Mind you I do not work on aaons equipment and my knowledge of them is because I work for a smaller competitor of them. Aaon should have programming to prevent this as it sounds like you are just sending a setpoint to aaons control board instead of having direct control of the valves. IT sounds like you are getting high pressure trips because the equipment is closing the valve feeding the condensing coil to much. I believe Aaons hot gas returns before the metering device and as such is not likely capable of completely closing the discharge valve completely. Depending on the design of the equipment you may, or may not be able to close the condensing coil valve completely when the modulating reheat valve is open 100%. One that opens to send hot gas to the reheat coil and one that restricts the flow to the condensing coil forcing more gas into the reheat. The modulating hot gas reheat system uses two valves. The modulating hot gas reheat valve has to increase the flow to compensate to maintain 70☏. When you decrease the airflow across the Dx coil the leaving air temperature decreases as well. The AAON rep can't get them to tell us what they are doing. Seems like they know how to make this work and they keep it close to the chest. Is it more likely that something else is causing the problems? This unit was stripped of the wattstopper controls. It can change by +/- 10 psi in a matter of seconds. Let me ask this, will low airflow cause the high head pressure trips? What feedback should tell me not to turn those later stages on? The suction pressure sensor is all over the place and really hard to control. I will find the high head pressure switches tripped on stage 3 & 4. If I calculate my CFM per ton below 115 CFM per ton. Sometimes the suction pressure will not go below 135 psi until I have all 4 stages on. I enable the reheat and give it a 70 deg f set point. The start up guy told me when I'm in dehum to modulate the stages to maintain 135 psi suction pressure on stage 1. My issue (I think) is when the boxes are at minimum and the unit goes into dehumidification. Units have minimum outside air and are providing air to cooling only vav boxes. Units are 4 stages of DX: 2 variable scroll and 2 are regular. If you have any problems with the registration process or your account login, please contact support. We suggest not registering using an AT&T, BellSouth, AOL or Yahoo email address. Gain access to our free AOP (Ask a Professional) Section to get real answers for your questions.Īll this and much more is available to you absolutely free when you register for an account, so join our community today today!.Post photos, respond to polls and access other special features.Participate in over 40 different forums and search/browse from nearly 3 million posts.As a registered Guest you will be able to: To gain full access to our forums you must register for a free account. ![]() You are currently viewing as a NON-REGISTERED guest which gives you limited access to view discussions Welcome to, a non-DIY site and the ultimate Source for HVAC Information & Knowledge Sharing for the industry professional! Here you can join over 150,000 HVAC Professionals & enthusiasts from around the world discussing all things related to HVAC/R. ![]() By continuing to use the website, you consent to our use of cookies. To learn about our use of cookies and how you can manage your cookie settings, please see our Cookie Policy. ![]() The VCCX2 Controller typically uses Refrigerant System Module(s) to control everything related to the refrigeration circuit(s), including compressors, condensers, and electronic expansion valves while also monitoring for applicable safeties and alarms.We use cookies to improve your website experience. An available EM1 Expansion Module and 12 Relay Expansion Module are available to provide additional specific I/O functions. It also has an on-board BACnet ® port for connection to an MS/TP network. The VCCX2 Controller is designed with 8 analog inputs, 4 analog outputs, 8 binary inputs and 8 relay outputs – all for specifically designed functions. The VCCX2 Controller is a configurable unit controller that can be used for Constant Air Volume, Variable Air Volume (VAV), Single Zone VAV, Make-Up Air, and Space Temperature Control of a High Percentage Outdoor Air applications.
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