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Pneumatic Control Repair or Replacement

What are pneumatic controls?  

Pneumatic controls are temperature control devices, thermostats, that use low pressure air to control the temperature in spaces served by heating and air conditioning equipment.  As the air temperature in the space varies, the thermostat varies the controlling air pressure.  The controlling air pressure then signals the heating and air conditioning equipment of the needed heating or cooling.

 Why were pneumatic controls used?

Years ago, only pneumatic controls could be used in certain heating and air conditioning applications.  Today, many other types of controls can be used instead of pneumatic controls.  However, some architects/engineers will still specify pneumatic controls because of their personal preference or installation cost considerations.

 Why do pneumatic controls fail?

The pneumatic controls contain a series of small orifices and passages.  Eventually, the orifices and passages become contaminated with oil and water.  This contamination causes the controls to become un-calibrated or “stick” and eventually completely fail.

 How do I know that the pneumatic controls are contaminated?

Your building will have uncomfortable areas.  The annual utility heating and air conditioning repair cost will be higher than normal.

 What is the source of the contaminating oil and water?

Pneumatic controls operate on low pressure air.  This air is supplied by an air compressor.  The air compressor is lubricated with oil and some oil is discharged with the compressed air.  Also when air is compressed and then cooled, water forms in the compressed air.  Both the oil and water will move with the compresses air throughout the control system.

My pneumatic control system has cleaning devices to remove the contaminating oil and water, why is my temperature control system contaminated?

Various air cleaning devices are installed in the compressed air piping to remove the oil and water.  These include various types of water/oil separators and refrigerated air dryers.  These cleaning devices require continuing maintenance.  Even with proper maintenance, some oil or water will migrate into the pneumatic control system and contaminate it.  When a cleaning device fails, massive amounts of oil and water will contaminate the control piping.

When my pneumatic controls become contaminated, what must be done to restore them to proper operation?  

The complete control system including all controllers, actuators and thermostats must be rebuilt and the air piping must be disassembled and cleaned.  The clean up must be complete.  If any portion of the control system is not replaced, rebuilt or completely cleaned, the contamination that remains will eventually invade and contaminate the entire control system.

What will it cost to clean up my pneumatic control system?

The cost of the clean up varies, but a good budget amount is $250.00 per control point.  A control point is any sensor or control actuator.  Therefore, a temperature control zone or space thermostat will usually represent three points, the thermostat cooling actuator, and heat actuator.  This means that you could count the number of thermostats and multiply the sum by three control points and $250.00.  This budget amount should include the cost of the labor and materials to flush the contamination from the piping installed in the facility.  For example, if your building is equipped with fifty variable air volume fan terminal units with terminal reheat you can budget clean up as follows:

50 thermostats X 3 control points/thermostat X $250.00 =


Can the clean up be done at a lower cost?

No, although many repair companies will quote you a lower price, it does not include a complete clean up.  Unless the clean up is complete, residual oil and water will quickly contaminate the recently cleaned components.  This means that you wasted the money that you spent on the initial clean up.

 If I spend the money for a complete clean up, how long will the clean up last before it must be done again?

The clean up was necessary because your pneumatic system was contaminated with oil and water.  If a problem develops with either the air compressor or the air cleaning devices, the pneumatic system will become contaminated again.  Then the clean up must be done again.  This could happen in one week or five years.

If the contamination of the pneumatic system cannot be avoided what can be done to minimize the clean up expense?

Our Computerized Temperature Control (CTC) system can replace all the pneumatic hardware, except the actuators.  Or “CTC” system is not subject to contamination and the actuators that will remain are not affected by the contamination.  This eliminates the future clean up cost.

Why is the “CTC” system not subject to contamination?

The “CTC” system will harmlessly pass the oil and water that normally contaminates conventional pneumatic controls.  In the future when your pneumatic system becomes contaminated, the controlling “CTC” system will not be affected.

 What is the cost of the “CTC” system?

The “CTC” system costs approximately the same as a complete clean up of the pneumatic system.

 What other benefits does the “CTC” system offer?

The “CTC” system will substantially reduce the annual utility cost.  Often, the reduction in utility cost will return the total “CTC” installation cost in less than four years.  Not only do you eliminate the future clean up cost, but you are installing the “CTC” system free because you would have spent the same amount performing a proper clean up.

 What is the annual maintenance cost of the “CTC” system?

 The “CTC” system is virtually maintenance free.  One of our largest customers, who has over sixty “CTC” systems installed, states that their annual “CTC” maintenance cost is less than 0.3% of the original “CTC” installation cost.


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