Technical data

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6.2.14 EXPLANATION OF THE PARAMETERS FOR ENERGY AND
COST OPTIMIZATION OF THE HYBRID SYSTEM (CONTROL
STRATEGY)
The hybrid system offers a choice of selecting between different control
strategies:
CONTROL STRATEGY: CO2 OPTIMISED
The CO2-optimised mode (factory setting) uses environmental factors
to determine when the heat pump or boiler is to be operated to achieve
the highest CO2 reduction.
The environmental factors for fossil fuel and electricity must be set. The
environmental factor (or primary energy factor, PEF) indicates the
fossil-fuel consumption incurred until the energy (electricity/gas) is
available at the corresponding heat appliance. A heat pump uses the
input energy more efficiently than a boiler. However, the electricity used
generally involves a larger amount of fossil-fuel consumption. The
following statement applies to both environmental factors: the lower the
values, the better this is for the environment.
Examples:
Electricity from a gas-fired power station that runs at 45 % efficiency has
an environmental factor of:
• 1/45 % = 1/(45/100) = 1/0,45 = 2,2.
Mix with an efficiency of 38.4% has an environmental factor by:
• 1/38,4 % = 1/(38,4/100) = 1/0,384 = 2,6.
Natural gas, which is supplied with a loss of 12% (88% efficiency), has
an environmental factor of:
• 1/88 % = 1/(88/100) = 1/0,88 = 1,1.
CONTROL STRATEGY: COST OPTIMISED
With the cost-optimised mode, the system control decides on the basis
of current energy prices. Rising gas prices result in longer operation of
the heat pump, whilst rising electricity prices result in longer operation
of the boiler.
The cost ratio is the difference between Gross electricity and gas prices
converted to Nett.
Example:
• Cost of electricity: 24 p/kwH
• Cost of Gas:8 p/kwH
Cost ratio (net):(24/8)x0.902=2.7
This is the ratio which must be inputted to the system controller.
This conversion can be made using table 47 on page 82 of this manual.
CONTROL STRATEGY: CHANGEOVER
In weather-compensated mode, the boiler delivers the entire heating
energy below a set outside temperature (dual mode changeover
threshold). The heat pump is not in operation.
At temperatures above the set outside temperature, the heat pump
delivers the entire heating energy where possible. The boiler is
operational when the heat output of the heat pump is not sufficient to
cover the heat load.
CONTROL STRATEGY: CO2 COST MIX
Mixed operation of environmental factors and cost.
The environmental factors and the energy price ratio are considered.
Information under the control strategy: CO2 optimised and control
strategy: Cost-optimised, note on page 41.
These parameters can be set either via the FW 200
weather compensated controller or via the hybrid
control module. These values are transferred and
overwritten respectively. The following section will
describe how to make the settings using the FW 200
weather-compensated controller. For information on
making settings on the hybrid control module, see
chapter 6.2.23.
The actual environmental factor for the available energy
(electricity/gas) must be checked with the energy
supplier.
The energy:price ratio for electricity and fossil fuel must
be adjusted regularly to the actual price ratios.
The appendix includes the weighting factors for different
electricity and gas prices (chapter 13.1, page 82,
table 47).