Our next rig

[booster]

We dealt with tank and other kinds of heaters at just about all my jobs that I had while working and they are always a problem. Any heater with bends tends to break at the bend but coiled ones do a lot better as they seem to spread out the stress a lot. Breaking at bulkhead fitting is also common.


Double wall/straight though tubes with leak detection were the most reliable and least likely to cross contaminate process fluids. Differential expansion rates from temp differences between the materials and temp gradients are not your friend.



How hot is your glycol going to be?


It think going to propylene glycol, if the lower heat capacity isn't an issue for you, is a very, very good idea.

[avanti]

Originally Posted by booster

How hot is your glycol going to be?

I think Espars output something in the range of 160-180 degrees F. However, the freeze-prevention loop has a dedicated tempering valve, so I can make it as cool as I like. Probably a constant gentle heat may be the ticket.

[GeorgeRa]

Originally Posted by avanti

I think Espars output something in the range of 160-180 degrees F. However, the freeze-prevention loop has a dedicated tempering valve, so I can make it as cool as I like. Probably a constant gentle heat may be the ticket.

Do you mix cold fresh water with coolant in your tempering valve in the freeze prevention loop?

[avanti]

Originally Posted by GeorgeRa

Do you mix cold fresh water with coolant in your tempering valve in the freeze prevention loop?

Trick question?

No. The "cold" side is the return glycol, just before it enters the Espar. So, yes, there will be a limit to how cool I could make it using this technique. However, the automation system will also be able to do a kind of "pulse width modulation" of the second loop, by turning it on and off periodically.

Some of these temperature points are already being measured, and I will instrument all of them eventually, so we will see exactly how it behaves.

[GeorgeRa]

Originally Posted by avanti

Trick question?

No. The "cold" side is the return glycol, just before it enters the Espar. So, yes, there will be a limit to how cool I could make it using this technique. However, the automation system will also be able to do a kind of "pulse width modulation" of the second loop, by turning it on and off periodically.

Some of these temperature points are already being measured, and I will instrument all of them eventually, so we will see exactly how it behaves.

No, it was a trick question, I just didn’t think that return coolant could be used as source of low temperature fluid in tempering valve. I am struggling to see how these flows from the pump and return will work/compete in tempering valve. A simple PWM will work.

[avanti]

Originally Posted by GeorgeRa

No, it was a trick question, I just didn’t think that return coolant could be used as source of low temperature fluid in tempering valve. I am struggling to see how these flows from the pump and return will work/compete in tempering valve. A simple PWM will work.

Here's the recommended plumbing diagram for two loops, from the Rixen's website:

rixens loop.png

[GeorgeRa]

Originally Posted by avanti

Here's the recommended plumbing diagram for two loops, from the Rixen's website:

Attachment 13861

Thank you, very interesting design, so the pump could primarily circulate freeze preventing loop trickling hot coolant as needed, thanks for sharing. It is obvious that plumbing is not my profession.

[avanti]

The body of the vehicle has no penetrations whatsoever anywhere below the porch lights at the roofline. Shore power is via a SmartPlug mounted on a small custom box in the rear next to the trailer hitch plugs:

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One of the biggest challenges was how to deal with the water fill port, the dual-dump setup and especially the permanently-attached macerator hose. Clearly, it needs to be outside the vehicle and must be conveniently accessible. Our GWV Legend had fiberglass running boards, but we weren’t going in that direction. ARV has a very nice solution built around nerf bars. Using this as inspiration, we searched for Transit-specific bars with an appropriate geometry that we could use as the starting point for a custom compartment. The only one we found was an item by Aluminess. Fortunately, it was a very nice product and served well for our purpose. The passenger side has an unmodified bar/steps. The driver’s side was heavily modified to form three locking compartments: one for the dump valves; one for the macerator hose, water fill, and switches for the macerator and a solenoid valve that configures the plumbing for winterization blow-out; and a small storage area:

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In order to prevent the macerator hose from freezing during winter use, the tank-heater glycol circuit loops along the back of the compartment in order to keep it warm inside the box.

The fresh tank filler port uses a nice system from a company called Aquor. Very handy:

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[GeorgeRa]

Nice work.

Did you mount your Smart-Plug horizontally to maintain factory road clearance? On my Sprinter I mounted the inlet vertically without reduction of the factory road clearance. Did you use aluminum box from McMaster I specified a while back on the Sprinter Forum? https://sprinter-source.com/forums/i...20#post-273290

I use Aquor since 2020 when they just introduced their product for homes. I like its simplicity. Is there a sealed separation between fresh water inlet and macerator outlet hose? it could be a possible source of contamination.

[avanti]

Originally Posted by GeorgeRa

Nice work.

Did you mount your Smart-Plug horizontally to maintain factory road clearance? On my Sprinter I mounted the inlet vertically without reduction of the factory road clearance. Did you use aluminum box from McMaster I specified a while back on the Sprinter Forum? https://sprinter-source.com/forums/i...20#post-273290

The Smart-Plug is mounted in a custom powder-coated box that CMI fabricated. Don't know if it aluminum or stainless steel -- probably the former. On the Transit, it would have extended down significantly if it were mounted vertically.

I use Aquor since 2020 when they just introduced their product for homes. I like its simplicity. Is there a sealed separation between fresh water inlet and macerator outlet hose? it could be a possible source of contamination.

Not in separate sealed compartments. However, the Aquor port has a sealed cap, and is mounted vertically well above the top of the trough containing the macerator hose. Plus, the end of the hose (which also has a sealed cap) is 3' away from the port.

[avanti]

Little by little, the van's automation system is coming on line. A few days ago, several of the many temperature sensors became functional.

Just for fun, here is a three-day snapshot of two of them.

This one is behind the refrigerator, intended to monitor for adequate ventilation in the condenser area. It shows the temperature over a three-day period, with the fridge turned off, and the van parked out in the open:

temperature-wall.jpg

The first day was sunny, and the other two overcast.

And, here is the same time period, measured from INSIDE the fridge:

temperature-fridge.jpg

Interesting how the insulation smooths things out. Also, note the several-hour lag time between the "outside" and "inside" temperature peaks and valleys.

Since I also capture the current consumption of the refrigerator and the freezer, it will be very interesting to quantify the relationships among ambient temperature, fridge/freezer temperatures, exhaust temperature, and cycle times.

Just a taste of what will be possible.

[Arlo]

Nice - useful and entertaining! Are you able to monitor the sensors from your house with a WiFi connection to the van? I’m generally curious about the van’s connectivity. Thanks again for the interesting posts.

[GeorgeRa]

It would be interesting to see an ambient overlay, especially when you reached 80F inside the fridge in overcast conditions.

[avanti]

Originally Posted by GeorgeRa

It would be interesting to see an ambient overlay, especially when you reached 80F inside the fridge in overcast conditions.

Knowing where to measure "ambient" outdoor temperature in a van is always tricky. Here are data from a sensor under the van (intended to measure the input temperature for the battery fan):

temperature-under.jpg

This was parked on a concrete driveway. I can't swear that there was zero sunshine those days. And, of course, breeze (or lack thereof) would affect this measurement.

[avanti]

Originally Posted by Arlo

Nice - useful and entertaining! Are you able to monitor the sensors from your house with a WiFi connection to the van? I’m generally curious about the van’s connectivity. Thanks again for the interesting posts.

Yes, both data and controls are accessible anywhere in the world, assuming that the van has connectivity. Home Assistant's UI is via web browser, so anything that can be done in the van can be done remotely.

The van's router has WiFi-as-WAN, so if it is parked at home (or near any other well-known network), it will automatically establish Internet connectivity.

I will cover networking in more detail later. Networking on the road is still a work in progress. There is an excellent 5G antenna on the roof. I have been intending to get a 5G modem when good ones become available. However, there is also Starlink to consider.

There is also the issue of power when away from shore power. I am hoping to come up with a scheme that can provide remote access within the 200 watt solar panel's energy budget. This will not be possible with everything on, so I will probably implement a "snooze" mode, where most data systems are powered down, but some tiny device always listening (or perhaps listening intermittently on a fixed schedule). Dunno yet.

[GeorgeRa]

Originally Posted by avanti

Knowing where to measure "ambient" outdoor temperature in a van is always tricky. Here are data from a sensor under the van (intended to measure the input temperature for the battery fan):

Attachment 14005

This was parked on a concrete driveway. I can't swear that there was zero sunshine those days. And, of course, breeze (or lack thereof) would affect this measurement.

So, your temperature inside the fridge was a few degrees higher (~79F) than under the van (~75F). Nice to have this data to improve or diagnose problems.

[avanti]

All modern high-roof vans have an awkward space above the heads of the driver and passenger, formed by the sloping "brow" above the windshield. This space is usually either left as an open shelf or made into a cabinet that looks promising but has a disappointingly-odd inside shape.

I have never found either of these to be very useful, so in this build I decided to try something new. Instead of storage, I decided to dedicate this space to wiring, control, and datacom/media equipment. In our previous van, we dedicated an entire cabinet (above the fridge) for this purpose, which took up a lot of precious space. Here's what we did this time:

The area looks like a storage cabinet:

IMG_6337.jpeg

but opening the door reveals a little control panel for the few physical switches and an area that contains the van's router and AV equipment (excuse the mess--not sorted yet).

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When I get a 5g cellular modem, it will also be there -- the roof-mounted antenna is just above this area.

The area behind the control panel is used for the main DC distribution and control wiring. In order to easily access this area, there is a large hatch under the cabinet:

IMG_6338.jpeg

Here are the main 12V distribution system and fuses. This is a good place to see the quality of the wiring, which is similar throughout the van--everything neat, accessible and labelled:

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The little puck-shaped things are Shelly WiFi LED controllers, which control almost all the lighting in and outside the van:

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This setup makes it very easy to modify the wiring and add new features as the systems evolve. The concentration of powered devices in the passenger-side compartment would tend to cause overheating, so there are several temperature sensors and fans which will provide ventilation as needed.

[ks@yvr]

Very nice job and great spot for the different systems.

[GeorgeRa]

I like a lot accessibility to wiring of your design. I don’t have as good as yours access in my van. My focus was to concentrate most of electrical wiring and components in rear left space. Tradeoffs.

The upper front cabin space gives me a head ache of contradiction between desire for more shelf space and head knocking by low overhead. A potential solution for us could be a tilting shelf which I am trying to design. The shelf will have high volume for night at lower position and low volume at high position for easy ingress and egress from the van on the road.

[avanti]

As I mentioned briefly before, CMI has an interesting methodology for taking a completely custom one-off design from concept to a finished rig. This is a bit of a challenge, since you can't really look at a similar van to validate a layout. Even upfitters who do significant customization tend to build out of pre-defined "modules", or at least to accumulate a catalog of basic layouts that are then evolved to meet the customer's unique desires. But every CMI build is 100% custom, so it is a challenge to validate a design before building it.

Their solution is what they call their "white wood" stage. Their interiors are generally built from A-A grade plywood mounted using custom-made steel and aluminum brackets. The process starts with 2D and low-res 3D cad renderings, intended mostly to allocate space. Somewhat amazingly, the next thing they do is to "mock up" the design using the same high-quality ply that will later form the finished interior. Doing this instead of cardboard or particle board does two things: It permits very high-quality walk-throughs very early in the process, and the mock-up evolves organically into the finished van. Here are some pics of the process:

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more in the next post...