It is a 7ton split system constant volume air handler supplying to 8 VAV's. They have a VFD to control fan speed by static pressure. Obviously when VAV's are closed, and outside air is closed VFD ramps down to below 30hz. (50%). They are using a discharge bypass valve to control suction pressure due to this loss of airflow. When the hot gas bypass opens it does not regulate, but just rushes hot gas in at a noisy rate. almost like air brakes coming on in a tractor trailer. Then it hunts and keeps doing it over and over again.
The system is equipped with the HGBE-8 pilot operated valve. I contacted sporlan, and they say the valve is too big. They say the HGBE 5 is what i need for a 7 ton application. I ordered it and will see if that works. I was just wondering if anyone has experienced this, and if someone could help me with sizing a HGBP valve that would be great! They are sized in capacity released and not tonnage of unit.