Constant Volume system w/ perimeter heat

[lfc09]

I have an office space with a CV AHU and steam radiators at the perimeter. The question I have is what is the LAT off the preheat coil during winter months?
*Assume the perimeter heat negates my skin loss!
*My mix air temp is 61F

 

[lfc09]

To augment my question:
CV AHU = 28000 cfm
OA = 5000 cfm
Trm = 72F
Tmix = 62F
The perimeter radiation negates all my envelope loads.
What should my Tlat for winter be?
Do I even have to add heat, with the negation of my heat loss, I will actually have a heat load in the space.

 

[GMcD]

Well, what's the supply air temp you need based on the heat gains of the space? That will define whether you need to change the MAT at the AHU.

 

[mechanicaldude]

If I understand your question, you should at least have the LAT off the heating coil be 75-80 degrees F. If you don't need the AHU for heating because of the perimeter radiation then you should at least supply neutral air into the space when heating is called for. You don't want to be heating the spaces with the radiators and cooling the spaces by dumping 61 degree air in at the same time. I usually size the heating coil based on 80 degree LAT just to give some safety factor.