Make Up Air

[belz]

I am adding a make-up air unit to an existing apartment building. The building has a 2-pipe hydronic system (Simultaneous cooling/heating is not avaliable). How can I condition the outside air without subcooling the cooridor served? There is virtually no load in the corridor. I am considering controlling to corridor space temperature (dry bulb) while watching corridor relative humidity. If the relative humidity exceeds a maximum setpoint (adjustable) I will override the space dry bulb control and subcool the space until an acceptable relative humidity is achieved. Electric or hydronic reheat is not avaliable. Also, would you use the ASHRAE Fundamentals Cooling DB/MWB or DP/MDB weather data for your outdoor condtions?

 

[quark]

First of all, there should be some data can be analyzed. What is the area DB and WB, what is ambient DB and WB, flow rate, whether your system is once through etc. Sensible cooling of OA will definitely increase its RH. Your idea is ok but will you have two coils for this?

If your ambience is humid, I will prefer 2% value of WB/MCDB. Otherwise it is 1% of DB/MCWB. This is basically a designer's choice and depends on whether he likes to walk on a tight rope or not.

Regards,