HVAC Static Pressure Issue
HVAC Static Pressure Issue
(OP)
Hello there,
Let me give a brief history of the issue:
Our HVAC runs at 900 pascals supply static pressure set-point and our supply fan maintains this just fine. At irregular intervals however we have a sudden dip in pressure of roughly 50 pa and the fan will ramp up to counteract and it will take a few oscilations (four minutes) to steady out again. This all sounds ok but the more this happens the more the pulley belts are loaded and damaged (due to the ramping up and down) until a point where the fan throws the belts and we have a failure.
We have changed the static pressure transmitter, changed the motor, alligned the pulleys and went through many many belts.
Has anybody dealt with or witnessed a similar problem with HVAC systems. We are running out of ideas!!
Kind and warm regards,
Thomas
Let me give a brief history of the issue:
Our HVAC runs at 900 pascals supply static pressure set-point and our supply fan maintains this just fine. At irregular intervals however we have a sudden dip in pressure of roughly 50 pa and the fan will ramp up to counteract and it will take a few oscilations (four minutes) to steady out again. This all sounds ok but the more this happens the more the pulley belts are loaded and damaged (due to the ramping up and down) until a point where the fan throws the belts and we have a failure.
We have changed the static pressure transmitter, changed the motor, alligned the pulleys and went through many many belts.
Has anybody dealt with or witnessed a similar problem with HVAC systems. We are running out of ideas!!
Kind and warm regards,
Thomas





RE: HVAC Static Pressure Issue
RE: HVAC Static Pressure Issue
RE: HVAC Static Pressure Issue
A 50 pa deviation from setpoint is probably not significant to the operation of this system anyway. I would start by slowing down the control response.
---KenRad
RE: HVAC Static Pressure Issue
I agree with the previous responses but I think that you should also check you decel rate parameter in your VFD. Your fan could have a high inertial load and be slowing down at a slower rate than the motor. This would cause the belt tension to be reversed and possible cause the belts to come off.
RE: HVAC Static Pressure Issue
Thanks for the many replies so far.
Thomas
RE: HVAC Static Pressure Issue