Carrier 50HJ, 5 ton

[nghfam]

I need constant 1125 cfm of outdoor air does any one know or familiar with Carrier Weathermast 50HJ 5 ton unit? This is a brand new unit. The problem is overpressurization, which is what I am afraid of. If a system has an air economiser then it has to have a mean to relief excess air into the evironment without recirculation. Can anyone goes further into this problem. I don't know if this unit comes equip with power exhaust or not. All this factory components good enough to remove excess air?

 

[DrRTU]

Before applying a power a power exhaust application, you need to look at the complete system. Can you provide the design basis of the system, such as total system flow, indoor & outdoor conditions, coil loads and other exhaust flows? A HAP load would be proper way to apply the unit. 1125 CFM on a 5 ton HJ is over 50% of the nominal flow. At this high % of OA to RTN flow, it will tax the DX performance. The evaporator is not designed for high latent loads. High OA % flow may cause problems with the heating section too. Hopefully, you are not trying to use this in a 100% OA application. Is the 1125 CFM a flow fixed 100% of the time? What are you thoughts on controls and temperature /humidity requirements?

If the system application is correct, Carrier offers a couple of options for the unit that can be installed in the field. If you are being driven solely by pressure issues, then I would apply the micrometal fully modulating version rather than the end switch fixed volume.

 

[TwinScrew]

In addition to the above, if the above unit came with an economizer, then it is c/w barometric relief. (Power exhaust would be a field-installed accessory).