Chiller Systems – Restart during winter conditions

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This article covers chiller restart procedures when your air cooled process chiller has been off line or operating under low process loads during cold weather that can produce snow or ice.

Restart of an air cooled condenser during the winter can be a challenge as snow and ice tends to be very opportunistic. During no (or low) load conditions, some basic system checks must be performed to restart your chiller to assure reliable operation.

Important Steps:

1. Glycol: If your climate is susceptible to freeze, verify your glycol free point. Legacy recommends that you maintain glycol concentrations to protect your system at all times. Below, you will find a link to an article on how to setup your chiller to run glycol.

2. Fan blades: Most Legacy chiller air cooled condensers are “updraft”. At the top of your chiller, you will see fan protection grille(s) and under those grille(s) are your condenser fan blade(s). With the power OFF, using a long thin blade screw driver, give the blade(s) a spin. In some cases, prevailing winds will cause the fans to spin on their own so if they are spinning, you are OK. If your fan blade will not spin, you will need to investigate further and repair as needed.

If your system is equipped with and integrated or retrofit Economizer system you will need to perform the same fan checks.

Starting your fan motor(s) with a seized fan blade will damage your fan and possibly blow fuses. Such instances are NOT covered under Legacy’s Limited Warranty.

3. Electrical system: On new installations it is common for service personnel to leave cabinet doors open exposing the chillers electrical and control systems to the elements. Before restart, look over all electrical connections and make sure the electrical compartment door is secure before turning your power back on. It is also advisable to check all other cabinet panels to make sure they are on and secure.

4. Micro processor alarms: Until your chiller system gets close to full design load, it is common to receive the following micro processor alarms:

A. LTA: This is a manual reset alarm. You are most likely getting this alarm since your fluid temp is blow the LTA set-point. You may need to press (and hold for 1 second) to resent this alarm. If you continue to get this alarm after re-setting a few times, wait until you get more load on the chiller and/or investigate further.

B. Lo Flo: If your process fluid temp is below design temp or if you have added glycol since initial system commissioning adjustments Lo Flow alarms are to be expected. If your process is below temp, wait until you at temp and you should see this alarm subside. If you have added glycol you may need to recalibrate the chillers differential pressure flow safety switch. Below you will find a link to a more detailed article covering this important component.

HTA: In come cases customers have turned on their load before the chiller. The HTA alarm is auto reset and has no effect on the cooling operation of the chiller unlike the LTA alarm that is manual reset. Should you see an HTA alarm, simply allow the chillers compressor to run for up to 60 mins. If the HTA has not cleared after 60 mins of compressor operation, you will need to investigate further.

Legacy Chiller Systems offers fee based Factory commissioning services. ALL Legacy systems should be commissioning by a qualified prior to putting your chiller into service. For more information on factor commission services, contact Legacy Chillers Systems at 877-988-5464.

All air cooled condenser chiller system with or without Economizers.

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