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[EnergyPlus_Support] Re: Learn from my mistakes - EMS to avoid DX coil freeze - bad implementation

I agree with Dr Li. 

To re-iterate my first statement:"Because cold climates should a) have a freeze protection heating coil to avoid air at minus deg C temperatures from entering any system, regardless."

This should not be done to stop warnings. This should be a temporary work around (until a freeze protection is properly integrated into the current models) to ensure that the dx system does not try to operate when receiving ice cold air in the case of the frost protector heater malfunctioning, or if the real system does not have this pre-heater. 

In that respect I like how the chilled ceilings can be programed with condensate protection (with margin of safety) by turning off when condensation is predicted. If that is how real systems work, then that is how we should model them.

Brent, made a good point about the condenser coils...I'll have to research that one to see what the typical solution to this problem is. Dr. Li pointed out that the defrost cycle will kick in. This I think means that the unit can however no longer cool. The coils on the roof are packed in ice and snow, but the data center still needs cooling...what do you do? Add more glycol?

Just because I know how much Dr. Li hates ASHRAE and LEED I'm going to ask what ASHRAE has to say about, pre-heating coils (only since it's weekend and my 90.1 standard is on my desk in the office...I don't sleep with it under my pillow). How does one implement pre-heating coils in the case where your proposed case has no mechanical system and you're forced to model the baseline systems into your proposed model...can you use pre-heaters?





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