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Old 12-29-2013, 04:03 PM   #1
Aqua Puttana
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Default Some 2004 Espar Heater Notes

This is not really a Write-up, but not just a question either so I'll include it in Database for any information it provides. There are many other references and tips found in the Database section too.

See also The Espar Files
bc339 Bruce did a great job compiling information.

Espar parts which are verified correct for my 2004 Booster Heater:
(Kubbie's 2006 is the same as my 2004.)
Burner with integral fuel pipe = Burner 25 1922 10 00 00 (no fuel strainer needed)
Gasket and Seal 20 1752 99 01 01 Newer Number = 20.1820.99.0001.0A (All D5 units)
Glow Plug (with integral leads) 25 2106 01 10 00 aka 25.2106.01.1000 aka 25.2106.01.1000.2F
Blower Assembly 12V/D5W SC 25 1922 99 16 00
Exhaust Tube = 24mm inside diameter. Approx 10" L. needed to muffler

Originally Posted by Type2Teach View Post
After trying to order parts from online and having Paul call me, I would suggest that anyone ordering from them for the first time should call and order over the phone. Saves alot of confusion.

The Varnish Sniffers across the pond have been busy revealing interesting information about the Espar heaters since I last visited their site.
Thanks goes to Seans for the update.

Originally Posted by seans View Post
Hi Vic!

The British site which is a growing fountain of Espar information has more photos of a teardown and cutaways: - "home page" - cutaway photos of a different model burner - shows cutout of burner showing screen deep inside.

Seans also has some great info for repairing the blower motor.

Per Espar Literature
"The Hydronic D5 generates 17,500 BTU of heat for quickly pre- heating your trucks"

"The heaters regulate the coolant temperature between a low of 149F (65C) and a high
of 167F (75C) by automatically cycling the heater between the heat levels to maintain
high heat temperature."
The Sprinter Espar seems to control to a bit higher temperature range.

Note: One expert I've communicated with warned that Bio-fuel is a problem with the Espar heaters. He even cautions against 5% and suggests installing a "Day Tank" and running the heaters on Kerosene. I can't disagree, but installing a day tank with easy fill capability is likely easier said than done. He mentioned that a coffee colored residue which is harder to clean than the normal black soot is one evidence of bio-fuel rlated problems.
Added: I was recently made aware that the NAS aka NAFTA T1N models have the fuel fill body metal chamber on the passenger side. That area may provide a place to add a fill port to an Espar day tank mounted under the Sprinter.

Some knowledgeable Espar folks.
Ray - Espar of Michigan aka

Guy - Boat Electric - Seattle, WA

Be aware that there is some misleading information found in some Espar Sprinter specifc PDF manuals. (See post #5 below.)

My 2004 Booster Heater label information is as follows.


25 2343
00 0023
43W 12 volt
5.0 KW
Max 2.5 bar
ZGS 001

3/4" coolant hose in and out. (Inlet is on outside corner.)
The Espar D5W
Minimum water flow through the heater = 250 l/h. (Approx. 1 gpm)

Booster vs Aux Note.
My Aux style 2006 Espar is a Espar D5WS which has 2 each electrical connectors. The same main connector as my 2004 D5WZ Booster with a 2nd smaller connector on a pigtail.

My Espar doesn't have a glow plug strainer and seals at all. It has a integral fuel pipe built into the burner assembly. The glow plug fits into a "D" shaped chamber which has a screened "window" out into an "intermediate" burner chamber. (Don't dig the screen out if you clean the glow plug chamber. In fact, don't use any digging tools near the screen especially above it where the fuel weeps in.)

Espar2004Sprinter D5Burner.jpg



Integral Pipe Burner Style notes.

There is a similar looking D5 burner with no integral fuel pipe that will not work. The no fuel pipe burner part number 25.2216.10.0000 aka 25 2149 10 00 02 won't work if the integral fuel pipe no fuel strainer burner is what you have, so don't be fooled.

Burner with integral fuel pipe - no fuel strainer = Burner 25 1922 10 00 00 (fits model 25 2009 05 and 25 2031 05 among others.)

The gasket and seal kit appears standard for D5 units.
Gasket and Seal
#9 Seal 20 1752 99 01 01
Newer Number = 20.1820.99.0001.0A

Note that some D5 Espar heaters have a fuel strainer in an external style glow plug holder. The fuel pipe is integral to that glow plug holder. Mine has the burner tube with integral fuel pipe.

Early "S" Heaters

4a = Burner 25 1922 10 00 00 fits model 25 2009 05 and 25 2031 05 among others. (My 2004 with built in fuel pipe.) (Use the Espar model number if they don't like the Sprinter OEM model information.)

11a = Glow Plug 25 2106 01 10 00 aka 25.2106.01.1000 with integral leads. (My 2004.)

4 = Burner h5 2219 Part # 25.2216.10.0000 Part stamped 25 2149 10 00 02
(Fuel Strainer type burner. No integral fuel pipe.)


This youtube shows a unit with the integral fuel pipe. The unit shown has the lug type glow plug, not the glow plug with integral leads as mine has. My Espar has Torx fasteners.

This youtube shows the newer style fuel strainer in an Airtronic.
I've removed and taken apart my heater quite a few times now. I cleaned different things as I progressed. I finally got it to operate for a few times, but it won't start first time reliably. Once it fires it runs until the engine is up to temperature.

The heater burner chamber was so clean from the beginning, the air section like new, and the muffler/pipe is pristine, so I don't think this unit has ever operated since new.

Some things that I've learned.

The fuel doesn't squirt in under pressure. It more flows in like a traditional kerosene pot burner stove with a carburetor. In my old style unit the metal screen enters through a slot to provide a "wick" which lets fuel seep in from the fuel pipe deeper down in the glow plug chamber. Until cleaning those weep holes with a dental pick and shoving a thin wire right down the fuel pipe I didn't get the heater to actually fire, it just produced white smoke. When I stuck the wire down the fuel pipe it did seem to hit some resistance at first so that pipe may have been restricted.

What I learned after it fired.
The earlier times that I thought it was firing it was just burning fuel in the glow plug chamber which produced white smoke and did not ignite the main chamber. Actually evaporating might be a better term than "burning".

The faulty operation sequence as I recall it.
The engine noise at idle makes it hard to be certain of some noises. After starting the engine the Espar combustion fan would cycle for a quick ramp up. After a short fan run cycle to purge the combustion chamber the fuel would pulse in. The heater would begin pouring out white smoke. I thought that meant it was firing because the combustion fan would ramp up. After ramp up I'd see even more white smoke. Then the fuel pump would stop, the fan would ramp down, raw diesel fuel would drip out the exhaust (I later learned that my muffler packing was soaked with fuel.), the fan would run a while (combustion chamber purge) and then slow down. After (if?) the first start fails, the blower runs on a low speed into a 2nd start attempt. If the 2nd start fails, the blower continues to run through a standard cooldown cycle and then locks out for no more attempts until a power down reset.

Each failed ignition attempt dumps about 1 1/2 teaspoons of unburned (raw) diesel into the combustion chamber. No ignition at all = x2 start attempts = approx. 3 teaspoons of fuel. The combustion fan carries that fuel to the exhaust system. Once the muffler stuffing is saturated the fuel will spill out from the exhaust system.

I learned that when the heater actually fires off there was just a little white smoke and then the Espar would begin to roar. You will recognize the roar as opposed to just the fan ramping up. It sounds like a low rubble not just a whine. The whine is just the fan turning up to very high speed. For each start attempt the fan will run and the fuel pumps until the flame sensor (actually temperature) sensor kicks into the circuit and realizes that there is no main flame (no temperature rise). It then stops the fuel and the fan ramps back down, but not shut the fan down right away. As I said, the white smoke I saw is just the glow plug chamber fuel burning (evaporating?) and not actually igniting the main burner.

Firing correctly = A little white smoke then No Smoke. Not enough air = Black smoke. Unburned fuel = White smoke.

I plan to open the heater again and try to clean the glow plug chamber holes a bit better. I think that may help to get more reliable starts. Anyone have any input or experience for this?

Edit: I did open up the holes more. That made my heater not fire at all. It just made it a wonderful smoke machine.

The screen in the "D" shaped glow plug chamber is critical to the main burner ignition. I have dug out and uncovered a slot just above the screened 3/16" hole window. My observation is that the screen covers the little 3/16" window hole (the screen needs to only surround it), but it also continues up into the main fuel chamber. The screen then acts like a kerosene lamp wick in that the segmented fuel is ignited by the glow plug and the flame travels to the main burner.

The screen does act like a kerosene lantern wick. The "window screen" goes up into the fuel pipe chamber. A regulated fairly tiny amount of fuel weeps down onto the screen where it is "segmented" to be ignited by the glow plug. Once it has ignited, the flame goes out into an inner chamber which is between the center round (combustion air) hole and the "D" shaped glow plug hole. That flame path via the intermediate chamber is what ignites the main burner.

When I probed at my screen "weep holes" (which are actually a slot for the screen) I opened them up too much. With too much fuel leaking into the chamber I think that it is over-whelming my glow plug. It then just creates white smoke and doesn't ignite.

I tried different things to repair the screen and slot with no success. (Success ultimately!!! See post #3.) I have decided to order a new burner and see if that fixes my problems. (about $260) I believe it will. At one point I must have hit close to the correct fuel drip combination with my added screen before I opened the "slot weep holes" too much. The heater was firing off about every other start sequence. Once it fired it ran perfectly. I decided to improve that starting ratio and really messed up the burner. For engine pre-warming use I should have just been happy to monitor that the heater fired up properly.

Some additional glow plug chamber info is here in another thread which I started.

Espar D5 "S" Heater Glow Plug

Espar D5 Fuel Quantity Test

Fuel Quantity Test
The fuel Quantity should be tested if the heater has difficulty
starting or maintaining a flame.

Note: Measure the fuel quantity when the battery is
sufficiently charged. At least 11V and at
most 13V should be applied at the control
unit during measurement.

• Remove metering pump cover in the cases of SC versions.
• Pull the fuel line off the combustion chamber and insert
into a graduated measuring glass
• Switch the heater on, when fuel delivery is uniform
(approximately 40 seconds after switching on), the fuel
line is full and bled.
• Switch heater off
• Empty measuring glass and replace

• Switch heater on
• Fuel delivery stars automatically approximately 40
seconds after switching on
• Hold the graduated measuring glass at the glow pin
height during measurement
• After 90 seconds of fuel delivery, it will shut off
• Switch heater off.
• Read off quantity of fuel delivery in the graduated
measuring glass


Nominal value


Hydronic D5W SC

8.6 cm3 / 90 seconds - Maximum Qty
7.5 cm3 / 90 seconds - Minimum Qty

7.5 ML = approx. 1 1/2 teaspoons

I found that an old Baby Medicine Dosing Spoon worked perfectly to measure the fuel output. The output from my pump was at the 7.5 ML low end of the specification. (Note that the 90 second test includes a combination of low pulse and high pulse pump operation. Low pulse = ignition cycle. High pulse = ramp up until no flame sensor cutoff.)


The fuel doesn't "pump" out it more trickles out. You can feel the fuel line pulse as the fuel is "pumped".


Some other 2004 Espar Booster Heater threads which I've posted are here:

Remove Espar Heater from T1N

General Espar Heater Wiring Information

Cabin Fan Resistor Circuits

T1N Booster Heater Wireless Control

Some Misc Information

Espar D5 Heater
5 kW (17,000 BTU/hr) - High
2.4 kW (8,200 BTU/hr) - Low

Approx. 12V Power Consumption

4.16 amps High
1.91 amps Low

Approx. Fuel Consumption (+/- 10%)

0.62 l/hr (0.16 US gal/hr) High
0.27 l/hr (0.08 US gal/hr) Low

0.62L = approx. 2.620587 cups

As an aside.
Using 5KW as the +/- heat rating.
It would take approx. 40 amps at 120 volts or 400 amps at 12 volts to produce that amount of heat. I believe that helps to illustrate why diesel heaters are used in vehicles and not electric heaters.
DAD NAS (N. Amer. Spec) 2004 140 2500 >330,000+ mi. Arctic Whitewash Brush-tone Grey
2006 Freightliner 140 2500HC >183,000+ mi. Arctic Whitewash (Spotted Snow Leopard accents)
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Last edited by Aqua Puttana; 12-04-2018 at 12:54 PM.
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