Compact units

ECU	ETA ACCU	ETA PAC

ETA ACCU

 
Air handling with high level of heat and moisture recovery

Increasingly high demands are constantly being made of modern buildings in terms of air quality and economics. Against a background of rising energy prices, the building shell is being increasingly insulated and sealed. Consequently, in new purpose built buildings the heat transmission load is often well below that of the ventilation heat requirement. Energy-saving air handling optimised to particular requirements is thus one of the most important planning functions in building technology. The running costs of the building are largely determined by this factor. At the same time, the user‘s sensitivity to air quality is increasing and importance is placed on avoiding the harmful effects of buildings on people (key word: sick building syndrome). As a result, considerable significance attaches to the exchange and conditioning of the air in the building. That’s why the different heat recovery systems available in the air-handling market are widely used in modern buildings. In many applications the requirement is for the highest efficient recovery of a combination of sensible and latent  heat. Depending on the building‘s use, it is thus possible:

• to reduce to a very large extent the energy required to heat the building („low energy house“)
• to reduce considerably the size of and thus the capital expenditure on the heating and cooling system for the building
• generally to dispense with energy consum-ing air humidification in winter

EUROCLIMA® has developed the ETA ACCU unit in response to these requirements. It represents the current state of the art in heat recovery units. The double heat accumulator, through which the intake and exhaust air flow alternately, together with the intelligent control system result in exceedingly high heat recovery values. The EUROCLIMA®-ETA ACCU ventilation unit offers the following benefits:

• heat efficiency above 90%, moisture
• recovery > 75% through highly sensitive
• accumulator blocks
• reduced capital expenditure on heating, hu-midification and possibly cooling
• short payback period due to large energy savings
• additional air humidification normally not even required
• intelligent control system incorporated into the unit: unit automatically selects the best mode of operation  depending on the state of the outside and interior air
• air filtering in all modes of operation

In addition the ETA ACCU Cool offers

• efficient refrigeration circuit with 2 Scroll-compressors
• environmentally friendly coolant R407C

Winter mode

Maximum recovery of the heat and moisture in the exhaust air is required at low outside temperatures. The front accumulator is heated by the hot exhaust air and the moisture contained in it is stored in the plates. At the same time the cold outside air is heated and humidified in the rear accumulator. After a split-second interval the process is switched over and repeated in the opposite direction. Depending on the energy efficiency of the building, a subsequent hot water heater (optional) can be used to heat the intake air to the required temperature. It is not generally necessary to humidify the intake air.
The self-regulating effect of the moisture recovery is generally enough to provide an acceptable level of humidity in the air.

Summer mode

The hot outside air which passes over the accumulator is cooled by heat recovery from the exhaust air. For buildings with high internal heat loads, the cooling circuit integrated into the design of the ETA ACCU Cool provides additional mechanical cooling. The cooling unit can thus be made correspondingly smaller due to the cold recovery via the accumulator.

Modulating Operation

At the need for heating declines, first the hot water heating (if present) is lowered and then the heat recovery is gradually reduced to zero. This is done via the switching frequency of the charging/discharging process. Thus in summer the switching frequency is modulated to produce the required cooling output. If the outside temperature is higher than the required intake air temperature, the accumulators begin modulating operation. If the required intake air temperature is still too high even at maximum switching frequency the optional multi-stage refrigeration circuit will be activated.

Free overnight cooling

If required, the additional function „free overnight cooling“, which cools the building overnight with colder outside air by enthalpy comparison, can be activated in summer operation. In this case there is no flap switching via the accumulators.

Technical specification ETA ACCU

Unit casing in self-supporting modules (panels) with integrated base frame and continuous profile sections on the upper edges of the unit. Casing walls of the modules completely smooth on the inside and outside. Internationally patented – snapin joint construction of the inner and outer skins of the double-skin panel, 50mm thick panel enclosing a layer of insulation for optimal acoustic attenuation and thermal insulation. The housing has been tested and is certified following the EUROVENT Standard, EN 13053 and EN 1886 with the following results:

• Mechanical strength: class D1
• Air tightness: –400Pa class L1
• Air tightness: +700Pa class L1
• Thermal transmittance: class T4
• Thermal bridging factor: class TB2
• T2 / TB2 (optional)

Panel design

Inner skin: 1,00 mm galvanized steel; Outer skin: 0,7 mm galvanized steel, in addition exterior is plastic coated for corrosion protection and optical appearance. Coating Type A47SME, colour white, coating thickness ca. 150 μm, base frame in galvanised sheet steel. Large access doors in the same thickness as the panel walls, with aluminium door frames; door panel design as panel design; adjustable hinges; corner-welded, ageing resistant profiled rubber seals, safety locks; Supply and return air fans; Energy optimised plug fan for operation without casing due to special blade arrangement for high efficiency and good acoustic performance with 6 backwards-curved blades; Powder coated for surface protection. Direct drive of radial fans. No V-belt losses and no V-belt wear; Serial electro magnetic combaribility in accordance with EN 55011; three-phase TEFC motor, rotational speed control via frequency converter.Air filters; Air filters in exhaust air and outside air, quality class G4 and F7 pressure differential switch for control of filter maintenance.

Heat accumulator

The highly sensitive double heat accumulator recovers latent and sensible heat from the exhaust air. The outside air is thus pre-heated or pre-cooled at a thermal efficiencies of up to > 90%. If the outside air is cold, moisture is transferred at efficiencies up to over 75%. In summer, the outside air is cooled using the lower temperature of the exhaust air and – where possible – free overnight cooling. The accumulators are alternatively charged and discharged and switched over by the constrained split-second commutation of the damper system. These are activated by a central transmission motor.
The switching frequency is used to control the capacity.

Refrigeration circuit and cooling coil (ETA ACCU Cool)

Cooling section with 2- or 3-stage Scroll-compressors, intake gas cooled, Cu/Alu air-cooled condenser, Cu/Alu direct evaporator and coated fins. Unit evacuated and filled with environmentally friendly coolant R407C ready for operation. Coolant compressor on vibration-damper, unit with refrigerant drier and inspection window, thermostatic expansion valve, monitoring of evaporation pressure and condensation pressure. Plastic fin droplet separator, galvanised steel casing.

Heating section

Hot water heating coil with aluminium fins, threaded headers on the connection side for connection to tubing and mounting of the 3-way valve. Heat exchanger data certified in accordance with EUROVENT Rating Standard 6/C/005-2009

Electronic control

The electric panel including on/off-switch, fuses and overload protection for all components is installed inside the unit. All the terminals for electric supply and for connection of additional components on site are included. Programmable control device with graphic display and one-button operation; interface PGU, manual device for emergency actuation, modem-moduls for remote control.

Control features

• Different user levels
• Automatic choice of operation mode
• Return air temperature
• Supply and exhaust air fan
• Heat accumulator
• Damper actuation
• Week watch
• Day watch
• System error
• Filter control
• Frost protection
• Control of compressor
• Exit for circulating pump of heating coil

Optional accessories

• Modem integrated into the control unit for remote maintenance and data interrogation
• External control panel for installation in an external main distributor. Possibility of adjusting all set values and interrogating all actual values.
• Flexible connectors for intake air, exhaust air, outside air and onward air.
• 3-way-mixer for hot water pump heater.
• Start-up and commissioning of the unit.
• Maintenance: annual servicing of the unit in accordance with the manufacturer‘s mainte-nance instructions.