Diesel heater retrofit in an Interstate

[InterBlog]

We have mentioned this in passing, but we have never devoted a thread to it - the possibility of swapping the Interstate's propane furnace for an Espar or competing product that taps the diesel tank and thus greatly reduces reliance on the Interstate's problematically-limited propane supply.

THIS IS AN INTERSTATE TOPIC, NOT A GENERIC MH TOPIC. There are technical considerations that are unique to Interstates, limitations that impact the potential range of functionality of the Interstate as a hardened cold-weather vehicle. So I respectfully ask that no poster reply with, "Oh, that topic belongs in the general motorhome section." No it does not. The sizing of the unit, the wiring of the unit, the placement of the unit, the management of unprotected components such as exterior water lines... these are all factors that are specific to the Airstream Interstate van. For those reasons, this thread belongs here in the Sprinter and B Van child forum, thanks.

LB_3 and I are now considering this retrofit. No decision yet, but thinking seriously about tackling it. We are in the research phase.

Let me get this thread ball rolling with a paste of some extremely useful observations that Mark (Lotus) made in April 2020 on another thread that was not specific to the issue of the heater itself, and where these comments were not further explored at that time. I've added some contextual enhancements to the original wording for the benefit of those who are not as familiar with the technical shorthand employed in Lotus's original post:

***

"I’ve considered a diesel fired hot air heater. The stock Espar heater on the T1N AI will warm engine/heater coolant and works off diesel. It uses the [elevated] tap to [the main diesel tank and therefore it] cannot [accidentally] use all the engine fuel [potentially leaving the Interstate owner stranded].

It is mounted under the bonnet [hood] and not particularly quiet, it is fine in its location. I would likely mount is under the van- after fabricating something to keep it out of the weather (well, my initial thoughts anyway).

For colder weather- it would certainly be nice. The T1N has limited propane and the propane furnace is pretty [noisy] too. Plus [the propane furnace is inconveniently located] under the bed (when in use) in the model I have. It is way easier to just fill the [diesel] fuel tank [than to be continually refilling the too-small propane tank] - and from the specs I read it would not use that much [diesel fuel].

I have not been using [my Interstate] in the winter much for overnights (just day trips) lately, so I have not really pursued it.

Another thing to consider- at least on my older model, there are water lines outside the van that are not heated and no easy way to heat. I’m not sure if this is true for newer ones- although I suspect the outside shower at least could be troublesome."

***

[Lotus54]

When I was looking into this- I found ducting was readily available allowing mounting the heater itself under the van without any huge deal. Of course, a hole would be required in the floor.

An alternative location is under the passenger seat. My battery is located there, but other models are not and of course you have an entirely different battery system. Noise under the passenger seat may be an issue (?). But if mounted underneath, and the ducting coming up under the seat- it could be a pretty clean installation with the output going down the ‘hall’ between the seats perhaps.

Maybe I’ll start looking into this again also.

[InterBlog]

The noise has been a concern to me. There are many videos on installation, but no useful ones that I have found yet on operation, so that I can get a feel for the noise. Some videos compare the ESPAR D2 to cheap Chinese knock-offs in bench tests. They are all loud on the bench. One of the reasons I have waited to consider installation is to see whether the manufacturers improve the sound profiles.

I think we would go for an under-seat mount. We’d lose our safe, but we could potentially put one where the propane furnace is right now. As long as the swivel continued to work, that location would be OK with me.

My husband would prefer it under the passenger seat, and for some reason, he is winning a lot of marital squabbles right now. I think I am saving up for a big put-my-foot-down moment to come my way.



The issue with this heater conversion is that we don’t need it, but if the moment arrives when we WOULD need it, we would REALLY need it.

COVID-19 changed the “need” equation. One of the pandemic’s enduring lessons is that it does no good to have money in the bank when lifestyle doors are slamming shut. What if there was an emergency and I had to go to Nova Scotia right now? I don’t have the Interstate cold-weather capacity to handle that scenario, and I sure as hell cannot get on an airplane like in the “olden days”. What good is money in the bank if my few remaining options for some facsimile of normalcy are taken off the table? We save for a rainy day. Well, it’s been friggin’ pouring for about 8 months now.

[Hittenstiehl]

"Ourkaravan" has done one of these heater's.

He reminds us of you (super builder) though we don't know any of you

We'd also like to emulate his cabinet style some day.

[InterBlog]

Originally Posted by Hittenstiehl

"Ourkaravan" has done one of these heater's.

He reminds us of you (super builder) though we don't know any of you

We'd also like to emulate his cabinet style some day.

That guy is *a-maze-ing*. He has told his story publicly - his young wife died of illness, leaving him father to a baby daughter who he is raising on his own. The van he built is their bonding platform.

[Lotus54]

One install description I read talked about installing a muffler for the exhaust that reportatly cut the noise quite a bit.

https://www.bunkheaters.com/Exhaust-...-24mm-P56.aspx

You probably already have a very similar heater in your AI, but it heats the vehicle coolant. You can listen to see how noisy it is. I have mine setup so I can run it without the engine running, it does put out quite a bit of heat and is great for defrosting/defogging the windscreen. It takes awhile to get up to temp- and I’m sure much heat than a direct to air into the van would be. Plus it takes more DC power, since it runs the heater fan to distribute heat.
With the unit outside, it is not very loud inside- but of course it is way up front, the heater fan could make more noise.

This is a pretty good step-by-step inside install (newer van I belive)

https://radvanadventures.com/2017/02...ion-diy-guide/

[Hittenstiehl]

IB, agreed, Amazing!! And what a story.

[Lotus54]

Well...never said I was smart.
My furnace fan has a noisy bearing. And while it works quite well, I need to remove it anyway to fix.
So...I am ordering and Espar and going to put it right where the original furnace is located. If it is too noisy, I’ll move it under the vehicle somehow. But I’ll bet it won’t be any louder than what I have.

I’ll post up some pictures and results of my lunacy.

Here is the installation manual

https://www.butlertechnik.com/downlo...Diagrams_1.pdf

[InterBlog]

Originally Posted by Lotus54

...
So...I am ordering and Espar and going to put it right where the original furnace is located. If it is too noisy, I’ll move it under the vehicle somehow. But I’ll bet it won’t be any louder than what I have.

.....[/url]

FWIW, my prelim research pointed to the Airtronic D2L. Supposedly its ergonomics are better than the previous D2 iteration.

The users manual you posted suggests that the M2 is "recreational" whereas the S2 is commercial. It's not clear to me why vanners choose the D2L.

My main question at this point, unresearched:

If the engine's OEM Espar beneath the hood connects to the diesel tank via the supplementary connection (the one that will not allow total tank exhaustion), how are you going to pipe this additional unit? Is it required to drop the diesel tank and add connective hardware to it?

[Lotus54]

I think I can just tap into that same line, before the ‘other’ Espar pump.
At least that is my hope.

The nomenclature on the unit I got is S2 D2 L

I had a hard time finding a source that listed the exact differences between of of the models- more than just the obvious ones like higher output.

Next I need to see how many bolts to remove the jacknife couch. That will make installation a lot easer.

BTW, the space to the rear of the furnace could be a good safe location. There is nothing currently there except empty space.

[InterBlog]

We have never liked having the furnace under the beds while they are folded down. It leads to a much larger-than-necessary temperature gradient from floor to ceiling because the air cannot circulate efficiently.

Also, if the Espar is put there, isn't it going to blow hot air directly at the opposite under-couch bin which is only 18 inches away?

I think there is a nozzle of sorts to direct the hot air, but it doesn't go as far as to rotate 90 degrees - for instance, to send the air up the hallway.

[InterBlog]

Here is a good general assessment of the 3 main combustion heater brand choices in the market segment that is relevant to vans. It was apparently published just a few days ago.

[Boxster1971]

Originally Posted by InterBlog

Here is a good general assessment of the 3 main combustion heater brand choices in the market segment that is relevant to vans. It was apparently published just a few days ago.

Interesting article - but I sense a bit of confirmation bias by author since they have a Propex propane heater. The author claims better US customer support for Propex, yet the Propex web page only has six dealers in USA. I think there is much more support available for Espar and Webasto since they are also preferred for truckers and marine/boating use.

Also the comments are informative. This article was written in 2018, but just updated.

[Lotus54]

The included outlet vent is adjustable for direct. I plan on making sure it points up the ‘hall’. I can think of numerous ways to do that.
Depending on how it work, I could also put a duct that takes it along the ‘hall’ and then up- when the bed it ‘made’. Of course, something removable would require storage.
I’m thinking if it points straight down the ‘hall’ when the bed is down it will work pretty well. Even popping on a small 90º adapter for night time would be easy and simple to store.

At least that is my thought.

[InterBlog]

Originally Posted by Boxster1971

Interesting article - but I sense a bit of confirmation bias by author since they have a Propex propane heater. The author claims better US customer support for Propex, yet the Propex web page only has six dealers in USA. I think there is much more support available for Espar and Webasto since they are also preferred for truckers and marine/boating use.

Also the comments are informative. This article was written in 2018, but just updated.

Good point - I hadn't read the comments.

Like most other aspects of Class B ownership, this decision is influenced by user habits. If someone wants to upgrade their heater because they spend a month every winter at high elevation on domestic ski trips (lower 48), maybe diesel isn't the best choice for them.

I, on the other hand, face the continuing impossibility of procuring propane in eastern Canada. So for me, the choice could scarcely be more clear, if I want to travel there during cold weather and remain sane.

A diesel heater would reduce my Nova Scotia annual exclusion window to about four months (December through March) - that because of snow pack. I would be able to navigate public roads just fine, but my property's road is private, so there's no plow service. Even if I purchased plow service (which many landowners do), the road grade is too steep for the Interstate if there is any snow or ice present.

Edit: Over on Class B Forum, a couple of dudes were advocating for the use of kerosene in diesel heaters. I get that there could be operational efficiencies with that approach, but nobody would touch the question of where and how kerosene could possibly be stored in a body-unmodified van.

[Boxster1971]

I’ve also been following the discussions about diesel heaters on the Class B forum. I plan to go with diesel or gasoline hydronic heating in my next B-van. It will either be on a Sprinter or Transit van. There also a lot of discussions on diesel heater on the Sprinter forum. Many of the threads on using kerosene appear to focus on occasional use to give the unit a cleaning tune-up.

Using kerosene exclusively seems counter productive to the main advantage of have all your fuel in the vehicle tank. Apparently the additives in automotive diesel and gasoline can cause deposit buildups in these heaters - thus requiring more maintenance than a clean burning propane unit. Bio-diesel blends, so common in USA, are often cited as causing issues.

[InterBlog]

Originally Posted by Boxster1971

.....Many of the threads on using kerosene appear to focus on occasional use to give the unit a cleaning tune-up.
.....

Lotus, you got that? If you are going to tap into the existing Eberspacher engine unit line, does it make sense to also put some kind of a valved pig tail on that new line segment, so that one could occasionally suck up a bit of kerosene for this maintenance purpose?

[Lotus54]

Originally Posted by InterBlog

Lotus, you got that? If you are going to tap into the existing Eberspacher engine unit line, does it make sense to also put some kind of a valved pig tail on that new line segment, so that one could occasionally suck up a bit of kerosene for this maintenance purpose?

Not a bad idea- it would be pretty easy to do when installing I think. Might be nice to have for using a separate diesel container for some reason.

I just got the Espar, I have not even opened the box. I will need to take some time to figure it out- and I need to get a plug for the propane too. (Initially right were the furnace is- then if I leave the Espar in that location I’ll seal it up where it splits under the van).

[InterBlog]

Originally Posted by Lotus54

Not a bad idea- it would be pretty easy to do when installing I think. Might be nice to have for using a separate diesel container for some reason.

I just got the Espar, I have not even opened the box. I will need to take some time to figure it out- and I need to get a plug for the propane too. (Initially right were the furnace is- then if I leave the Espar in that location I’ll seal it up where it splits under the van).

We are waiting with bated breath, obviously.

And I am not-so-secretly thrilled. Much of the time, LB_3 and I go first on any given envelope-pushing exercise in the Interstate context. This time, someone else is doing the snow-plowing. Which leaves us in this mood, LOL (I'm represented by the dog - a female dog):

[don000]

Having replaced my AI with a 'self-upfitted’ Sprinter 2500 I no longer follow this forum, but saw this thread on the weekly AIR Forums newsletter and thought I’d respond in gratitude for all the advice I received here in the past.

I installed a diesel-fueled Webasto Air Top Evo 40 amidships inside under a couch, and could not be happier with the performance of the unit a year later. I cannot understand how people can say this unit is loud, compared with the Suburban unit in the AI.

The unit is controlled remotely with a Webasto Smartemp Control V2.0, which could account for the way it operates. Startup takes a little while as the dosing pump builds up fuel pressure, but in operation the unit spools up and down very smoothly as output is regulated. At low output it is very quiet. If the van is in motion, I generally need to put a hand at the output duct to determine whether it's in operation. The heat output seems noticeably more even and diffused than with the Suburban unit in the AI. It can be ducted to multiple outlets if desired.

I’ve not measured electrical consumption but it seems quite low. Before installing my lithium system I ran both the heater and a large Dometic CoolMatic CRX 1400 off the factory auxiliary battery through multiple cold nights with no problem. Fuel consumption also seems low, hardly noticeable on the gauge or in mileage figures.

The worst part of installation was making sense of the wiring, but tech support helped through deficiencies in the product literature. The key is to buy the overpriced harness adapter, Webasto 5012138A. The other key is to use a vacuum pump (e.g. Mityvac) to pull fuel through the dosing pump to the unit before startup.