I think I found a heater booster, but no switch

brutimus

Member
From your datacard you just have the "booster" arrangement.

So: it will only operate when the engine is running
The bow-tie switch is (supposed to be) "it".
Since it requires the engine (with its belt-driven water pump) to be running for operation, i really don't know if it entails or requires a separate electric circulation pump. (the REST function does)

Here's the owner's manual's single page on it:

View attachment 73043

--dick
Thank you, sir.

I've looked through some of the schematics in hopes I'll build up the confidence to try and hot wire this thing back into action. However, said schematics are a bit scary so far.

Maybe I'll hear back from the PO if he knows anything about my conundrum.
 

david_42

New member
The heat booster and aux heater are one in the same; the difference is if you have the aux option, you can turn the heater on at any time; it's just a matter of the controls. People have retrofitted manual controls for the heater; but remember, it heats the coolant, not the cab. If you aren't getting enough heat in the cab, you might have a clogged heat exchanger.
 

Speed Racer

2006 2500HC Passenger Van
The heat booster and aux heater are one in the same; the difference is if you have the aux option, you can turn the heater on at any time; it's just a matter of the controls. People have retrofitted manual controls for the heater; but remember, it heats the coolant, not the cab. If you aren't getting enough heat in the cab, you might have a clogged heat exchanger.
While I can certainly be mistaken, I humbly disagree with the heat booster and aux heater being one and the same. Based on what I'm seeing in the manual, the heater booster is run off engine coolant; the auxiliary heater is a diesel-fired device. From the service manual for an '06, the heater booster operations are:

OPERATION
Outside air enters the vehicle through the hood opening at the base of the windshield, and passes through the ventilation housing located in the engine compartment into the heater housing located behind the instrument panel. Air flow velocity is adjusted with the blower motor speed selector thumbwheel on the A/C-heater control. The air intake openings must be kept free of snow, ice, leaves, and other obstructions for the HVAC system to receive a sufficient volume of outside air.
The automatic temperature control (ATC) system controls interior temperature by taking actual values from the temperature sensors and the CAN bus and comparing them to the nominal value of the temperature control switch. The electric pulsed heater valve is then energized depending on the requested quantity of heat and an electrically-operated water pump gives a nearly constant water flow for exact temperature regulation. If the solenoid is not energized, the coolant circuit to the heat exchanger is fully open. To control the temperature the solenoid valve is pulsed by the ATC in periods of four seconds. The mode control knob on the A/C-heater control is used to direct the conditioned air flow to the selected air outlets. The mode control knob operates the mode doors by cables connected to the mode doors.

I am no expert, and I could be totally wrong. But, that's what I'm reading, and that's my story, to which I shall stick until further notice. Just trying to help. If I'm in the way, please disregard.

Bill
 

brutimus

Member
While I can certainly be mistaken, I humbly disagree with the heat booster and aux heater being one and the same. Based on what I'm seeing in the manual, the heater booster is run off engine coolant; the auxiliary heater is a diesel-fired device. From the service manual for an '06, the heater booster operations are:

OPERATION
Outside air enters the vehicle through the hood opening at the base of the windshield, and passes through the ventilation housing located in the engine compartment into the heater housing located behind the instrument panel. Air flow velocity is adjusted with the blower motor speed selector thumbwheel on the A/C-heater control. The air intake openings must be kept free of snow, ice, leaves, and other obstructions for the HVAC system to receive a sufficient volume of outside air.
The automatic temperature control (ATC) system controls interior temperature by taking actual values from the temperature sensors and the CAN bus and comparing them to the nominal value of the temperature control switch. The electric pulsed heater valve is then energized depending on the requested quantity of heat and an electrically-operated water pump gives a nearly constant water flow for exact temperature regulation. If the solenoid is not energized, the coolant circuit to the heat exchanger is fully open. To control the temperature the solenoid valve is pulsed by the ATC in periods of four seconds. The mode control knob on the A/C-heater control is used to direct the conditioned air flow to the selected air outlets. The mode control knob operates the mode doors by cables connected to the mode doors.

I am no expert, and I could be totally wrong. But, that's what I'm reading, and that's my story, to which I shall stick until further notice. Just trying to help. If I'm in the way, please disregard.

Bill
What you're reading there sounds to me like the operation of the standard heater. The "heater booster" (and presumably the aux heater) is a diesel powered device. See my photo from a couple posts up, the service manual has a diagram of the espar unit under the headlight and labels it as a heater booster. The REST function is, as you describe, "run off engine coolant". It is simple a way to use up the leftover engine heat to warm the cab after you shut the van off. It doesn't actually generate any heat itself.

The thing I'm not 100% on (and I don't think it applies to me anyways) is whether the booster and the aux are both powered by the same espar device under the headlight. david_42 implies that they are, so I'm good with that description.
 

vanski

The most interesting member in the world
someone switched out the entire ATC console. get one of those and then you can see if your heater booster works which I hate to say that it probably doesn't. If it does, then you can down the engine off upgrade which truly is the best upgrade I've done on this forum.

Regarding my pessimistic comment re the heater; I showed a fellow sprinter-head my engine off upgrade and as a cold weather camper of course he had to make it happen. His didn't work, we found three separate heater boosters each of which had ECU problems, found a guy on this forum who claims to have everything, he sent us a non-working heater and eventually, after a month, he sent us one that had a good ecu but the blower motor was bad. We were able to frankenstein the working ecu with a working blower motor, flame sensor, and glow pin.. After 2 months we were finally able to do the upgrade...

Perhaps (hopefully!!!!!!!!) you will have better luck.
 

brutimus

Member
someone switched out the entire ATC console. get one of those and then you can see if your heater booster works which I hate to say that it probably doesn't. If it does, then you can down the engine off upgrade which truly is the best upgrade I've done on this forum.

Regarding my pessimistic comment re the heater; I showed a fellow sprinter-head my engine off upgrade and as a cold weather camper of course he had to make it happen. His didn't work, we found three separate heater boosters each of which had ECU problems, found a guy on this forum who claims to have everything, he sent us a non-working heater and eventually, after a month, he sent us one that had a good ecu but the blower motor was bad. We were able to frankenstein the working ecu with a working blower motor, flame sensor, and glow pin.. After 2 months we were finally able to do the upgrade...

Perhaps (hopefully!!!!!!!!) you will have better luck.
What a mess! I think once I dig into mine I will just do as Aqua suggested and hotwire a 12V supply over to see if my espar will rattle to life. If it does, then it may be time to do the mod. On the other hand, it's about to be back in the 60s here, so winter might be over. Maybe next year. =P
 

vanski

The most interesting member in the world
What you're reading there sounds to me like the operation of the standard heater. The "heater booster" (and presumably the aux heater) is a diesel powered device. See my photo from a couple posts up, the service manual has a diagram of the espar unit under the headlight and labels it as a heater booster. The REST function is, as you describe, "run off engine coolant". It is simple a way to use up the leftover engine heat to warm the cab after you shut the van off. It doesn't actually generate any heat itself.

The thing I'm not 100% on (and I don't think it applies to me anyways) is whether the booster and the aux are both powered by the same espar device under the headlight. david_42 implies that they are, so I'm good with that description.
The auxiliary heater option was equipped with the same H5dwz heater, but it was also configured with a 7 day timer and different harness which sends 12v to the water pump. All this is possible with the heater booster option but the heater booster is configured to only work with the engine off. Snip the t15 wire, t30, and D+ dynamo, route them through spdt relays with a switch to activate along with relays for the ATC (fan controls) and the water pump, and you have an engine off heater...
 

Speed Racer

2006 2500HC Passenger Van
Still trying to figure this out, I might have passed on some of my confusion. The diesel-fired auxiliary heater warms coolant; i.e., water. So, it may be a matter of semantics which is confusing me. The auxiliary heater has both diesel and coolant components. I still believe, nonetheless, it is different than the heater booster, which I cannot see has anything to do with the little muffler or diesel heater (other than the heat of the engine, itself, should that be diesel).

Clear as mud, I say.

Bill
 

cahaak

New member
I would recommend that you simply wire the heater booster to run from a switch and follow the thread for that noting the correct wiring diagram is not the one posted up front, but the corrected on later. Your "switch" can either be the 7 day timer or an actual switch. In any case, with this mod, you can run the booster any time you would like, engine on or off. Although the wiring diagram appears daunting, look at a short primer on relays on the web and you will actually see that it is quite easy. I see that you are in LV, but this mod is the cat's meow for those of us that live in cold climates.

In any case, if you choose to go down this route, make sure that you read through the complete thread first before you tackle anything.

Chris

PS - the two heaters are one in the same.
 

surlyoldbill

Active member
I thought they were one and the same, just different names. ESPAR, heater booster, auxiliary heater. The REST feature I believe is independent and does not need the ESPAR; it just turns on the elec coolant pump to circulate hot coolant for 30 minutes after engine is turned off (and switches vent fan to "1").
 

brutimus

Member
I would recommend that you simply wire the heater booster to run from a switch and follow the thread for that noting the correct wiring diagram is not the one posted up front, but the corrected on later. Your "switch" can either be the 7 day timer or an actual switch. In any case, with this mod, you can run the booster any time you would like, engine on or off. Although the wiring diagram appears daunting, look at a short primer on relays on the web and you will actually see that it is quite easy. I see that you are in LV, but this mod is the cat's meow for those of us that live in cold climates.

In any case, if you choose to go down this route, make sure that you read through the complete thread first before you tackle anything.

Chris

PS - the two heaters are one in the same.
I've done my fair share of circuitry, soldering, etc. And the more I read about the mod, the clearer it becomes. The first one I read was Aqua's where he wires it into the REST function. But I've since found the other, simpler method of just wiring it into an on/off switch. That's what I'll likely do if my espar turns out to be operational.
 

Aqua Puttana

Poly - Thread Finder
Ho boy...

THE OEM T1N SPRINTER ESPAR DIESEL HEATERS ARE ALL THE SAME. They heat the engine coolant which is circulated through the cabin heater core and the engine.

There are some variations on burner type with the fuel introduction (no strainer, strainer type burner), but the basic heaters are the same.

Booster Heater, Aux Heater.

That difference is completely dependent upon the Mercedes Benz Sprinter bastardized controls.

The Booster Heater MB designed Sprinter control only lets the Espar heater (all the same type diesel heater) operate when the engine is running and the engine temperature is below about 167F. The Booster Heater controls are not designed to operate the aux electric coolant pump.

The aux heater control is more sophisticated. It lets the operator run the heater (all the same type diesel heater) whether the engine is running or not. The control box is mounted near the shifter lever. The aux heater integrated control circuit allows the heater to run with the engine running or off. The aux heater control will operate the aux electric coolant pump when the engine isn't running.

Be careful with a simple on-off switch to enable the Espar heater. Using the REST timing circuit keeps the Espar heater from being forgotten and running for extended periods of time. None of the DIY enable circuits will know whether the fuel tank is getting extremely low on fuel until the dip tube is no longer immersed in fuel. That comment also applies to my design.

If the heater fires up and runs I see no real problem with it sitting dormant for years. That said, insects may have built a home in the intake or exhaust. That will definitely affect operation.

vic

P.S. - Going mostly by the comments in boating forums, the Espar burner control module is generally very reliable. The Espar heaters generally get more run time on boats than they ever will in a typical Sprinter.
 
Last edited:

Speed Racer

2006 2500HC Passenger Van
In hopes this might help clarify things (although, admittedly it may not), please consider the attached (hopefully) image from the parts manual on Auxiliary Warm Water Heater: Item #10 is called "Supplemental Diesel Fuel Heater", and Item #17 is called "Exhaust Muffler", as is Item #32! Thing has two tiny mufflers.

All in all, all I can contribute is superficial stuff gleaned from looking at various manuals. I've no skill or knowledge of modding this device, whatever that may be, and totally defer to those other contributors who, obviously, know a bunch more about this than I.

I shall take a seat now and observe. Best of luck. Do let us know how it works out.

Bill
 

Attachments

autostaretx

Erratic Member
Still trying to figure this out, I might have passed on some of my confusion. The diesel-fired auxiliary heater warms coolant; i.e., water. So, it may be a matter of semantics which is confusing me. The auxiliary heater has both diesel and coolant components. I still believe, nonetheless, it is different than the heater booster, which I cannot see has anything to do with the little muffler or diesel heater (other than the heat of the engine, itself, should that be diesel).
As Vic wrote: the actual fuel-burning furnace (that thing under the battery that exhausts through the wallet-sized muffler in the left front wheel well) IS the Espar.

Whether Mercedes calls *yours* "booster" or "auxiliary", it's the same (roaring, smoking) thing.
With the same silly/cute muffler.
The only differences are the control buttons and gadgets given to you (and whether it will run with the engine off).

If you had neither option (booster nor auxiliary), then there would be no furnace down there.
You would still have "standard" cabin heat, where the engine's "waste heat" coolant is routed through the "heater core" that's located (more or less) behind the radio.

Clear as mud, I say.
I think you're over-thinking a manual that went through a German to English translation exercise.
(an exercise i all too frequently engage in myself) :cheers:
((the "over-thinking" exercise, not the translations... that's Google's job :thumbup:))

--dick
p.s. the reason there appear to be two heaters in the parts page is that item (10) is the whole thing as a single part number.
The exploded "second" heater is to allow ordering individual bits.
p.p.s. there's only one muffler. They may show two different ones in the catalog for reasons of optional placements, but i've only ever seen the wheelwell version
EsparMuffLocation.jpg
EsparMuffCloseup.jpg
(hmmm... i think i'll steal brutimus' photo...)
 
Last edited:

vanski

The most interesting member in the world
same thing other than the auxiliary heater has two harnesses; the primary harness and the harness to send a signal to the water pump. the above image from Speed Racer is of the auxilrary heater compared to booster because it has two harnesses (plus it says auxiliary on the top). The wiring schematic must also be a little different as I doubt the auxiliary has a t15 wire since it can start with the engine off.

i'm starting to figure out I have way too much knowledge about these stupid little things. if i would have sank all the time I've put into my espar into my business I could buy a new 4x4 sprinter.
 

autostaretx

Erratic Member
Oh, let's confuse things a little further.
There's the "booster" option with just the bow-tie and requiring engine running.

There are two (and a half) flavors of Auxiliary control.
One *without* a 7-day timer, and one *with* a seven day timer.
In other words, you either use/have the left column of the following page *or* the right column.

AuxHeatSwitches.jpg

(note: that knob (10) does NOT exist on my 7-day timer, as the manual page kind'a hints (?transformer?))
((do not confuse the left-column switch with the rear window heater switch. That has a rectangle around the bacon))

The extra "half" flavor of the Auxiliary option is the addition of a second "heater core" under the floor behind the driver's seat to heat the passenger/cargo area. If you have *that* option you will have a switch like this:

CargoHeatSwitch.jpg
probably just to the right of your steering wheel.
And a plastic heater duct along your driver's side cargo area floor, against the wall.
It's not a second furnace, it's merely additional hot water plumbing and a fanned radiator back there.
(does NOT work with engine off)

--dick
 
Last edited:

Aqua Puttana

Poly - Thread Finder
...
probably just to the right of your steering wheel.
And a plastic heater duct along your driver's side cargo area floor, against the wall.
It's not a second furnace, it's merely additional hot water plumbing and a [finned/fanned] radiator back there.

--dick
AND, at least on my 2006, the Rear Heat fan will not work without the engine running.

I don't believe that the MB bastardized controls do anything with the Espar heater as to a relationship with the temperature setting on the ATC. If the engine coolant temperature is below 167F (some claim 180F), when enabled, the Espar will run. The ATC temperature setting may control the cabin heat as to temperature, but I'm 99% certain that the ATC doesn't affect the Espar enable as to cabin temperature.

vic

P.S. - I'm certain to break that plastic heater duct in my 2006. :bash:
 
Last edited:

autostaretx

Erratic Member
AND, at least on my 2006, the Rear Heat fan will not work without the engine running.
Thanks... i added that to my post.

P.S. - I'm certain to break that plastic heater duct in my 2006. :bash:
... i removed my plastic duct, and made plywood covers for the holes in the floor.

--dick
 

Speed Racer

2006 2500HC Passenger Van
Oh, let's confuse things a little further.
There's the "booster" option with just the bow-tie and requiring engine running.

There are two (and a half) flavors of Auxiliary control.
One *without* a 7-day timer, and one *with* a seven day timer.
In other words, you either use/have the left column of the following page *or* the right column.

View attachment 73067

(note: that knob (10) does NOT exist on my 7-day timer, as the manual page kind'a hints (?transformer?))
((do not confuse the left-column switch with the rear window heater switch. That has a rectangle around the bacon))

The extra "half" flavor of the Auxiliary option is the addition of a second "heater core" under the floor behind the driver's seat to heat the passenger/cargo area. If you have *that* option you will have a switch like this:

View attachment 73068
probably just to the right of your steering wheel.
And a plastic heater duct along your driver's side cargo area floor, against the wall.
It's not a second furnace, it's merely additional hot water plumbing and a fanned radiator back there.
(does NOT work with engine off)

--dick
Ah ha! Now I know! I have the timer (without the knob) and the Cargo option! Eureka!
 

Speed Racer

2006 2500HC Passenger Van
AND, at least on my 2006, the Rear Heat fan will not work without the engine running.

I don't believe that the MB bastardized controls do anything with the Espar heater as to a relationship with the temperature setting on the ATC. If the engine coolant temperature is below 167F (some claim 180F), when enabled, the Espar will run. The ATC temperature setting may control the cabin heat as to temperature, but I'm 99% certain that the ATC doesn't affect the Espar enable as to cabin temperature.

vic

P.S. - I'm certain to break that plastic heater duct in my 2006. :bash:
Don't know if my rear heat fan will work without the engine running, but next time I'm in the bugger, I'll find out and will post.

Guess I'm not quite ready to sit back and observe.

Thanks again,

Bill
 
Last edited:

Top Bottom