Difference between H12 17kbtu pre-heater booster and HZ9, 18kbtu heater booster

[lockmedic]

I'm ordering my "dream van", and fitting it with exactly the options I want. One of those is the fuel fired heater. Existing 2007 NCV3 struggles to keep up heating both the cab and box when the temps get below about 40f.

I know I could just throw in an espar heater and call it done for 1/2 the price but I like having things integrated into the electronic architecture of the van.

Having trouble figuring out the fundamental difference between the two heater option codes mentioned. Dealer is not particularly helpful, I think they throw out from the hip answers without actually reading the literature or understanding how it works.

What I want is something that will preheat the engine/cabin prior to startup and provide boost heat when needed. I'm pretty sure that's H12:

In addition to the heater booster, with the auxiliary hot-water heater,
the departure time can be programmed in the instrument cluster using
the stationary heater button in the climate control panel on the multi
steering wheel.
The colors of the indicator lamps above the stationary heater button have the following meanings:
 blue: auxiliary ventilation is switched on
 red: auxiliary heating is switched on
 yellow: departure time is preselected
In ventilation mode, the climate-control unit actuates the blower motor and the indicator lamp in the
stationary heater button continues to light up in blue. The maximum ventilation/heating time is 50
minutes. The air is supplied to the interior through the existing air outlets in the instrument panel or
optionally H00 and H13.
Benefits:
 Comfortably warm interior
 Aids defrosting of the windows
 Protects the engine by preheating the coolant prior to starting
This system is particularly recommended for vehicles with engines which will be used in very cold climate regions. Since these engines are extremely efficient, their thermal energy may not always be
sufficient in extremely low ambient temperatures. With this option it allows for a comfortable level of
warmth in the cab. The stationary heating function allows the interior to be warmed even before the
engine is started, so when the driver steps into the cabin it is pleasantly warm right from the start.

versus HZ9:

The 18,800 BTU (5.5 kW) heater booster (for diesel engines only)
can only be activated when the engine is running. The heater
booster unit is a compact water heater that is connected to the
engine coolant circuit. The heater booster can be activated manually with the stationary heater button in the climate control panel
or automatically as required at an outside temperature of less than
32 F (0 °C). The indicator lamp in the stationary heater button continues to light up in red when the heating is switched on.
The air is supplied to the interior through the existing air outlets in the instrument panel or if optionally
fitted with H00 and H13. After the heater booster has been switched off, the coolant pump and the
burner blower continue running for approximately 3 minutes, then switch off automatically.
Benefits:
 Engine reaches optimal operating temperature quickly
 Faster heater response
This system is particularly recommended for vehicles with engines that will be used in very cold climate
regions. Since these engines are extremely efficient, their thermal energy may not always be sufficient
in extremely low ambient temperatures. This helps to guarantee a comfortable level of warmth in the
cab.

 

[Wrinkledpants]

It's the same heater, but one has a small electric pump that allows it to pre-heat the engine. The booster function shuts off the electric pump (coolant is circulated with the engine water pump), but it still runs to boost engine coolant temps. I see no reason one should by the booster vs the pre-heater. It will not add any appreciable heat to the interior unless you're well insulated and have the cab closed off somehow. I believe all diesel vans have an electric heater behind the dash that automatically kicks on when the coolant is cold and it's below 50 degrees or something. This way, you have instant heat while the engine heats up. Our H12 adds literally zero heat to the interior and we're fully insulated.

That said, this system will not help you keep the van warm when driving. It's made as a block heater (pre-heating) or to help get a cold diesel engine up to operating temp more quickly. We have the pre-heating option to allow easier starting when it's cold, but I'll be honest that I see very little different in engine heat up time once the engine is running. We'll occasionally use the booster function if we start the van way up on a mountain pass and spend the next 45 min driving downhill, but otherwise it's a fantastic block heater.

I believe there is an option for a substantially more Btu output that puts another D5 at the rear of the van. This is great if all you're doing is carrying people as this heater only works when the engine is running. And, it takes up a lot of floor space.

If you want to keep the rear warm - get the D2. I'm with you in that I love OEM integration, but that's not what this pre-heater/booster are truly made for. Heated seats, heated windshield, heated mirrors, pre-heater, insulation, and D2. You'll have the most comfortable and capable winter traveling vehicle. When we go to dinner in the van and the D2 is still running keeping the inside at a nice 74 degrees, it's amazing to walk out to.

 

[lockmedic]

Thanks for that wrinkledpants. . . I should mention that I'm ordering a cargo (although a pretty fancy cargo) but I want a comfortable box to work in year round. I spent about as much time in the back of my van as I do in the front.

I was planning to go with H88 (rear heater prep) and add a simple heater core/blower to the back somewhere. I'd get the factory rear heater but it limits my cabinet options.

Not sure what D5 and D2 are. . .sorry. You are correct about the aux electric heater that most vans have. . .my current NCV3 has it but even with it, the rear is not a comfortable temp in winter. Cab is OK.

What I want is something that'll work at idle to maintain a comfortable temp in both the cab and the rear of the van. It will be insulated. I don't think there's enough surplus heat from engine coolant to accomplish that, and I don't think even the high output alternator would be enough KW to keep it warm back there.

Sounds like I should just get the Espar for the rear and live with lack of integration.

 

[Wrinkledpants]

I would do the pre-heater, H88, and then add an Espar D2 for rear heat. It's a waste to idle the van for heat. The D2 is the size of a loaf of bread, can be run indefinitely, and takes very little battery or fuel to operate. The pre-heater will give you the ability to set a timer so the engine is warm in the AM, the H88 gives you options for a lot of different things (and good for resale), but the D2 will be your ticket to comfort in the winter. We run our D2 for days on end when we're winter camping. Set the temp like you do in your home and forget it.

 

[lockmedic]

I may skip the pre-heater if it truly doesn't provide much benefit beyond faster warm-ups. Seems like a rather silly $2500 option if it doesn't provide additional interior heating. . . MB really missed the mark there.

I added the aux fuel tap to the build anyway on the off chance I ever wanted to install a diesel generator, but that would most likely be something I'd only do after retiring the van in 10-12 years and repurpose it as a camper.

But in the meantime I suppose that's all I need to fuel the Espar, right? I've never used one, never seen one, only know of their existence. Assume they need an exhaust vent?

 

[4wheels]

I may skip the pre-heater if it truly doesn't provide much benefit beyond faster warm-ups. Seems like a rather silly $2500 option if it doesn't provide additional interior heating. . . MB really missed the mark there.

I added the aux fuel tap to the build anyway on the off chance I ever wanted to install a diesel generator, but that would most likely be something I'd only do after retiring the van in 10-12 years and repurpose it as a camper.

But in the meantime I suppose that's all I need to fuel the Espar, right? I've never used one, never seen one, only know of their existence. Assume they need an exhaust vent?

It does provide additional interior heating ( at least my 2014 and I even got remote control), but I'd say : skip it
Just buy 5kw Chinese 12v heater

Sent from my LM-V350 using Tapatalk

 

[dkbird]

I have both in my 2008 Dodge. At the time as I recall when i bought it new, one was used to preheat the glycol prior to start (with a remote, or you can set a timer) which nicely warms the block prior to start - it was pretty much standard equipment from the dealer in Canada. (The unit could not be purchased with a block heater at the time - don't know if this is now possible) As mine is a passenger van, the other heater was used to provide additional heat for the rear of the van. So there are two fired heaters. When it is really cold (like 20 or 30 below) the heater seems to run all on its own. I have been told that this is to keep the engine hot to reduce emissions???? It is necessary to keep the back hot though - as the engine does not generate enough heat otherwise. I am looking to replace my sprinter (maybe with a new one) and the dealer said it was a good idea to run this to warm the engine up quicker. It does result in about 2 mpg poor economy when its very cold though (or maybe it gets idles more then) Regardless they have not been troublesome in the 11 years i have owned this.

 

[KGB Pilot125]

I have the HZ9 in my 2014, makes a huge difference in how fast we get heat and the engine getting to temp when it’s reakly cold out. Like this morning it’s 13f out and I will be using it. I would have gladly paid the 2500 to have the H12 and I still might add an aux heater under the passenger seat. There is something comforting knowing that the engine is warm, the interior is warm, and you don’t need to scrape ice off the windshield.

Also don’t forget about the front windshield defrost option. I had that and the T1N version of the H12 with REST and rear heat and I kick myself everyday for not holding out longer for the right van to come along.

 

[Wrinkledpants]

Agreed. Love our block heater, even just for the purpose of pre-heating the engine.

 

[RFehr]

Kinda depends on climate. IMO, either the booster heater OR aux heater is near mandatory for frequent cold climate use (by cold I mean sub -18C/0F). In these temps, the booster absolutely makes a difference while driving - and the aux option yields a warm cab and engine prior to setting off.

There is no ‘plumbing’ difference between the two options - just one missing wire between the switch and D5, a different switch, and some coding changes in the ECU. Both have a small pump that activates when the D5 is running. It is reasonably well documented on how to DIY upgrade from booster to aux - shockingly easy.

The issue (also well documented) is that there is no way in a factory configuration to avoid D5 circulation through the engine block. Hence the factory config is a pretty poor ‘parking’ heater - and also poor if you want domestic hot water while parked. There are generally 2 solutions: (a) live with the factory aux heater (pre-heat block and a bit of cab, boost while driving), and add a separate system for parking (more on D2 vs D5 for this purpose later); or (b) you can ‘hack’ the factory aux option to perform better as a parking heater (and for DHW).

For (a), the real question is whether you need DHW or not. A D2 is an air only heater, D5 is hydronic and can be used for (indirect) DHW and rear air heating via a fan coil. I personally love the whole one fuel tank operation where all heat that I need comes from diesel one way or another.

The (b) hack is pretty fantastic - as you really don’t need more than a single D5 worth of heat for everything. In short, it involves:
- adding a 3-way motorized bypass valve allowing the factory D5 to completely bypass the engine block (I.e. all heat goes to space heating and DHW).
- adding some heating line from this bypass valve (under the hood) to the general area of the D5. Some say the H88 prep option is useful for this - i’m not convinced.
- adding a fan coil for rear heating, and optionally an indirect DHW tank. These can be in series (DHW first) or parallel - more on this later.
- adding some sort of controller to help manage the many heating options you now have. A PSM can mostly to it all.
- optionally adding a small 12V booster pump if you are locating the fan coil and DHW toward the back of the van.

Plumbing DHW and fan coil in series is simpler from a control perspective, but less flexible. I elected parallel piping and simple motorized valves on both the DHW tank and fan coil. This way, I can heat only DHW, or only the fan coil, or both as necessary. The 3-way bypass valve is deactivated by either the engine running, or the “pre-heat” signal. The D5 is independently activated by either a DHW demand or the fan coil (along with some logic based on if the engine is running and warm - I.e. don’t start the D5 for DHW if the engine is warm enough to do it). I have a SPST switch in the dash labeled “camping” which activates a number of controls (including starting the engine at high idle to charge house batteries if the charge drops too low).

If you opt for that small but popular Isotemp Spa 4 for DHW, there is a risk of the D5 overheating and shutting down (as the Isotemp can’t quite take 100% of the D5’s output with the bypass engaged. This is not a problem with a larger unit - but a larger unit takes up more space. There are means of mitigating - but they involve either more space or more complex controls. I have opted for a 6gal DHW tank with a larger heat exchanger and I’ve not run into this issue.

The factory run time limit of the D5 is left alone - as with the engine bypass the D5 can heat both DHW and the cab easily within 40 minutes.

 

[grinnelljd]

I have the H12 17,000 BTU pre-heater/booster and a Rixens Comfort Hot D5 hydronic system.

I use the H12 heater to preheat the engine coolant on cold Winter days. I can activate it manually via the dash switch, preprogram a start time, or use its remote to start it from a fair distance. The one thing I don't like about it is how it is restricted by Mercedes to NOT run at temps over 39F.

This pre-heater/booster, combined with the heated seats, and the electrically heated windshield, make for a much better Winer experience here in New England. Oddly, Mercedes didn't also offer a heated steering wheel with my model year van (2018).

I use the Comfort Hot D5 hydronic system for heat and hot water in the living area of the van. It does well in that capacity and I haven't had any real issues with it.

I've got space under my passenger seat where I could add a D2 Airtronic heater and have been considering it as a backup heater for my Winter trips, but then I'd essentially have three Espar systems in my 20 foot van; that has to be on par with hoarding cats.

 

[Nimpoc]

This is the exact thing I've been looking to find for AGES!

Can you please share more details about your 'b' hack?
- Most interesting is your control strategy. Specifically, what are you using to control the D5, valves, etc?
- A list of parts would be amazing.

I've got a similar set-up with HZ9 + H88. I've added a D2 since I couldn't figure out how to p0wn the D5, but would LOVE to use it for DHW!

Thanks,
M<

p.s. The best link I've found referring to the difference between HZ9 and H12:
https://sprinter-source.com/forum/showthread.php?t=26084&highlight=hz9+control

Kinda depends on climate. IMO, either the booster heater OR aux heater is near mandatory for frequent cold climate use (by cold I mean sub -18C/0F). In these temps, the booster absolutely makes a difference while driving - and the aux option yields a warm cab and engine prior to setting off.

There is no ‘plumbing’ difference between the two options - just one missing wire between the switch and D5, a different switch, and some coding changes in the ECU. Both have a small pump that activates when the D5 is running. It is reasonably well documented on how to DIY upgrade from booster to aux - shockingly easy.

The issue (also well documented) is that there is no way in a factory configuration to avoid D5 circulation through the engine block. Hence the factory config is a pretty poor ‘parking’ heater - and also poor if you want domestic hot water while parked. There are generally 2 solutions: (a) live with the factory aux heater (pre-heat block and a bit of cab, boost while driving), and add a separate system for parking (more on D2 vs D5 for this purpose later); or (b) you can ‘hack’ the factory aux option to perform better as a parking heater (and for DHW).

For (a), the real question is whether you need DHW or not. A D2 is an air only heater, D5 is hydronic and can be used for (indirect) DHW and rear air heating via a fan coil. I personally love the whole one fuel tank operation where all heat that I need comes from diesel one way or another.

The (b) hack is pretty fantastic - as you really don’t need more than a single D5 worth of heat for everything. In short, it involves:
- adding a 3-way motorized bypass valve allowing the factory D5 to completely bypass the engine block (I.e. all heat goes to space heating and DHW).
- adding some heating line from this bypass valve (under the hood) to the general area of the D5. Some say the H88 prep option is useful for this - i’m not convinced.
- adding a fan coil for rear heating, and optionally an indirect DHW tank. These can be in series (DHW first) or parallel - more on this later.
- adding some sort of controller to help manage the many heating options you now have. A PSM can mostly to it all.
- optionally adding a small 12V booster pump if you are locating the fan coil and DHW toward the back of the van.

Plumbing DHW and fan coil in series is simpler from a control perspective, but less flexible. I elected parallel piping and simple motorized valves on both the DHW tank and fan coil. This way, I can heat only DHW, or only the fan coil, or both as necessary. The 3-way bypass valve is deactivated by either the engine running, or the “pre-heat” signal. The D5 is independently activated by either a DHW demand or the fan coil (along with some logic based on if the engine is running and warm - I.e. don’t start the D5 for DHW if the engine is warm enough to do it). I have a SPST switch in the dash labeled “camping” which activates a number of controls (including starting the engine at high idle to charge house batteries if the charge drops too low).

If you opt for that small but popular Isotemp Spa 4 for DHW, there is a risk of the D5 overheating and shutting down (as the Isotemp can’t quite take 100% of the D5’s output with the bypass engaged. This is not a problem with a larger unit - but a larger unit takes up more space. There are means of mitigating - but they involve either more space or more complex controls. I have opted for a 6gal DHW tank with a larger heat exchanger and I’ve not run into this issue.

The factory run time limit of the D5 is left alone - as with the engine bypass the D5 can heat both DHW and the cab easily within 40 minutes.

 

[warx]

I'm still confused about the non pre-heater version below. On my builds it quotes at only $640. This makes me think it is like the D2.

Fuel-fired heater booster (18,000 BTU) $640

Is this option a way of getting a cabin air heater that can be run independently (with mods)? Way cheaper than an actual D2 if so.

 

[gltrimble]

I'm still confused about the non pre-heater version below. On my builds it quotes at only $640. This makes me think it is like the D2.
Is this option a way of getting a cabin air heater that can be run independently (with mods)? Way cheaper than an actual D2 if so.

The D2 is an air heater. Both the H12 and H9 are water heaters that use your HVAC to transfer a small fraction of heat to the van interior. The bulk of the heat from the H12 and H9 goes into the engine coolant. The D2 is your best option for interior heat. The H12 is your best option for heating the engine or for hot water heating. The H9 is limited and can only operate with the engine running. The H88 option adds additional flexibility in the plumbing.


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[gltrimble]

This is the exact thing I've been looking to find for AGES!
Can you please share more details about your 'b' hack?

- Most interesting is your control strategy. Specifically, what are you using to control the D5, valves, etc?

- A list of parts would be amazing.
I've got a similar set-up with HZ9 + H88. I've added a D2 since I couldn't figure out how to p0wn the D5, but would LOVE to use it for DHW!
Thanks,

p.s. The best link I've found referring to the difference between HZ9 and H12:
https://sprinter-source.com/forum/showthread.php?t=26084&highlight=hz9+control

For about $20 I modified the plumbing on my H12/H88 combo to dramatically improve the heating of my hot water. I basically added a simple $5 heater flow valve and some additional hose that allows the majority of the engine coolant to bypass the engine block and return directly to the factory D5. No electrical solenoids or wiring needed and no chance of damage to engine. Details are on my build thread “Baby Shamu”.

Sent from my iPad using Tapatalk

 

[jjmcclure]

Informative thread. Can the factory Espar be repurposed as a dedicated heater say if you removed it from a salvaged vehicle, installed it and ran it separately from the engine (so you would have 2 of these on board)? How do you think this would compare to a Rixen in terms of performance and endurance and (anyone know who subcontracts this part for MB?)...anyone done this ?

 

[Nimpoc]

I've contacted both Rixen and Espar and both claim the controller (PCB) on the factory D5WS used in both the H9 & H11 options is unique to the Sprinter, and isn't compatible with the aftermarket Espar controllers. I haven't found a clear way to take control for on-demand domestic water heating.

gltrimble posted the D5WS thermistor hack here:
https://sprinter-source.com/forum/showpost.php?p=780614&postcount=11

Here's the thread that talks about reprogramming an HZ9 to H12:
https://sprinter-source.com/forum/showthread.php?t=26084&highlight=H12+control

The only source I've found for a new H12 switch is here:
https://www.ebay.com/itm/New-Genuine-Sprinter-Switch-6395451907-639-545-19-07-OEM/293452759907

My plan is to basically do what gltrimble did, but first I need to get from HZ9 to H12...

 

[Nimpoc]

Update:
The dealer in Rocklin CA was able to contact MD-USA and get 'permission' to recode my 2016 with HZ9 to H12. I can confirm that I now have the setting on my dash, and can set three start times via steering wheel controls. The dealer also turned on the J51 option w/o me asking for it. Oddly, I still have the 'Range to empty' display. Total cost was 1/2 HR labor, or $95.

Per the instructions in the middle link above (reprogramming...) there is a difference in the wiring recommendation there and the Espar manual. Follow the link above, wiring Pin 2 on the new switch to Pin 2 on the heater connector.

Further, in addition to the new switch that I linked above from an eBay seller, you'll need the following electrical contacts (pins) from the dealer, and a decent crimper.

MB PN Desc Qty Cost
011-545-81-26 Contact SP 1 $4.46
008-545-63-26 Plug 1 $5.28
000-545-69-80 Rubber Rin 1 $5.61

I use this crimper with good success. Not as good as the Molex and Amp stuff at work, but has never let me down:
https://www.amazon.com/gp/product/B0195VXA10/

Good luck.

p.s. Now I'm trying to figure out how to program the PSM. I'd like to bypass the 39*F interlock, and just have a switch to turn on domestic hot water (DHW) like a Rixen system. Any suggestions / links would be greatly appreciated!

 

[gltrimble]

Update:
The dealer in Rocklin CA was able to contact MD-USA and get 'permission' to recode my 2016 with HZ9 to H12. I can confirm that I now have the setting on my dash, and can set three start times via steering wheel controls. The dealer also turned on the J51 option w/o me asking for it. Oddly, I still have the 'Range to empty' display. Total cost was 1/2 HR labor, or $95.

Per the instructions in the middle link above (reprogramming...) there is a difference in the wiring recommendation there and the Espar manual. Follow the link above, wiring Pin 2 on the new switch to Pin 2 on the heater connector.

Further, in addition to the new switch that I linked above from an eBay seller, you'll need the following electrical contacts (pins) from the dealer, and a decent crimper.

MB PN Desc Qty Cost
011-545-81-26 Contact SP 1 $4.46
008-545-63-26 Plug 1 $5.28
000-545-69-80 Rubber Rin 1 $5.61

I use this crimper with good success. Not as good as the Molex and Amp stuff at work, but has never let me down:
https://www.amazon.com/gp/product/B0195VXA10/

Good luck.

p.s. Now I'm trying to figure out how to program the PSM. I'd like to bypass the 39*F interlock, and just have a switch to turn on domestic hot water (DHW) like a Rixen system. Any suggestions / links would be greatly appreciated!

So how will you circulate the coolant with the engine off?


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[Nimpoc]

I'm trying to do what's basically outlined in the post above, option 'B'. Using the PSM module to coordinate changing the air temp sensor, closing ball valves to cut off the engine from DHW circuit, commanding the H12 to operate, running the second water pump, etc. Still trying to understand what the PSM is capable of, and what I need to program it.
https://sprinter-source.com/forum/showpost.php?p=832991&postcount=10

I think firing the H12 should run the electric circulation pump, even when the engine is off. If needed, which I think is likely, I'll add an additional pump like this in series.
https://www.ebay.com/itm/Auxiliary-...-VW-Jetta-Golf-Passat-1K0965561J/333407478657

That's the plan anyway...