Ask Rick: Control for Wrap Around Heat Pipes

Ask Rick Question:  I am considering putting in a wrap around heat pipe to reduce cooling tonnage and provide reheat.  Is there a way that I can control the heat pipe to reduce reheat?


Wrap Around Heat PipeThe Wrap Around Heat Pipe (or Dehumidification Heat Pipe) is used in lots of applications where reheat is typically used.  They are usually applied as passive devices designed to match the system requirements.  Modulation of the cooling coil alone is often adequate for control.  In some instances the need for maximum sensible cooling overrides the need for humidity control.   Because of this, it is necessary to temporarily lower the effectiveness of the heat pipe.  

We prefer controlling Wrap Around Heat Pipes with Electrically Operated Solenoid Valves.  The, normally open,  electric solenoid valves are installed in the liquid return lines of the individual heat pipe circuits. The number of valves needed is determined by the size of the heat pipe, the number of rows, and the degree of control desired. 

We don’t typically provide controls for all circuits.  That’s too costly and too large a range of control.  It’s typical to control half the circuits on a dehumidification heat pipe.  So the total heat pipe system would have a mix of controlled and uncontrolled circuits on the heat pipe.

Wrap Around Heat Pipe with Solenoids

Wrap Around Heat Pipe with Solenoids

Other Notes on Applying Solenoid Valve Control:

  • Each control valve is operated by either a 24 VAC or 115 VAC digital output (DO) from The Building Automation System. Valves are usually controlled in ganged stages to provide multi-step operation of the heat pipe.

  • 30 Watts of electrical power is needed to operate each valve

  • The size of the solenoids adds depth to the heat pipe center section.  Make sure to consider this in the system design.

Related Materials:
Wrap Around Heat Pipe Control from Heat Pipe Technology
Heat Pipe Technology – DHP with Solenoids- Specification from Heat Pipe Technology

More questions on controlling wrap around heat pipes;  askRick?

Related Blog Posts: 
Wrap Around Heat Pipe | How does a wrap around heat pipe work?
Heat Pipe for HVAC Systems | Heat Pipe Theory


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