coil freezing

[mech4321]

I want to install a new split system York, 10 tons, 2 stages with air bybass. Do I need to install a temperature sensor in the supply to prevent coil freezing.

 

[ChasBean1]

You shouldn't need a freezestat for the coil itself, but if you have downstream coils with hot water reheat (or even if not), you might want a low temperature safety in the discharge section. Unless you're referring to preventing coil refrigerant ice-up, so correct me if I'm off base...

 

[BM4BRANES]

Hot gas bypass would be the preferred method to manage part load conditions for vav type applications rather than on/off controls. HGBP will cost more up front but will not beat a compressor to death prematurely like the freeze stat method.

 

[BronYrAur]

You mentioned air bypass. Is this for a VVT system? You need to be careful not to let your air return temp get too low if you are bypassing too much.

 

[murray11]

Hi, If you are worried about the coil iceing because of low airflow across the coil. Trane makes a control called a froststat which is just a low temp control switch. It has a cap tube you bury in the fins of the coil. If the coil starts to ice it opens the switch. Wire your cooling stages through the switch and they shut down until the ice condition is gone. (Temporary Defrost)Just a thought

 

[cdxx139]

To prevent DX coil freezeup, you need to maintain a minimum flow across the coil. If it is a VAV system, then a VVT design will prevent that (as mentioned). Be careful of Hot Gas Bypass. It is frowned upon due to the energy waste, and may not be allowed (see you local energy code). To answer your question, I have never used or seen a freezestat on a DX coil.

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