I had to replace the control valve on my Bryant 394 HAD last of the standing pilot type Furnas on natural gas and wonder if it is worth doing a manifold pressure test ? The instructions with the White Rodgers replacement valve say it should not be nessary and it does seem to be working ok but I'm thinking maybe the pressure should be checked for best effenciency ?  From what I can find out the pressure should be 3.5 inches WC ?  and I would assume one would plug all but one of the three manifold orfices and take a reading from the one the farthest from the valve being best?

Thanks

Jay