AHU's Glycol coil design concern

[Andy191]

thread403-282138
Is there any experience(concern) of 4.5 degree C LAT glycol coil in AHU to share?

 

[willard3]

I'm not sure of the question you are asking.

 

[Ziggypump]

After a quick look at the linked post, here is what I know regarding glycol for cooling. If the water temperature approaches freezing, glycol will be needed.

http://www.temperaturecorporation.com/pdf/glycolconcentrationrequirements.pdf

Here's a list of concentration of glycol to water and the freezing points. If you were to have the water approach -5C, then 30% propylene would be a good choice (it gives you some wiggle room). Propylene glycol is what I prefer, but there are many options out there.

Here's something to think about; most glycol solutions come in 30% minimum. Anything less than 30% do not have the biologic contamination protection, and testing stations will be required. Most outside solutions are 30%, with some getting to 40%. Anything over 40% usually doesn't provide the protection to cost benefit. Glycol will make the water heavier and decrease the heat transfer capabilities, so sizing with glycol is the way to go, not adding glycol later, as the system might not work properly now.