Control components for DHW preparation by heat exchanger

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Control components for DHW preparation by heat
exchanger
M.Sc. Jan Eric Thorsen Application Center Danfoss
A/S District Heating Controls
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Example multifunctional controller
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Why multifunctional controller ?

• One controller
• Space savings
• Reduced assembly costs
• Flexible functionality

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The optimum control concept depends on

• Primary supply condition
• Demand to control performance
• Demand to functionalities

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Primary supply conditions

Q1 T11 60-100C
T
T22 45 - 55C
dP 0.5 to 6 bar
Q2 0-0,2 l/s T21 10C
T12 15-25C
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Functionalities / Control performance

• Idle temperature (at no DHW tapping)
• DHW Circulation
• Priority function DHW/Heating

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Basic control components
Thermostatic controller
Proportional flow controller
Differential Pressure controller
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Thermostatic controller
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Thermostatic controller
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Proportional flow controller
PM controller
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Proportional flow controller with a temperature
controller serial connected
PTC controller
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Temperature controller parallel connected with
proportional controller plus dP controller
AVTI Controller
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Example AVTI controller
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Other combinations
Heating flow
T
T
Heating return
Combined therm. and prop. control (reduced stand
by temp.)
Therm. control with reduced stand by temperature
control and DHW priority
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Thermostatic variants
T
T
Therm. controller with special position of
sensor
Therm. controller with Heat Bridge
AVTB with Gemina Heat bridge
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Recommendations

• constant dP and T11, or accept seasonal
  adjusting
• free setting of stand-by temperature
• - (additional thermostatic controller)
• Preventing high temperature peaks
• - (preventing lime scale deposits)
• variable dP and T11
• comfort of high standby temperature

Proportional controller Thermostatic
controller
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Recommendations
Serial coupling Parallel coupling

• variable T11, variable dP
• control performance
• free setting of stand-by temperature
• - (additional thermostatic controller)
• variable T11, but constant dP
• control performance
• comfort of high standby temperature

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Trend within compact DHW/H sub stations

• Towards compact multifunctional controllers
• Fulfilling specific demands gt flexibility

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