Snyder General McQuay

[24seven]

I have a Snyder General fed by a ammonia chiller tube and shell cooling with propylene glycol. Model RAH047CLA Serial 3ZG01749.
Space temp 76 F
Control temp 76 F
supply temp 59 F
return temp 76 F
mixed air temp 78 F
0% outside air
85 F ambient 50% humidity

My conditioned space won't reach TEMP! The office area it cools has doors opened to the hallway, over time extra rooms have been added to this space leaving some rooms with returns some with supply's and some with none. Of what I noticed on the unit the coil could be cleaned it doesn't look real dirty, but the airflow on the supply side of the coil was weak. One of the side panel access doors is also allowing some of the airflow that would otherwise go across the evaporator to spill out into ambient. I am a ammonia refrigeration tech and don't have as much experience with this stuff but the office minions are screaming. Just thought I'd put this out here and see what the HVAC gods could say. I will probably clean the two evaporator coils tomorrow and button up that exfiltration problem with the access door. Use my anemomator to verify good cfm across the coils when I am done with the clean.

[h2045]

What are the glycol entering and leaving temps?

[24seven]

glycol in 56F out at 69F

[h2045]

I would say that needs to come down. 59* discharge air off a coil with 56* entering fluid and a 13* split does not indicate to me that a dirty coil is the problem. You need to drop the entering glycol 10*. If there is a mixing valve at the AHU make sure that is functioning properly.

[24seven]

BG balancing valve at 100 percent, is that what you mean by mixing valve?

[24seven]

Maybe I need to turn it down so the glycol flows through the coil slower. The Chiller output glycol is 29*F I should get 49* easy.

[h2045]

No, you need to find out why the glycol entering the AHU is 56* when it started out at 29*?

[24seven]

Will do, thanks for your help.

[ogden]

for sure, check the airflow across the coil.that's gonna have a huge affect. gotta love how equipment is sized for a specific space and heat load and than someone wants to change rooms around and add more sqft.