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Eberspacher Diesel Water Heater Models
Hydronic  D4WS & D5WS  Heaters.
D5WS   (24v)
Manufactured ???? onwards, current model.
Technical Installation manual       2007, 2011
Troubleshooting & repair manual  2011
Parts manual                             2011


Automatic settings            Start   High    Low    Standby.
Heat output                                  5000    2400    0  watts
Fuel consumption                         0.62     0.27    0  l/hr
Power consumption           110      37       10      8  watts
Power consumption water pump   < 15 watts
Water throughput                        850 at 0.1 bar  l/hr
Water pump, Fuel pump              External
Minimum water flow rate              250                 l/hr
Length 220,  Width 86,  Height 102      mm
Combustion air inlet pipe 20mm
Exhaust outlet pipe 24mm.
Manuals show heaters as 12v but normally are 24v.

Spare parts availability    Current model.
Servicing see Hydronic servicing page.
Wiring connection details see manuals.
Fault finding information see Faults pages.
D4WSC & D5WSC Heaters
Eberspacher current water heater models with brief details, for older models see the other pages.
Heater models with a Z in the number are OEM models and are often non standard, see OEM Models page. Our practical knowledge of water based heaters is limited so these pages will not be as comprehensive as the air models. Manufacturing date information is not published, our only information is the dates of manuals or on heater labels. Technical information given is just a quick guide, check with manual or dealer is it is critical. If heaters have a servicing page any extra information will be found there, otherwise it will be included on these pages. Some water heaters are not manufactured in both 12 and 24 volt versions. Any information on dates of your heater label is welcome as are photographs of heaters. Read our Buying advice page before buying to avoid very expensive mistakes.
1  Current Eberspacher Water Heater Models
Top:- Fuel inlet left, Water outlet, water inlet.
Bottom:- Combustion air inlet, Exhaust outlet.

D4WS  (24v)
Manufactured ???? onwards, current model.
Technical Installation manual       2011
Troubleshooting & repair manual  2011
Parts manual                             2008, 2011
Known dates on labels                2012

Automatic settings       Start    High  Low  Standby
Heat output                             4300    2400   0  watts
Fuel consumption                   0.53     0.27    0  l/hr
Power consumption     110      35      10       8  watts
Power consumption water pump   < 15 watts
Water throughput               800 ± 100 at 0.1 bar  l/hr
Water pump, Fuel pump              External
Minimum water flow rate              250                 l/hr
Length 220,  Width 86,  Height 102      mm
Combustion air inlet pipe 20mm
Exhaust outlet pipe 24mm.
Manuals show heaters as 12v but normally are 24v.

Spare parts availability    Current model.
Servicing see Hydronic servicing page.
Wiring connection details see manuals.
Fault finding information see Faults pages.

Hydronic  MII  -   M8  M10  M12  Heaters
Hydronic  LII16   LII24   LII30   LII35   Heaters
Unlike smaller Eberspacher heaters, Eberspacher LII heaters pump fuel into the burner under pressure.
These heaters should be installed and serviced professionally.
D4WSC  (12v)
Manufactured ???? onwards, current model.
Technical Installation manual       2003, 2011
Troubleshooting repair manual     2002, 2008
Parts manual                             2007, 2008
Label dates 2008, 2011 (2001/2/3 shown in repair manual)

Automatic settings     Start   High    Low    Standby
Heat output                           4300    2400    0  watts
Fuel consumption                  0.53     0.27    0   l/hr
Power consumption   120     48         23      8  watts
Water pump, fuel pump*              Internal
*Fuel pump can be re-fitted externally if pipe lengths exceeded.
Water throughput                 900 ± 100 at 0.1 bar  l/hr
Minimum water throughput           250                     l/hr
Length 220,  Width 86,  Height 160      mm
Combustion air inlet pipe 20mm
Exhaust outlet pipe 24mm.

Servicing plus more information see Hydronic servicing page.
Spare parts availability    Current model.
Wiring connection details see manuals.
Fault finding information see Faults pages.


Top center:- Bleed valve
Right top to bottom:- Water outlet, Water inlet, Fuel inlet.
Bottom:- Combustion air inlet, Exhaust outlet.
D5WSC  (12v)
Manufactured ???? onwards, current model.
Technical Installation manual       2003, 2011
Troubleshooting repair manual     2002, 2008
Parts manual                             2007, 2008
Label dates 1998


Automatic settings     Start   High    Low    Standby
Heat output                          5000    2400    0  watts
Fuel consumption                  0.62     0.27   0   l/hr
Power consumption   120     48       23      8  watts
Water pump, fuel pump*              Internal
*Fuel pump can be re-fitted externally if pipe lengths exceeded.
Water throughput                  0 ± 100 at 0.1 bar  l/hr
Minimum water throughput   250                          l/hr
Length 220,  Width 90,  Height 160      mm
Combustion air inlet pipe 20mm
Exhaust outlet pipe 24mm.

Servicing plus more information see Hydronic servicing page.
Spare parts availability    Current model.
Wiring connection details see manuals.
Fault finding information see Faults pages.
Hydronic M8 Biodiesel
Auto settings            Power  Large  Med  Small  Standby
Heat output               8000   5000   3500  1500   0  watts
Fuel consumption      0.90    0.65    0.40   0.18   0   l/hr.
Power consumption    55       46       39      35    32 watts
Power starting 200 watts
M8 is bio diesel compatible.

Hydronic M10
Auto settings             Power  Large  Med  Small  Standby
Heat output               9500   8000   3500  1500   0  watts
Fuel consumption      1.20    0.90    0.40   0.18   0   l/hr.
Power consumption    86       60       39      35    32 watts
Power starting 120 watts

Hydronic M12
Auto    Power  Large  Med1  Med2  Med3  Small  Standby
Heat out 1200  9500   8000   3500  1500   1200    0  watts
Fuel       1.50    1.20    0.65     0.40   0.18    0.10     0   l/hr.
Power    120     132      86       46      39        35      34 watts
Power starting 120 watts

All models
Manufactured ???? onwards, current models.
Technical Installation manual       2012
Troubleshooting repair manual     2009
Parts manual                             2009
Fuel pump                                 External
Water pump                               External fixed on heater
Water throughput                        1400 at 0.14 bar        l/hr
Minimum water throughput           500                          l/hr
Available in 12 or 24 volt versions.
Length 331,  Width 138,  Height 220      mm
Combustion air inlet pipe 24.5mm
Exhaust outlet pipe 29mm.
The ECU determines the model, all other parts are the same.
Spare parts availability    Current models
Wiring connection details see manuals.
Servicing see Troubleshooting manual.
Fault finding information see Faults pages.
Combustion air fan and water pump have electrically commutated motors.
Cutaway MII heater on Eberspacher stand at Southampton boat show 2012.
The manuals for the MII heater range reveal a few details of interest.
The current drawn by the M8 model is higher than the M10 and M12 to help burn off Bio diesel deposits. The M12 has a high number of heating power steps and is believed to be a later model. Combustion air fan and water pump have electrically commutated motors. That means the motors have no brushes, the armature is driven magnetically. Theoretically this should mean less motor failures so good news. The bad news is the blower motor and the ECU are a single unit, if either fail the complete unit has to be replaced.
When replacing a MI heater with an MII a conversion wiring kit is required. Both use the same connector but due to a big cockup the pin connections on the new heaters are rotated 180 degrees so for example a pin that should be top left is bottom right. No damage occurs if a new heater is plugged into an old loom, it just does not work. Ooops!!
Hydronic  II  -   D4S  D5S  D5SC  Heaters
These heaters are currently not being sold in the UK for technical reasons but are being sold in Europe.