Electrocoolman
19-05-2010, 09:59 AM
Hi Guys, has anyone experience of one of these systems. I'm trying to sort out the 'whole system' , not just the Carrier side.
On the Carrier side, we basically have a load of Slave control units and possibly one (or two) Masters (covers two floors). Each slave controls its own air damper box which is fed from a single common duct which can deliver EITHER warm air OR cool air, but not both at the same time.
As I understand it, the Master polls the slaves to see what their demand is (ie. either Heat or Cool) and this then itself demands (presumably on the majority) either warm air or cool air from the AHU.
The AHU is controlled on the building TREND system, the duct pressure being maintained via a pressure sensor and VSDs controlling the supply and extract fans.
The Trend has x4 temperature set points. x2 Heat and x2 Cool.
What would the typical duct pressure be on such a system?
Does anyone know what signals the Carrier Master outputs? Is it 0 -10v for heating and a separate 0 -10v for cooling ? Are there any other outputs (eg fan speed)?
The other open question is what is the minimum recomended deadband for the room controllers? (ie difference between heating and cooling setpoints).
As this is in a people training enviroment, the small rooms can get 'stuffy' very quickly, so the input of air on a regular basis is relatively important, which if the deadband is too wide, and the damper box remains shut can happen.
Your help and advice would be much appreciated.
As I understand, not many of these systems were installed!
Regards, Adrian.
On the Carrier side, we basically have a load of Slave control units and possibly one (or two) Masters (covers two floors). Each slave controls its own air damper box which is fed from a single common duct which can deliver EITHER warm air OR cool air, but not both at the same time.
As I understand it, the Master polls the slaves to see what their demand is (ie. either Heat or Cool) and this then itself demands (presumably on the majority) either warm air or cool air from the AHU.
The AHU is controlled on the building TREND system, the duct pressure being maintained via a pressure sensor and VSDs controlling the supply and extract fans.
The Trend has x4 temperature set points. x2 Heat and x2 Cool.
What would the typical duct pressure be on such a system?
Does anyone know what signals the Carrier Master outputs? Is it 0 -10v for heating and a separate 0 -10v for cooling ? Are there any other outputs (eg fan speed)?
The other open question is what is the minimum recomended deadband for the room controllers? (ie difference between heating and cooling setpoints).
As this is in a people training enviroment, the small rooms can get 'stuffy' very quickly, so the input of air on a regular basis is relatively important, which if the deadband is too wide, and the damper box remains shut can happen.
Your help and advice would be much appreciated.
As I understand, not many of these systems were installed!
Regards, Adrian.