Overview
The TRICOIL® system changes the sensible heat factor of an air conditioning unit so that the unit can match the sensible heat factor of the occupied space. This method has been successfully used for over 20 years. Two common objections have been raised:
- The three-coil arrangement takes up more room than traditional methods.
- The system requires a pump that consumes power and occupies space in the equipment room.
This paper describes two new inventions that address both concerns — resulting in a system that is smaller, less expensive to install, and less expensive to operate.
Invention 1 — Eliminating the Pump
The traditional TRICOIL® system uses a small fractional-horsepower pump to circulate water between the precooling and reheat coils. The new pumpless configuration replaces that dedicated pump by using the pressure available in the chilled water supply itself as the driving force to circulate water through the run-around piping.
This approach also allows the same chilled water flow to pass through each of the cooling coils, enabling both coils to share the primary cooling duty. Sharing the cooling load reduces the total heat exchange surface required, which in turn:
- Reduces air-side pressure loss across the coil bank.
- Reduces the total cost of the coils themselves, since less heat-transfer surface is needed.
- Further lowers operating costs.
Precooling coil → Primary cooling coil → Reheat coil, with dedicated circulating pump.
(Diagram to be added)
Same three-coil layout; chilled water supply pressure replaces the dedicated pump — no pump, no pump electrical, reduced piping.
(Diagram to be added)
Invention 2 — The Combo Coil
The second innovation combines the two cooling coils — the precooling coil and the primary cooling coil — into a single, specially circuited coil assembly: the Combo Coil.
In the traditional three-coil arrangement, incoming air passes first through a precooling coil, then through the primary cooling coil, then through the reheat coil. The Combo Coil merges the first two coils into one unit. The circuiting inside the coil separates the precooling and primary cooling functions hydraulically while sharing the same coil cabinet and air-side face area.
Combo Coil (precooling + primary cooling circuits combined) → Reheat coil. Smaller footprint, fewer connections, reduced equipment room space.
(Diagram to be added)
Internal circuiting detail of the new single-coil design showing how precooling and primary cooling duties are hydraulically separated within a single coil casing.
(Detail diagram to be added)
Benefits Summary
No Dedicated Pump
Chilled water supply pressure drives circulation — eliminates pump hardware, electrical work, and maintenance.
Smaller Footprint
Combining two coils into one reduces the length of the air handling unit and the equipment room space required.
Lower First Cost
Fewer coils, no pump, less piping, and a smaller air handler all reduce the installed cost of the system.
Lower Operating Cost
Reduced air-side pressure loss and elimination of pump power consumption lower ongoing energy costs.
Shared Cooling Duty
Common chilled water flow through both circuits enables each to share the primary cooling load — requiring less total coil surface.
Proven TRICOIL® Foundation
Built on the same recuperative principle that has been successfully installed for over 20 years across hundreds of applications.
Inventor
Kenneth L. Eiermann, PE, is the inventor of the TRICOIL® system and holder of multiple US patents on recuperative dehumidification technology. He is founder of Sensible Equipment Company, Inc. and Eiermann Engineering, Inc., Orlando, Florida.
For engineering inquiries: kle@tricoil.com · (407) 296-8068