ACSC100 Supplemental HVAC Requirements/Considerations per APC App Note #109

[Anonymous user]

In case anyone out there was not already aware of it, the ACSC100 standalone cooler does require some supplementary HVAC in order for it to continue to operate.

For each ACSC unit, there must be 850cfm minimum airflow in the plenum above the ceiling (i.e.: it must be an "active" plenum). Also, the air in this plenum that reaches the inlet of the ACSC cannot exceed 105 degF (40 degC). Typically, this temperature should be cooler than that so that the unit does not shut down due to high head pressure. Bringing air in from outside for this purpose will not be applicable in all regions, in part, due to the requirement that the air be over 32 degF.

Typically, the building system will be utilized to provide this air. However, even if the active plenum above the standalone cooling unit happens to be a return air plenum, keep in mind that during the cooling season, an additional BTU load will be placed on the building comfort cooling system.

As a sidenote, when the building comfort HVAC is used to remove/cool this air, it is interesting to note that the end user will be paying to cool this air twice. Once when it is moved from their data center to the active plenum, and once more as it is cooled by the air handler for comfort cooling.

It also is important to understand the impact that this will have on the building cooling system in order to ensure that there will be enough capacity to accomodate the additional cooling load while still maintaining setpoint. This will be more significant when there are multiple ASCS standalone units installed.

We currently have two of these units installed at our location and they are working great. In terms of dropping in cooling where there is no chilled water and where options are limited as to piping out to external condensers, this is a really terrific solution and it uses very little floor space.

However, I am mentioning this because it is not at all obvious from APC's specifications on the unit itself (on the APC website) that any additional HVAC engineering must be taken into consideration when installing these units.

It took me some time to reach the right people in the APC cooling product division who were able to share this information.

There is also an application note #92 "Best Practices for Designing Data Centers
with the InfraStruXure InRow RC" that is a very valuable resource when determining where to place these units, etc. I tried to attach this document, but it was too large for the discussion forum's attachment size limit. Sadly, I do not have the URL to reach it.

At the time of my posting this, the information from APC application note #109 (as well as any link to the application note itself) still does not appear on the ASCS100 product web page:
https://www.apcc.com/resource/include/techspec_index.cfm?base_sku=ACSC100&tab=documentation

So, I am posting this info here as a reference to anyone who is planning on installing the unit so that they can have a successful experience right out of the gate by being aware of the unit's HVAC requirements in advance.

- John

[Anonymous user]

Thank you for the additional information. There is no question that you made the future implementation of the ACSC100 better for me, I'm better prepared now.

[Anonymous user · Accepted solution]

In case anyone out there was not already aware of it, the ACSC100 standalone cooler does require some supplementary HVAC in order for it to continue to operate.

For each ACSC unit, there must be 850cfm minimum airflow in the plenum above the ceiling (i.e.: it must be an "active" plenum). Also, the air in this plenum that reaches the inlet of the ACSC cannot exceed 105 degF (40 degC). Typically, this temperature should be cooler than that so that the unit does not shut down due to high head pressure. Bringing air in from outside for this purpose will not be applicable in all regions, in part, due to the requirement that the air be over 32 degF.

Typically, the building system will be utilized to provide this air. However, even if the active plenum above the standalone cooling unit happens to be a return air plenum, keep in mind that during the cooling season, an additional BTU load will be placed on the building comfort cooling system.

As a sidenote, when the building comfort HVAC is used to remove/cool this air, it is interesting to note that the end user will be paying to cool this air twice. Once when it is moved from their data center to the active plenum, and once more as it is cooled by the air handler for comfort cooling.

It also is important to understand the impact that this will have on the building cooling system in order to ensure that there will be enough capacity to accomodate the additional cooling load while still maintaining setpoint. This will be more significant when there are multiple ASCS standalone units installed.

We currently have two of these units installed at our location and they are working great. In terms of dropping in cooling where there is no chilled water and where options are limited as to piping out to external condensers, this is a really terrific solution and it uses very little floor space.

However, I am mentioning this because it is not at all obvious from APC's specifications on the unit itself (on the APC website) that any additional HVAC engineering must be taken into consideration when installing these units.

It took me some time to reach the right people in the APC cooling product division who were able to share this information.

There is also an application note #92 "Best Practices for Designing Data Centers
with the InfraStruXure InRow RC" that is a very valuable resource when determining where to place these units, etc. I tried to attach this document, but it was too large for the discussion forum's attachment size limit. Sadly, I do not have the URL to reach it.

At the time of my posting this, the information from APC application note #109 (as well as any link to the application note itself) still does not appear on the ASCS100 product web page:
https://www.apcc.com/resource/include/techspec_index.cfm?base_sku=ACSC100&tab=documentation

So, I am posting this info here as a reference to anyone who is planning on installing the unit so that they can have a successful experience right out of the gate by being aware of the unit's HVAC requirements in advance.

- John