Clocking gas meter

Neild5

How close to name plate rating should clocking the gas meter be? I live in a 20 unit condo building built in 1927 with a single pipe steam system. The boiler has 3 Dundick 500,000 BTU base units tied together. I closed 2 gas valves and clocked the meter for each unit, small meter dial is 5cf , one unit took 48.1 seconds and the center one took 41.7 seconds. I calculated it to 374K and 431K BTU. The third unit is currently down for repairs. First question is my math correct? And if it is correct should they be closer to 500 K each? With one unit down the system has been keeping up with the Chicago winter so as installed it is way over sized with the 3 sections firing. I am trying to build a case for recommending we replace the current contractor with someone who knows and understands steam because the last 2 guys the management company hired are knuckleheads.

BobC

Your math looks good and I agree you seem to have more horsepower than you need. If it's a atmospheric boiler it can be downfired pretty easily, if it's a wet based boiler going more than 10-15% can be a problem. In either case a combustion meter has to be used so you can be sure your getting proper combustion. Are there any combustion printouts on the boilers?

This might help those who want to clock their gas boilers, make sure all other gas appliances are off when doing this.


Correct clocking of a 2PSIG Meter

When ever you have a high pressure meter set, you must compensate for the increased volume of gas at low pressure.  So multiply your calculated consumption by 1.13
So say you take 34 secconds on a 1 cu foot dial:

3600 [secs /hr] X 1 [cu ft dial size] X 1020 [local btu value of gas]
________________________________________________
                               34 [secconds]

=108 000 X 1.13 [2 PSIG conv]= 122 040 BTUs / hr actual consumption rate.

Note due to the limit of how accurate you are eyeballing the time, your calculation will only have accuracy of about +/- 3%