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Old 08-09-2016, 09:47 AM   #1
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Join Date: Jun 2016
Location: Denver, CO
Posts: 242
Espare airtronic/flat plate vs Hydronic

Looking to figure out a system for our Sprinter 4x4 build. MB has a factory option to run coolant lines to the back of the van to be used by the upfitter for plumbing in an aftermarket radiator or water heater. They just connect the line together and leave it up to the upfitter to handle the rest. Given the cost and complexity of a Hydronic unit for coach heat, we're considering doing the MB heater lines option with a flat plate attached for showers, and then an airtronic for coach heat. With the factory block heater (Espar unit), we could run that for the flat plate or just idle the engine. At this point, we only see hot water being used for showers.

Hydronic Pros:
- Not dependent on Sprinter motor
- Can route the coolant lines under the floor for in-floor heating.
- Coolant lines are smaller than forced air hoses.
- Expensive
- Takes a long time to start pumping out heat
- higher energy consumption
- more complicated install

Airtronic/flat plate Pros
- Use existing Hydronic heater on engine block that is under warranty.
- Airtronic makes heat faster
- much cheaper
- Dependent on engine for hot water (block heater won't fire above 40 degrees F, runs only an hour, would need to idle otherwise).

Our van will have windows front to back and in rear doors. It's a high-roof and will have winter insulation. Will be used a lot in really cold, high mountain environments. My feeling is that the windows will make for more volatility in temp swings given how poorly they act as insulation. This is where the quick reacting airtronic might make sense, but at the same time, floor heating might help from the hydronic unit.

Anyone have any feedback on this? It's a $2500 price difference.

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Old 08-09-2016, 10:34 AM   #2
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Join Date: Apr 2013
Location: San Francisco, CA
Posts: 2,448
We put the Airtronic D4 in our pop top and love it.

Considered the Hydronic D5 but passed because of complexity, noise!, electrical demands! and damage to a flat plate when in freezing weather. Cost was a consideration, but would not have been a deal killer, if function had prevailed. In an insulated (windows covered with some insulation) fixed top rig, the D2 maybe sufficient and for a couple of hundred more than the D4, you could get two D2's.

Ducting for the D4 is 3" out of the unit but can be flattened to an oval if space is that constrained. Two outlets or even one central out let with deflection capability is all that is needed. I was pleasantly surprised how well the heat distributed from one central vent on the floor even with the top up and zero F outside.

There are other solutions for hot water if all you want it for is hot showers.

Beastie 3: 2002 7.3 EB Cargo: Agile TTB, CCV Mid Top, Custom Walk Through, Lots of stuff added.
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Old 08-10-2016, 09:55 AM   #3
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Location: Denver, Colorado
Posts: 129
Wrinkledpants - over on the Sprinter Forum consensus among owners with the factory diesel block heater option seems to be it's worthless for anything beyond basic cold weather engine preheating. In other words don't expect it to fulfill coach water or space heating needs. Part of that's probably the control temperature limitation you mentioned above.

Full disclosure - my information is secondhand from past Sprinter forum discussions, our Sprinter does not have the factory Espar option.

Webasto Dual-Top diesel furnace/water heater would be a good alternative but I don't know if Sportsmobile will install it. I have a co-worker with the Dual Top in an Outside Van and loves it.
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Old 08-10-2016, 10:01 AM   #4
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Location: Denver, CO
Posts: 242
Thanks - that was the general consensus I got, as well. Plus, last night my wife is washing her face and I dabbed my tooth brush in the running water to find that it was hot. I asked if she thought she'd want hot water in the camper for washing her face. We sat staring at each other for a minute before she said "aaaah yeah I think we should do the hydronic option," lol.

I suspect we'll be glad we did it.
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Old 08-16-2016, 01:35 PM   #5
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Join Date: Feb 2008
Location: Normandy Park, WA
Posts: 364
We have both the Airtronic for heat and the Hydronic & flat plate for hot water. The Airtronic is great for heating and we use it a lot and it has been great. We have only had to service it once so far which was to replace the atomizer screen (normal maintenance)

The Hydronic and flat plate are great for hot water but I would not want to use it for heat. The pump is too noisy to be used while you are sleeping and it seems to have a pretty heavy draw on the battery. I don't know the specific current draw but I would definitely suggest researching it before making a decision.

I hope this helps.
'08 SMB 4X4 6.0PSD EB 50 (96K)
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