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How To Diagnose A Defective Thermostatic Expansion Valve

TXV’s

thermostatic expansion valve

Is your HVAC system acting funny lately? It might be your Thermostatic Expansion Valve.

are a crucial part of your HVAC system that are in charge of refrigerant metering. Refrigerant, produced by the chemical compound R-22, emits cool air for regulating room temperature. Refrigerant is housed in an evaporator coil. The thermostatic expansion valve measures out the proper amount of refrigerant in the evaporator valves based on needed room temperature regulation. When your TXV fails, the evaporator coil can either be flooded or starved for refrigerant. Measuring the quality of superheat emissions from the refrigerant as it leaves the evaporator.

A Defective TXV and Superheat Value

Superheat value is the measurable difference between the temperature of your HVAC’s refrigerant vapor and the refrigerant boiling point.  A thermostatic expansion valve that overfeeds the evaporation coil is made evident by lower superheat value. On the reverse. a thermostatic valve that under feeds the evaporator coil is made evident by higher superheat value. If this is the case, your txv is defective and needs to be replaced. However, before deeming your valve useless, all other possible causes of it’s malfunction should be considered. Sometimes, its bulb experiences a loss of charge.

Follow These Procedures To Determine Your TXV’s Bulb Charge

  1. If your thermostatic expansion valve has a superheat adjuster, turning the knob counterclockwise several times. If superheat value has lowered, the valve probably just needed adjusting. Turn the knob until reaching the correct value.
  2. Removing the bulb from the thermostatic expansion valve’s suction lining and assess suction pressure without it. If there is adequate refrigerant, the thermostatic expansion valve should open and suction pressure will return to where it needs to be.
  3. Sometimes there is a power assembly attached to certain thermostatic expansion valves. Remove it and asses the bulb charge. Depress the diaphragm, and if it works, the power assembly has no charge.

If You Fear You Have A Defective Thermostatic Expansion Valve, Crockett Facilities Can Help!

Crockett Facilities Services, Inc. (CFSI) is committed to helping building owners, property managers, engineers,  and facility professionals lower their operating expenses through HVAC preventive maintenance. We can develop a cost-effective, customized preventive maintenance plan for your commercial building that will provide you with peace of mind, improved comfort, and energy savings.

Click Here to Request a Quote

To learn more about the importance of HVAC Preventive Maintenance, please contact us at 202.600.2787 or sales@crockett-facilities.com. Our PM contract customers receive priority service with 24/7 emergency service in Maryland, Virginia and Washington, DC.

This entry was posted on Monday, June 20th, 2016 at . Both comments and pings are currently closed.

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