How can "Air Cooled-ACRD" units to be switched ON automatically, when "Chilled Water-ACRC" units turn OFF?

[BillP]

Hello everyone!

I got some project, with already bought units and plan how it should work. I need Your help, because don't have much of experience in this.

I have ACRC502, ACRC301S, ACRD502, ACRD101. I need "Air Cooled" units to be switched ON automatically, when "Chilled Water" units turn OFF. How can it be done? What are possible different configuration? what kind of extra units should be used, if needed?

[BillP]

Hello 

     To accomplish this I am assuming that you are only looking to turn on the air cooled units when something happens to the chiller and the chilled water units are no longer able to maintain room temperature. If you are looking for a different configuration then this, please let us know. There is no direct communication between the air cool and chilled water units. The Air cooled (ACRD101 and ACRD502) units will need to be controlled but the remote off contacts (see page 26 of the install manual for wiring). These will need to be wired to a relay or switch to keep these units off normally. The relay/switch will need to be controlled by either the chiller or the chilled water units. I would recommend the chiller be used as the control. This is to prevent an error on one of the chilled water units from mistaking turning on the Air cooled units. The relay/switch could also be controlled by a temperature sensor (or other sensor) in the room as well. When the chiller goes down or the temperature in the room got to high, the relay/switch would flip and allow the Air cooled units to turn on to cool the room.

     The Air cooled units will show an alarm of "On standby, input contact fault exists." while the chilled water units are working. You can use the Chilled water unit's output relay to control the relay. You will need to make sure the relay can be controlled by dry contacts. The unit’s output relay is just a set of dry contacts. You will also need to configure the output relay on the unit to only alarm on critical alarms so the unit does not swap over on a noncritical alarm. This can be done through the front screen. Again I would recommend seeing if the chiller can send a signal to control the relay instead of the chilled water units or to use an external sensor. If you need any clarification on this or have any more questions please let reply or give us a call. Please check our website www.apc.com and the contact link at the bottom right to find the appropriate number for your country.

Thank you

[BillP]

Hello!

     Yes, I was looking to turn on the air cooled units when something happens to the chiller and the chilled water units are no longer able to maintain room temperature. I read out that there is no direct communication between the air cool and chilled water units by A-Link. If Air cooled (ACRD101 and ACRD502) units can be controlled but the remote off contacts, then it suits my purpose.

     Still, I have some questions. As I read at page 32 of InRow RD Installation manual (regarding to ACRD502), Customer input +  is used for remote shutdown of the InRow RD. Voltage is applied from the internal power supply or by using an external power supply, so exactly what input should be used to start InRow?

     The same story with ACRD101, in InRow RD 10kW Air Cooled Installation at page 25, I can see Shutdown input contacts and alarm output contacts, so I have my question again, is there any kind of input, that can start up InRow and shut it down?

[BillP]

Hello.

     There is no input to start the InRow unit. The process is to keep the unit in remote shutdown until the unit is needed. When you release the remote shutdown the unit will start cooling provided it sees a demand for cooling (this depends on the setpoint that the unit is configured to maintain. These are set under the group setpoints menu on the unit).  The only other thing you will need to do is to turn the unit from "standby" to "on" through the front screen before you apply the remote shutdown. This will cause the unit to maintain the setpoint that it was set to, once the remote shutdown is released. I hope this clarifies your question. Let us know if it does not.

Thank you

[BillP]

Hello.

     Regarding to theme above, can I use relays and 12/24 Vdc, to complete this connections? In manuals it's written "Customer input + (12–30 Vac/Vdc, 24 Vdc @ 11 mA)"  and "Supply 12 Vdc (current limit: 20 mA)"/"Supply 24 Vdc (current limit: 20 mA)", is it okey to give power from Supply to Customer input, wont it be over-current?

[BillP · Accepted solution]

Hello.

For the input contact, it will need +12 or +24 volts DC. You can either use the unit's +12 or +24 volts or supply the voltage from another source. The best place to see the wiring of the input contact is on page 29 of the ACRD100 installation manual. This is the same wiring for all the InRow units for the input contact.

For the output contact, this is just a dry contact. No voltage is used.

Thank you