aermec awhp white paper final 8-30-13

8/11/2019 Aermec AWHP White Paper Final 8-30-13

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Design considerations for commercialair-to-water heat pumps

Advantages of using air to water heat pumps

Using air to water heat pumps (AWHPs) as the primary source of heating and cooling commercialbuildings gives architects and engineers a long-term solution to designing sustainable buildings.

The heat pumps provide all the benefits of a hydronic system with the performance and energyefficiency of variable refrigerant flow (VRF) designs. Their many features include:

capability AWHPs can provide energy for a buildings cooling, heating, and domestic hot water

demands at outdoor temperatures from 5F to 105F. AWHPs can produce watertemperatures similar to condensing boilers running at their peak efficiencies,

depending on outside air temperatures.

efficiency Energy recovery options, including true simultaneous heating and cooling, result in

energy use comparable to VRF systems:

Average annual energy savings of over 40% compared to a typical boiler-plus-chillerapplication.

Installation costs are generally lower (savings are site specific).

flexibility Hydronic systems powered by heat pumps allow long-term heating and cooling

flexibility as tenant requirements and building use change. AWHPs can be the energysource for:

water-source heat pumps

fan coils radiant heating and cooling

perimeter baseboard heating central system air handlers

make-up air handlers

VAV units a combination of systems

In addition, AWHP equipment can be sized to maximize seasonal efficiency by using atrim boiler for the few hours a year of the coldest-design-or-below temperatures. VRF

systems must be sized to provide all of the heat at design conditions, meaning that theequipment is oversized for the vast majority of the heating season.

2013 Western Environmental Services Corporation. All rights reserved.

Permission granted to reproduce for personal and educational use only.


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adaptability AWHP technology adapts to existing water pipe systems. Configurations areavailable that provide both domestic hot water and heating or cooling for two-pipe fan

coil systems; provide simultaneous heating and cooling for four-pipe fan coil systems;or maintain loop temperature for water-source heat pumps systems. And as technology

changes or refrigerant requirements change, the buildings energy system can be easily

retrofitted to adapt to new technologies.

safety Hydronic systems minimize refrigerant volume and components both inside and

outside the building envelope, reducing costs and risk of leaks and eliminating the needfor leak detection systems in occupied spaces.

AWHP un it with factory-installed circulation pumps and buffer tank

AWHP basics

Two white papers on the Wescor website provide introductions to how AWHPs work, theirefficiencies, and financial comparisons:

Heat Pump Water Heater Basics

Heat Pump Water Heaters: Design Details

This white paper goes beyond the basics of heating domestic hot water and explains how to useAWHP technology to heat and cool buildings in a whole-building design.


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Basic operating designs

The following two sections provide schematics for designing basic two- and four-pipe AWHPsystems. For more involved system designs, call your local Wescor representative.

Were here to helpcall your Wescor representative for assistance when designing AWHPprojects.

Two-pipe systems

In a typical two-pipe fan coilsystem, the entire building is either in heating or cooling mode, and

seasonal change-over is usually required. (Aermec systems do not require seasonal changeovers,because the system easily changes between heating and cooling.) In two-pipe systems, the heat

pump has two separate operations, one for each mode.

In cooling mode, the heat pump can provide all the chilled water while also capturing energy from

the chilled water loop to provide energy to the domestic hot water circuit if there is a demand.

In heating mode, the heat pump can provide energy to the buildings hot water loop while also

providing energy to the domestic hot water loop.

If a building is using water source heat pumps for heating and cooling individual zones, the AWHPcan be used to maintain the loop temperature throughout the year.

Basic internal AWHP operating production for two-pipe system + DHW

Cold water production on ly to system

Bldg cooling return

Description Functioning

1Heat exchangersystem side

Evaporatorcold water produc

2Heat exchangerDHW side

not running

3Heat exchangersource side

Condenserheat exchange wi

Bldg cooling supply

33

2

1

Compressor

Compressor


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Hot water production only to system

Product ion hot water only to DHW



Condenserhot water produc


not running


Evaporatorheat exchange w

Bldg heating return

Bldg heating supply

2

1

3 3

2

1



not running


CondenserDHW production



DHW supply

DHW return

3 3


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Product ion co ld water to system and hot water to DHW

Product ion hot water to system and hot water to DHW

3

3

2

1

DHW supply

DHW return

Bldg cooling return

Bldg cooling supply



Evaporatorcold water produc




not running

3

3

2

1

DHW supply

DHW return

Bldg heat return

Bldg heat supply



Condenserhot water produc






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Four-pipe systems

Four-pipe systems can handle simultaneous and independent demands for hot and cold water, andchangeover is not required. In this configuration, the advanced microprocessor control logic

operates the unit in one of the following modes.

Cooling only

The controller activates the cold water circuit, and the heat pump acts as a traditional chillerwith energy taken from the cold water loop and sent to the outside air through the finned coils.

With dual compressors on this circuit, the unit can operate efficiently at part-load conditions.If there is a demand for domestic hot water, the energy taken from the cold water loop can be

transferred to the domestic water loop.

Heating only

The controller activates the hot water circuit, and the heat pumps evaporator coil takes energy

from the outside air and uses the condensers heat exchanger to heat the water in the hot waterloop. This is different from the usual approach of a reverse cycle heat pump, because the hot

water is produced in a different heat exchanger than the one used to produce cold water. Thisseparates the two hot-cold sections required for four-pipe systems.

Simultaneous heating and cooling

The unit operates as a water-to-water heat pump, moving energy from the cold-water circuit to

the hot-water circuit. The on-board microprocessor controller controls the evaporator andcondenser operation of each circuit and automatically changes from one configuration to the

other depending on the buildings demand. Because it uses separate circuits for the hot-waterand cold-water loops, the unit can provide partial to full cooling while at the same timeproviding partial to full heating. Having multiple circuits and compressors ensures maximum

efficiency while in part-load or full-load conditions.

Domestic hot water while heating the building system loop

A water to water heat exchanger can be added so excess energy can be transferred to thebuildings domestic water system from the building hot water system loop.


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Basic operating layout for four-pipe system

Cold water production on ly to system

Hot water production only to system

33

2

1

Description Function

1Heat exchangercooling side

Evaporacold watproducti

2Heat exchangerheating side

not runn


Condensheat excwith air

Bldg cooling return

Bldg cooling supply

Description Function


not runn


Condenshot wateproducti

3 Heat exchangersource side

Evapora

heat excwith air

Bldg heat supply

Bldg heat return

3 3

2

1


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Simultaneous hot and cold water production to system



Evaporatorcold water productio


Condenserhot water production


not running

Bldg heat supply

Bldg heat return

Bldg cooling return

Bldg cooling supply

3

3

2

1


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Why we chose Aermecs AWHPs

We are impressed with Aermec AWHPs and think you will be, too.

experience Aermec, a European company with over 1500 employees, is one of the largest HVAC

manufacturers in the world. They have over 50 years experience building HVACsystems and over 20 years building AWHPs.

quality Aermec uses axial fans, scroll compressors, and plate heat exchangers. Each unit has atleast two compressors and refrigerant circuits for redundancy and good performance

under part-load conditions.

Aermecs 46-person Research and Develop Department has six test chambers sized totest units up to 250 tons at temperatures ranging from 5F to 130F and RH from 20%

to 95%.

Aermec test chamber

certification All Aermec systems are tested and rated in-house to Eurovent standards (includingoperation during defrost conditions,included in their COP calculations) and are

certified by AHRI in the US. When an energy analysis shows a units output at designconditions, be assured that these are the equipments actual operating parameters.


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innovation Aermec units can provide simultaneous heating and cooling under full or part load

conditions and can provide free cooling when in simultaneous operation. On-boardmicroprocessor controllers provide autonomous operation with full control and

minimum management required by the building management system. Hydronic

accessories (such as pumps, buffer tanks, or a second hydronic circuit fed by adesuperheater) can be factory installed within the same footprint.

selection Aermec manufacturers a full range of AWHPs, water-to-water heat pumps, andchillers. Heat pumps for commercial applications (buildings that have independent

requirements for heating and cooling) range from 12 to 262 tons. Larger tonnage unitswith screw compressors are also available.

Aermec robotic assembly

aermec awhp white paper final 8-30-13

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