Freeze Protection & Economizers BMS Training for HVAC Technician

This was one of our December trainings for our technicians. In this I discuss BMS controls for freeze protection and economizer controls and functions in commercial buildings HVAC.

Support the channel through,

[jasonjohnsonHVAC]

Then you have systems that are designed to run in cold outdoor temps. I have several buildings i service ( industrial applications ) where the chillers shut down, diverting valves actuate, and then the BMS switches to the dry coolers for operation. Or the closed loop tower switches to winter mode and the fan runs only. The sump/ basin is emptied. They have basin heaters but they are barely ever running. Im in Buffalo, NY. Most our towers are dry in the winter.

Lots of our AHU here also have face and bypass dampers on them. It works pretty well for maintaining set point/ humidification. Most of our AHU'S have both a cooling and heating hydronic coils in them. Then there are quite a few with DX cooling and hydronic heating coils too. I love the variety of stuff i come across on this side of the trade. I have to have my thinking cap on and thats when i feel i perform my best.

[djupton]

Averaging sensor is what you were looking for.. Also, h2o is always in at the bottom and out at the top. Easy to pick up on these from the couch! 😜 I too am in Texas, just a little south of you. Keep up the good work man!

[cariocadenyc]

We are in the northeast. Systems here are built for all four seasons. Its typical for AHUs to have full airside econonmizers and sometimes waterside economizers. In the shoulder seasons like spring and fall, systems will swicthover between summer and winter modes at morning and night due to OA conditions. The BMS is critical and must be programmed correctly to operate in all these different modes.

[cariocadenyc]

Freezestat capillary. The head of the freezestat always must be above the capillary. Also the capillary must be horizontally strung out. The coldest one foot section of the capillary will trip it if the temperature drops below the setting. The freezestat trip shuts down both supply and return fans. CHW valve should open. We have a client that likes to enable the return fan and run it at half speed to pump warmer return air into the plenum and thereby keeping the coil warm.