Vaillant geoTHERM Installation Instructions Manual

Also see for geoTHERM SERIES: System Installation Instructions Installation and servicing Instructions for use Operating instructions

Contents

Description of functions and units10 Installation instructions geoTHERM 0020051574_0433.2 Functional principleThe Vaillant geoTHERM heat pump VWS uses geothermalheat as its heat source, whereas the geoTHERM heat pumpVWW uses well/groundwater.Electricauxiliaryheater Domestichot watertankHeating circuitBrine circuit/well water circuitCoolantcircuitDomestichot waterCold waterHeating/cylinderchargingdiverter valveCondenserHeat sourceBrine pump/Well pumpEvaporatorCompressorExpansionvalve2134Heatinginstallation3.2 Principle of operation of the heat pumpThe heat pump consists of separate circuits which are cou-pled with one another by means of heat exchangers. Thesecircuits are:– The brine circuit with which the thermal energy is trans-ferred from the heat source to the coolant circuit.– The coolant circuit, which releases the thermal energy tothe heating circuit by means of evaporation, compres-sion, liquefaction and expansion.– The heating circuit, which supplies the heating and DHWloading for the domestic hot water cylinder.The evaporator (1) is used to connect the coolant circuit tothe geothermal heat source, from which it extracts thermalenergy. At the same time, the physical state of the coolantchanges; it evaporates. The condenser (3) is used to con-nect the coolant circuit to the heating installation, to whichit releases the thermal energy again. In so doing, the cool-ant becomes liquid again; it condenses.As thermal energy can only pass from a body at a highertemperature to a body at a lower temperature, the coolantin the evaporator must have a lower temperature than thegeothermal heat source. On the other hand, the tempera-ture of the coolant in the condenser must be higher thanthat of the heating water in order to be able to release thethermal energy to it.These different temperatures are produced in the coolantcircuit by means of a compressor (2) and an expansionvalve (4) between the evaporator and condenser. The cool-ant flows in vapour form from the evaporator into the com-pressor, where it is compressed. This causes the pressureand temperature of the coolant vapour to rise sharply. Afterthis process, the coolant flows through the condenser,where it releases its thermal energy to the heating water bycondensation. It flows as a liquid to the expansion valve,where it expands significantly and, in so doing, loses muchof its pressure and temperature. This temperature is nowlower than that of the brine/well water flowing through theevaporator. The coolant can thus take up more thermalenergy in the evaporator, turning into vapour in the processand flowing to the compressor. The cycle starts again.If required, an external electric auxiliary heater can beswitched on by the integrated controller.To prevent condensation from forming inside the unit, thecables of the brine circuit/well water circuit and the coolantcircuit must be cold insulated. If condensation still occurs,(7) ¬ Fig. 3.5 and ¬ Fig. 3.6 are collected in a condensatepan and guided under the heat pump. Drop formation underthe heat pump is thus possible.The geoTHERM heat pump VWS can be equipped withexternal passive cooling in order to provide for comfortable,cool room temperatures in your living rooms at high out-side temperatures during the summer operation. For thispurpose, additional components are required in the heatpump hydraulics. An auxiliary cooling heat exchanger, anadditional mixer valve and an auxiliary diverter valve.In the case of Vaillant heat pumps with cooling function, theprinciple of “passive” cooling is applied, in which thermalenergy is transported via underfloor heating from therooms to the ground without compressor operation andtherefore without coolant circuit operation. The heatingwater, which when supplied is colder than the room temper-ature, absorbs thermal energy from the rooms and ispumped via the heating circuit pump into the cooling heatexchanger. The brine pump also conveys the colder brinefrom the ground into the heat exchanger of the brine cir-cuit, which is operated using the counter flow principle. Inthe process, the warmer heating return emits thermalenergy to the colder brine circuit, so that the brine which isheated to some degree is guided again to the floor. Theannealed heating flow circulates again through the circuitof the underfloor heating, where the water can reabsorbthermal energy from the surroundings. The cycle startsagain.