Just the act of switching to a modern tankless water heater can increase demand by 160,000 Btu/h or more. For the example building above, the total demand of 200,000 Btu/h is smaller than the meter capacity 250,000 Btu/h and the system should perform as designed.Īdding a new gas appliances or upgrading gas appliances (think a kitchen remodel with a new commercial style range) can upset this balance. As long as the continuous meter capacity is larger than the demand, everything is fine.
Thankfully, this makes them math pretty easy! If you have a meter with a maximum continuous capacity of 250 cf/h, it can provide a maximum of 250,000 Btu/h. The Btu/h per cubic foot of gas can vary, but PG&E uses an average of 1,000 Btu/h for every cf/h of gas. Each appliance will have a date plate with this information, though some can be hard to find. The easiest way to do this is to add up the “British thermal units/hour” (Btu/h) ratings of all the gas appliances. To determine if your gas meter is undersized, you first have to know the total gas demand for your building. Ward recommended adding 15% to the rated capacity as a conservative estimate for the maximum continuous capacity. For example, a meter that is rated for 275 cf/h, can actually provide 385 cf/h of “maximum continuous capacity.” This is based on laboratory testing of each gas meter, and unfortunately there is no standard formula to determine maximum continuous capacity vs. After consulting with Armstead Ward of PG&E’s gas division, it turns out that a meter can provide more gas than its rated capacity. The meter label (see below) will indicate the rated capacity of the meter in cubic feet per hour (cf/h), and out in the field, we typically see meter sizes ranging from 175 cf/h to 275 cf/h. When a gas meter is installed by your gas utility provider (PG&E in our area), they size the meter based upon the total capacity of the gas appliances installed in the building when the meter is installed. If a gas meter is undersized, the attached gas appliances could be starved for gas – especially when the major appliances are running at the same time. While it is commonplace for property inspectors to note the electrical service size and often the size of the main water supply, the size of the gas meter is frequently overlooked.