Gas-Meter Clock Target Time
The inverse of meter clocking: the seconds-per-revolution a known test dial SHOULD take if the appliance is firing on rate, so you know the stopwatch reading to expect - sec = 3600 x dial x heating value / target rate. A 100,000 BTU/hr furnace on a 1 cf dial at 1030 BTU/cf should clock 37.1 s (on-rate window 35.3-39.0 s at +/-5%); a faster revolution is overfired, a slower one underfired. Clock with every other gas appliance off. The utility heating value and rating plate govern.
Formula and source
seconds-per-rev = 3600 x dial size x heating value / target rate; on-rate window = sec/1.05 (fast) to sec/0.95 (slow); target cfh = target rate / heating value.
First-principles meter-clocking arithmetic solved for the on-rate time, the inverse of the meter-clock tile (public); the heating value is an editable field.
Audience
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