Description
ESES
Air-Source
Benefits/Drawbacks
 
 
 
 
Outdoor condenser required
No
Yes
DX loops are buried in the ground
Defrost cycle
No
Yes
ESES DX does not require defrost cycles
Air temperature affects capacity
No
Yes
ESES DX is buried in a stable environment
Air temperature affects efficiency
No
Yes
ESES DX is buried in a stable environment
Supplemental heat requires
Yes
Yes
ESES looses less capacity
Less mechanical moving parts
Yes
No
ESES has fewer parts to fail
Less maintenance required
Yes
No
Less parts = less maintenance
Low noise levels
Yes
No
ESES is much quieter during operation
Water heating capable
Yes
No
Can provide domestic hot water
De-superheater
Yes
No
Provides free hot water in Summer
Radiant floor heating capable
Yes
No
Available for radiant heating applications
Energy Rating
Excellent
Moderate
ESES is 30-70% more efficient
Life expectancy
25+ years
10-12-Years
Geothermal systems last longer
Parts warranty
10-years
1-10-Years
Factory warranty
Labor warranty
10-years
0-90 Days
Factory warranty
Compressor warranty
10-Years
5-10-Years
Factory warranty
Condenser coil/loop warranty
55-Years
1-10-Years
Factory warranty
Installation cost
High
Moderate
ESES DX is 150-200% more expensive
ESES DX Geothermal vs. Air-source Systems
System Design

The first step in any HVAC design is the load calculation. This is one of the most important steps as it is the
foundation for the system. Some contractors rely on “rules of thumb” or “experience” instead of performing an
accurate load calculation. This is wrong and an unacceptable practice. If the contractor does not perform the load
calculation, do not do business with them! After the load calculation has been performed, then the system can be
sized to meet the loads of the structure and the duct system can be designed. The designs must be in accordance
with Air Conditioning Contractors of America [ACCA] standards. Choose the system that meets the load requirements.
Slight overages are OK, but the system should be sized as close as possible to the loads.

Air Distribution System

Both types of systems need an air distribution system. Air has to move across a heat exchanger [called the
evaporator coil] to transfer heat energy. Depending on the mode of operation, heat energy is transferred into or
removed from the air stream through the refrigeration process. The more heat energy that is transferred, the higher
the system capacity. The evaporator coils are generally constructed of highly conductive copper refrigerant tubes
with bonded aluminum fins. The aluminum fins are thinner, have a high conductive capacity and increase the heat
transfer area. Once the heat energy is transferred, it is distributed by the duct system throughout the structure.

There are two types of heat energy transferred by the heat pump: sensible and latent heat.

Sensible heat is heat energy you can feel and is easily read by a thermometer. The warm air you feel in the winter is
all sensible heat and the cool air you feel in the summer is the absence of sensible heat.  

Latent heat is a little different. Latent heat is the moisture related heat in the air. The moisture in the air is in a vapor
form and contains a lot of heat. By reducing moisture in the structure during the cooling mode, you reduce heat. I’ll
explain. A British Thermal Unit [Btu] is a measurement of heat energy. It is defined as the amount of heat required to
raise one pound of water one degree Fahrenheit. Water becomes a liquid at 32° F and boils at 212° F [at sea level].
To raise that pound of water from 32°F to 212°F takes 180 Btu’s of heat energy. To change that same pound of
water from 212° F water to 212° F steam, it takes another 970 Btu’s of heat energy. This is known as the “latent heat
of vaporization”. Changing the water to steam [vapor] requires a phase change, which requires more energy. So by
removing moisture from the air, you in fact are removing heat. By removing one gallon of moisture, you remove more
than 7,700 Btu’s of heat energy. The cooling system must be sized to meet this load or a host of other issues will
arise.  


Refrigeration System

The heart of both types of systems is the compressor. The compressor pumps the refrigerant through the refrigerant
circuit carrying heat energy. A compressor’s heat transfer capacity is rated in a measurement called a ton. There are
12,000 Btu’s in a ton of refrigeration capacity. Therefore, a 3.0-ton compressor is able to produce 36,000 Btu’s of
heat transfer capacity. The system design determines how efficiently heat energy is transferred. This is where the
Geo Direct DX system and air-source systems part company.

In an air-source system, the refrigerant is circulated through a “condenser coil”. The condenser coil is typically a
copper/aluminum or aluminum design. This coil transfers heat energy from the refrigerant during the cooling cycle
and picks up heat energy during the heating cycle. The 4-way valve or “reversing” valve determines which mode of
operation occurs. Typically, when the valve is energized, the system is in the cooling mode. When it is de-energized, it
is in the heating mode. This valve directs the refrigerant in opposite circulation patterns to transfer heat energy.  

The air-source system uses a fan to move air across the condenser coil to transfer energy, unlike the Geo Direct DX
system. Since the Geo Direct loops are in direct contact with its heat sink, no fan is needed reducing operation noise.
The air source system has 3 capacity ratings, except for 2 speed units which have 6:

  1. High Speed cooling [95° F outdoor temperature]
  2. Low Speed cooling [95° F outdoor temperature]
  3. High speed heating [47° F outdoor temperature]
  4. Low speed heating [47° F outdoor temperature]
  5. High speed heating [17° F outdoor temperature]
  6. Low speed heating [17° F outdoor temperature]

Air conditioning capacities for air-source systems are tested at 95° F outdoor ambient temperatures. Heating
capacities are tested at 47° F [high capacity] and 17° F [low capacity] outdoor ambient temperatures. Why? Because
there is less heat available in the air at colder temperatures reducing the systems ability to transfer heat energy. The
Geo Direct DX system loops are installed in a more stable environment, so it does not loose capacity like the air-
source models. Plus, when the outdoor temperature drops below 45° F, moisture in the air begins to freeze on the air-
source condenser coil requiring a defrost cycle to "melt" the frost/ice from the system. Without this defrost cycle, the
system would loose nearly all of its heat transfer ability. This cycle increases stress imposed on the system because it
is switching from heating to air conditioning to melt the frost/ice, then back to heating after the defrost cycle is
complete. Reversing the refrigerant flow causes surges in the system, as evident by the increase in operating noise
during the defrost cycle. This wears on the system and its components. Every time a defrost cycle is initiated, the
auxiliary heat strips are turned on to temper the air during the defrost cycle. This increases operation cost and
reduces the systems energy efficiency. This is important in areas where snow and ice occur.   Air-source heat pumps
will freeze up in a matter of minutes when freezing precipitation is present adding to energy consumption and system
stress. The Geo Direct system loops are installed in the ground where freezing conditions do not exist and do not
require defrost cycles.

Summary

The Geo Direct DX system has many advantages over the air-source systems. Quieter operation, higher efficiencies,
more than twice the life expectancy, fewer parts, less maintenance and the compressor section can be installed
indoors. The systems are much smaller than the air-source models which continue to increase in size due to larger
coil surface requirements for higher efficiencies. Plus, the Geo Direct system offers incredible comfort levels
compared to the air-source system.
Geothermal Heat Pump Facts:
ESES Geo Direct DX vs. Air-source