

*illustrative photo
KORAL
Eco-pea coal boiler with proven structure
KORAL is a modern eco-pea coal boiler with feeder, which is characterized by ease of use. The design solutions of the boiler refer to the highly rated MERKURY boilers by Zębiec. The boiler operation is controlled by a modern ELSTER controller with the possibility of controlling 4 pumps, a mixing valve, and as an additional option it features several independent heating circuits or an Internet module.
Up to 95.5% – high thermal efficiency
The PID algorithm used in the controller automatically regulates the amount of fuel fed and the blow-in power. Such control ensures more economical, more efficient and cleaner combustion.
Modern solutions
The boilers utilise a system preventing backflow of smoke into the feed hopper. It is possible to set a programme in the controller for disinfection of the domestic hot water tank. To increase the convenience of use, the boiler can be purchased with the right or left hand side feeder.
Ecological pea heating
The boilers meet stringent requirements of the Class 5 and Ecodesign in terms of clean exhaust, which means that KORAL boilers by ZĘBIEC meet the conditions for obtaining funding under the CLEAN AIR (CZYSTE POWIETRZE) programme.
Bin drying system
Certified P265GH boiler sheets
7-year warranty on the tightness of the water body (after meeting the conditions of the operating manual – return protection)
24 months warranty of efficient boiler operation
Automatic boiler operation
High thermal efficiency reaching 95.5%
Low level of harmful substances in exhaust gases
Ceramic chamber of the boiler
Mechanical fuel supply
Increased safety of use owing to application of sensors
Screw movement sensor
As an additional option
Cooperation with the weather regulator
Boiler control via the Internet
Boiler control using the room panel
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Pea coal type II 31.2 (8-20mm) |
LIDER PID DYNAMIC controller
The boiler operation is controlled by a modern LIDER PID DYNAMIC controller with the feature of controlling 4 pumps, a three- or four-way mixing valve. And several independent heating circuits, controlling via room panel and Internet, weather-based controlling etc.
Additional equipment
- ROOMSTER II RTX room controller
- ETH-100 Internet module
- RTx Lider wireless communication module
- LIDER KTY Weather sensor
- User manual – KORAL 14-25
- User manual – KORAL 10
- Controller user manual – LIDER PID DYNAMIC
- Energy label – KORAL 10
- Energy label – KORAL 14
- Energy label – KORAL 18
- Energy label – KORAL 22
- Energy label – KORAL 25
- KORAL 10 – product card
- KORAL 14 18 22 25 – product card
- EC Declaration of Conformity No. 65/2019
- Certificate – KORAL 10
- Certificate – KORAL 14
- Certificate – KORAL 18
- Certificate – KORAL 22
- Certificate – KORAL 25
- Attestation – KORAL 10
- Attestation – KORAL 14
- Attestation – KORAL 18
- Attestation – KORAL 22
- Attestation – KORAL 25
BOILER | Height [mm] | Width [mm] | Depth [mm] | A [mm] | B [mm] | C [mm] | D [mm] | E [mm] | F [mm] | G [mm] |
KORAL 10 | 1222 | 1040 | 728 | 156 | 972 | 1050 | 159 | 430 | 743 | – |
KORAL 14 | 1342 | 1190 | 888 | 156 | 1095 | 1174 | 159 | 516 | 883 | 1258 |
KORAL 18 | 1412 | 1190 | 888 | 156 | 1165 | 1244 | 159 | 516 | 883 | 1328 |
KORAL 22 | 1487 | 1190 | 888 | 156 | 1239 | 1324 | 159 | 516 | 883 | 1402 |
KORAL 25 | 1557 | 1190 | 888 | 156 | 1309 | 1394 | 159 | 516 | 883 | 1472 |
Identification | J.m. | KORAL 10 | KORAL 14 | KORAL 18 | KORAL 22 | KORAL 25 |
Energy efficiency class | B | B | B | B | B | |
Rated thermal power | kW | 10 | 14 | 18 | 22 | 25 |
Energy efficiency ratio | 86 | 85 | 85 | 86 | 85 | |
Scope of work | kW | 3,0-10 | 4,2-14 | 5,4-18 | 6,6-22 | 7,5-25 |
Thermal efficiency | % | up to 95,5 | up to 94,6 | up to 92,8 | up to 94,0 | up to 94,1 |
Feed hopper capacity* | dm3/kg | 120/95 | 166/133 | 188/150 | 211/169 | 233/186 |
Boiler water capacity | dm3 | 42 | 80 | 83 | 93 | 99 |
Min. required natural draught | Pa | 20 | 20 | 20 | 25 | 25 |
Min. height of the chimney | m | 5 | 5 | 5 | 7,5 | 7,5 |
Min. cross section of the chimney | cm x cm Φ cm | 20 x 14 Φ 18 | 20 x 14 Φ 18 | 20 x 14 Φ 18 | 20 x 14 Φ 18 | 20 x 14 Φ 18 |
Flue diameter | mm | Φ 159 | Φ 159 | Φ 159 | Φ 159 | Φ 159 |
Water pipes outlet/return (internal threaded) | mm | G 1 1/2″ internal | G 1 1/2″ internal | G 1 1/2″ internal | G 1 1/2″ internal | G 1 1/2″ internal |
Max. working pressure | bar | 1,5 | 1,5 | 1,5 | 1,5 | 1,5 |
Boiler weight without water | kg | 270 | 450 | 470 | 510 | 525 |
Boiler class according to 303-5:2018 | 5 | 5 | 5 | 5 | 5 | |
Ecodesign | yes | yes | yes | yes | yes |
* For reference only; depends on bulk density, calorific value, fuel grade, etc.
Boilers „Zębiec” | Thermal power | Room area [m2] depending on the building’s penetration coefficient (insulation) | |||
U > 1 [W/m2K] | U ~ 0,7 [W/m2K] | U ~ 0,5 [W/m2K] | U ~ 0,3 [W/m2K] | ||
without insulation | ~5 cm styrofoam | ~8 cm styrofoam | ~10 cm styrofoam | ||
KORAL 10 | 10 | 86 | 100 | 120 | 155 |
KORAL 14 | 14 | 120 | 140 | 165 | 215 |
KORAL 18 | 18 | 155 | 180 | 210 | 275 |
KORAL 22 | 22 | 195 | 220 | 260 | 340 |
KORAL 25 | 25 | 215 | 250 | 295 | 385 |