Have a project with a 12.5ton heat/cool RTU (natural gas 2psig inlet pressure). Unit is running fine, 4900 cfm air delivery. Having an issue with not heating the space fast enough so we verified the unit capacity by clocking the gas meter. We are using/burning 200,000 btuh when the unit is rated at 250,000 btuh (input).
Inlet gas pressure is fine, manifold GP is at 3.5"wc. Called gas company to verify btu content of ft3 gas and that is ok @ 1000. Verified burner orfices and those too are OK.
What next? is possibly the gas meter giving us a false reading? is it somethign with the unit. I am sure we can raise the manifold pressure but that is not according to the manufactures data. Any suggestions. ???