The flue gas temperature is the importantpoint – Operational descriptionSecurity flowBoiler body with heatrecovery surfacesSelf-optimizing controlHeating flowFour-way mixer with servomotorHeating returnFan burnerBoiler circuit pumpFlue gas passes,washed by the boiler waterConnection for expansionvessel and KFE cockRefeed ofthe residual heat~ 50 – 60 °CFlue gas fanCondensate drainHeat exchanger for recoveryof the residual heatNeutralization boxwith natural granulate(no disposal required)Comparison of the flue gas losses Comparison of the energy saving Comparison of the flue gas temperatures14 %12 %10 %8 %6 %4 %2 %0 %35 %30 %25 %20 %15 %10 %5 %0 %200°C175°C150°C125°C100°C75°C50°C25°C0°Cn Old boiler, 15 – 20 yearsn Modern low-temperature boiler■ Partially condensing boiler■ <strong>Kroll</strong> BKAll indications without engagement!
Heating technoloy for genereations –a perfect heating systemThe <strong>Kroll</strong> condensing boileroperates permanently,without any restrictions,in a condensing mode allyear round.n According to the condensingtable for heating gases,vapour in waste gases of oil willcondense below approximate47°C, and in waste gases ofnatural gas the dew point isunder approximate 57°C,relating to the water/CO 2content in the respective fuel.n As at the <strong>Kroll</strong> condensingboiler the flue gas temperatureis, due to the cooling of theexhaust gases by thecombustion fresh air, alwaysunder 47/57°C, a permanentcondensation is obtainedindependently from the returntemperature of your system.nThe burner is perfectlyintegrated into the nice-lookingfront cover, which gives anadditional insulation andreduces operation noises.n The combustion gases are ledthrough two heat exchangersafter they have passed thecombustion chamber.This leads to maximum energyutilisation.n The first heat exchanger isflowed by the water of the firstheating circuit (boiler) andcools the waste gas down toabout 70°C. The second, highlyefficient tube heat exchangermade of a special plastic,is precision-manufacturedand takes most of the energycontained in the exhaust gasesby cooling them down underthe relevant dew point.This condensing procedureis followed by an additionalenergy exploitation.The recovered energy is fedto the burner as pre-heatedcombustion air.nThis is why the degree ofcondensation does notdepend on the returntemperature, but predominantlyon the outside temperature.That means, that the <strong>Kroll</strong>condensing boiler reachesits highest efficiency at thattime, when highest efficiencyis needed – in winter time –and heat is required most,under full load requirements.nBy the constantly high creationof condensate, a large part ofsulphur content, contained inthe fuel, is washed out andneutralised. This “de-sulphurisation”contributes to theprotection of our environmentand also helps to reduce thecreation of acid rain.nUp to eight <strong>Kroll</strong> condensingboilers can be run in acascade via a master control.So you can run up to 2000kW around the year underpermanent condensationwith a maximum flue gastemperature of 47 °C.Further characteristics:nSecondary heat exchangerfor heat recovery made ofspecial plastic materialn Neutralisation boxn Solar controllern The standard controller cancontrol 2 heating circuits,domestic hot water and thecirculation pump.More heating circuits can becontrolled with the additionof extra control items.n Boiler circulation pumpnHigh-quality boiler insulation n Boiler casing easy to installScope of deliveryBK20/BK30– Permanently condensing boiler,including burner (oil or gas)– Cable kit for 2-stage burner– Neutralization box, including 3 kggranulate– Control, includingExternal temperature sensorFlow sensor for heating circuit 1 (4 m)DHW sensor (4 m)Plug for pump heating circuit 1Plug for mixer heating circuit 1Plug for DHW pumpPlug for circulation pumpPlug for feeding pumpPlug for solar pumpIntegrated solar control mode(temperature difference)– Boiler connection piece for flue gaspipe LAS DN80/125(LAS = air/flue gas system)– Flue gas passes brush– Boiler body brush– 4 pieces HT elbow pieces 87°/Ø 40 mmBK50 – BK100– Permanently condensing boiler,including burner (oil or gas)– Cable kit for 2-stage burner– Neutralization box, including 3 kggranulate– Control, includingExternal temperature sensorFlow sensor for heating circuit 1 (4 m)DHW sensor (4 m)Secondary flow sensor (4 m)Plug for pump heating circuit 1Plug for mixer heating circuit 1Plug for DHW pumpPlug for circulation pumpPlug for feeding pump– Flue gas fan– Brush (flue gas passes + boiler body)– 4 pieces HT elbow pieces 87°/Ø 40 mmBK250– Permanently condensing boiler,including burner (oil or gas)– Cable kit for 2-stage burner– Neutralization box, including 9 kggranulate– Control, includingExternal temperature sensorFlow sensor for heating circuit 1 (4 m)DHW sensor (4 m)Secondary flow sensor (4 m)Plug for pump heating circuit 1Plug for mixer heating circuit 1Plug for DHW pumpPlug for circulation pumpPlug for feeding pump– Flue gas fan– Brush (flue gas passes + boiler body)– 4 pieces HT elbow pieces 87°/Ø 70 mm
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