Colmac Coil heat pipe coils (heat exchangers) are designed to efficiently transfer heat from a warm air stream to a colder one. Heat pipe coils are constructed of multiple individually sealed heat pipes evacuated and charged with a volatile refrigerant. The heat pipe coil is partitioned in the center so that the warm air stream passes over one end (the evaporating end) of the heat pipes and a second cold air stream passes over the other end (the condensing end). As the refrigerant continuously evaporates and condenses within each individual heat pipe tube, heat is transferred between the two air streams with very high thermal effectiveness. Heat pipe coils are simple passive devices, with no moving parts, pumps, or external piping. Compared to heat wheels which rotate a thermal media through the airstreams to transfer heat, heat pipe coils offer the following advantages:
• No moving parts to maintain or replace 
• The media (refrigerant) never "wears out" or becomes fouled, requiring replacement
• Warm and cold airstreams never mix (become "cross contaminated")
Colmac Coil heat pipe coils can be designed for HVAC or industrial process applications covering a wide range of temperatures. Because the heat pipes use volatile refrigerants as working fluids, there is no risk of freeze damage as there is with water or glycol run-around loop systems.
Air-to-air Heat Recovery:
Any building or industrial process that exhausts air must bring in an equal amount of replacement ambient air. Heat pipes offer building and process designers a passive technology which effectively recovers a significant amount (typically 60 to 70%) of the heat energy in the exhaust air stream. Heat pipe coils can be designed to pre-cool supply air in summer months and equally as effectively pre-heat supply air in winter months in a single unit. Heat pipe coils can be effectively applied to recover heat from laboratory building exhaust where cross contamination to the supply air is unacceptable. Heat recovery in buildings having large populations of individuals who smoke cigarettes, such as casinos, is not possible using heat wheels as the media quickly becomes fouled with the cigarette smoke and tar. Heat pipe coils are an excellent heat recovery solution for casinos since the heat pipes continue to effectively recover heat even in smoky or dirty airstreams.
Wrap-Around (Enhanced Dehumidification with Free Reheat):
Whenever it is desirable to dehumidify an airstream using mechanical refrigeration, wrap-around heat pipe coils can be used to remove sensible heat from an airstream prior to cooling and dehumidifying through a conventional DX evaporator or chilled water coil. The wrap-around heat pipe coil is simply installed so that one end pre-cools the air entering the cooling coil, while the other end re-heats the air leaving the cooling coil. The heat pipe coil is manufactured by Colmac Coil in a "U" shape which "wraps around" the cooling coil. The water removal capacity of a mechanical dehumidifier designed to operate with air having a nominal relative humidity of 50% can literally be doubled simply by adding a wrap-around heat pipe to the system. The wrap-around heat pipe coil also effectively reheats air leaving the cooling coil in fresh air cooling systems. Added to the cooling coil of a fresh air handling unit (FAHU), a Colmac Coil wrap-around heat pipe coil passively reheats the cooled and dehumidified fresh air with no need for the addition of a hot water coil or electric resistance for reheat. This is an important feature of wrap-around heat pipe coils which inherently enhances indoor air quality (IAQ) in occupied buildings.
Hermetic Heat Rejection:
Colmac Coil heat pipe coils can be used to reject heat from spaces which cannot be contaminated with ambient air or other particulates. Typical applications include heat rejection from high voltage VFD drives and electronic switch gear.
CoilPro Selection Software:
Colmac Coil engineers have developed a proprietary software program, CoilPro, to allow qualified users the ability to accurately estimate thermal performance for a wide range of heat pipe configurations and applications: 
• Imbalanced exhaust and supply airflows
• Varying fin spacing for exhaust and supply
• Varying fin materials for exhaust and supply
• Either waffle (configured) or flat plate fins
• Heat Recovery or Wrap-Around heat pipe configurations
The software also allows the user to quickly obtain a price and dimensional specification drawing for the heat pipe selected. The program is browser driven and runs online. Updates are automatic and so do not require that the user waste time downloading and reinstalling the program.
Features and Options:
• Standard heat pipe tubes (5/8") for small to medium capacities
• Large diameter heat pipe tubes (7/8" and 1") for high capacities
• Wide range of working fluids suitable for low or high working temperatures
• Aluminum and copper tube construction
• Corrosion resistant construction and coatings
• Tilt capacity control for low ambient supply air temperatures
RESOURCES:
IOM - HEAT PIPES
PRODUCT FLYER - HEAT PIPE COILS
PRODUCT FLYER - HEAT PIPES FOR HEAT RECOVERY