Water Water Everywhere AND lots to Drink! XRV Lance Update 10 May 2026
Right up there with the Electrical System in Lance, the Domestic Hot DHW and Cold Water DCW systems are critical to providing us with a great living experience and complete “off grid” independence. Below is a screenshot from my 3D model of the water system in Fusion 360 with the key components labelled to help show what’s what. (click to enlarge this or any photo in these blogs)
Note: DCW is also referred to as Potable water meaning safe for human consumption and drinking but all the water in Lance is potable so I’ll refer to it as DCW. 
As you have maybe noticed from previous posts, I build all my systems twice; First as a 3D model in Fusion 360 and then once I have it all laid out with everything fitting and working I “just” build it ITL or In Real Life as the “kids” say. It all looks very simple when its all done but getting there was quite the game of 4D chess to get everything to fit relative to each other, not have any of the PEX pipes interfering with each other and so on. Happy to report that this layout worked very well upon installing it and the whole water system has been working very well for us.
After designing and building everything with 3D models first and then building IRL for so many years now I can almost not imagine designing or building any other way. It DOES take some time to build these highly accurate 3D models where I try to be +/- 1mm but this is where I get to try out all the alternatives and ideas and find out what actually fits and works. This way for the most part I make all my mistakes (trust me!) here before I cut, weld, drill or mount anything which is a HUGE time and cost saving compared to making all those mistakes IRL. I won’t say I don’t make ANY mistakes IRL but very very few compared to doing this IRL to begin with, or just with freehand sketches,
Though to be clear I certainly still do use a LOT of pencil and digital freehand sketches at the conceptual and planning stages. 
IRL or Real Life does still help sometimes when I can have the real parts in my hands as I’m working out the 3D model for the placement of components such as the brass mixing valve and the black circulation pump which are the key components of the heated floor system we now have in Lance.
To help explain that labelled 3D model at the beginning there are actually two primary and completely independent systems or functions that you are about to see me install. One is to supply all the Domestic Cold and Hot water to the sinks, showers and water outlets. The second is for our interior air heat which is provided by circulating hot Glycol solution through the loops of PEX piping you saw me install into the floor inside and also through the two “Cozies” which are little radiators with hot Glycol flowing through them and then thermostatically controlled fans blowing air through these radiators to heat up the air inside the HappyTat. We find that most of the time we prefer to just use the floor heat as this keeps our toes nice and toasty and yet the air up above our heads is pleasantly cool which for us is the Goldilocks situation. 
The heart of both of these systems is this Oasiz Zephyr diesel boiler from ITR International Thermal Research, a Canadian company based in BC and a company I am familiar with from previous builds. It is super efficient and barely sips diesel to power the boiler which internally has two separate loops; one for heating up the fresh water or the DHW circuits and the other separate circuit that heats up the non toxic Propylene Glycol solution, basically anti freeze, that provides the heat for the interior floors and air. 
This labelled illustration shows all the various inputs and outputs of diesel, exhaust (out the bottom), fresh water and Glycol.
To provide some bigger picture orientation this large view of the Drivers Side DS of Lance’s HappyTat showing the full Electrical System in the exterior compartment on the Front DS corner to the far left here and then the wide central compartment immediately behind it.
All these external compartments have their own locking doors and full aluminium diamond plate interiors keeping them all completely separate, secure and easily accessed and this is one of the best benefits of going with an ambulance box as these are all standard. 
I couldn’t seem to find a photo of the empty compartment when I started but this is what it looked like in all the very messy IRL when we were moving Lance down here to Nevada. I packed it this way because at this stage I was initially considering positioning the Oasis Zephyr Diesel Boiler (Olive Green box in the bottom rear corner) and the 40 USG white plastic Grey Water tank on the front. 
But as I modeled this up and focused on my priority for keeping all runs of both electrical wire and PEX water lines as short as possible it worked out much better to flip that initial layout around to be more like this with the Oasis Zephyr boiler at the front. 
You can see how well this worked from this shot further along with the installation where the vertical Red DHW Supply PEX pipe goes directly out of the Zephyr and up through the ceiling of this compartment where the Galley sink is directly above. The shower is on the other side of that end wall of this compartment so it too is a very short run for the DHW to get to the shower head.
I had thought about putting in a neat little DHW return line that allows you to turn on that hot water valve first to get the hot water up to the taps and shower but with these lines all being so short it works out that the hot water is there almost immediately so we don’t waste any water running it till it gets hot. So the design has worked out very well in day to day use. 
Installing the Zephyr involved quite a bit of work as it requires diesel supply and return lines which are going to come up through the two holes on the right here with the Black rubber gromets on them. Then there is an 1.5” steel exhaust pipe which comes out the bottom of the Zephyr (sitting up on its side in this photo) and then a SS muffler under the floor of the compartment.
Rather than install a separate diesel fuel tank I tapped into the main fuel tank on Lance by installing these two T fittings and valves, one for supply and one for return and then ran rubber fuel lines from these over and up through those two holes above into the Zephyr. 
Inside the Zephyr there is a 2nd mixing valve so that you can set the output temperature of the DHW to whatever degrees you prefer for both safety and convenience. So far it has been working out very well for us with almost instant hot water and essentially an infinite supply of DHW that makes long hot showers a breeze other than needing to keep the 100USG water tanks filled up. 
I designed the Zephyr lines to have this optional “summer loop” on the hot glycol circuit for the heated with the 3 way T valve on the Right that allows us to shut off the flow of he hot Glycol to the heated floor loops and the two “Cozies” that are small radiators with thermostatically controlled fans in them. 
For those curious, this diagram shows how the heated Glycol flow works such that by shutting off that 3 Way Valve the Glycol basically just makes a out and right back into the boiler and does not run any of it through the floor or Cozies in the summer. Of course the independent DHW circuit still works all the time with fresh cold water coming in from the main water tanks and coming out the DHW lines to the sink and showers.
On the rear side of this compartment I mounted the water pump that pulls water out of the two potable fresh water tanks and then pumps that through the three stage water filtration system beside it. 
We’ve been very pleased with the performance of the Kohree 7GPM 65 PSI 12Volt water pump. It comes with both the pump, inlet filter and accumulator tank rubber mounted on the thick Black mounting plate. The PEX line from the water tanks enters through the Black fitting on the far Right, into the screen filter then the pump and then the accumulator tank. 
and turns 90 degrees into this 3 stage water filter that takes out just about everything from dirt to bacteria before heading onward ………. 
…… to supply the various DCW and DHW components. 
We take the “belt & suspenders” approach when it comes to our drinking water also added the grey Acuva box and white cylindrical filter you see up top here. This uses a UV-LED light which disinfects microorganisms (bacteria, viruses, cysts) using UV‑C light, and then the Advanced Pre‑Filter also removes chemicals, metals, chlorine, VOCs, odors, and turbidity. 
The Acuva output goes up to this dedicated Drinking Water tap at the Galley sinks and puts out about as close to pure H2O as you can get. Been working really well for us.
Shifting over to the Glycol side of this system the heated Glycol exits the right side of the Zephyr and flows through these Red 3/4” PEX-A lines and then goes through the aluminium diamond plate wall into the Front Cozy mounted directly behind ……
…. as you can see IRL where it is mounted inside the toe kick area of the Galley drawers. It slides back several inches and tucks completely out of the way in the end. 
You can see better in this labelled screenshot of the 3D model. Glycol exits this first front cozy and flows back to the Rear Cozy and then is returned back to the Zephyr as I hope you can see in the 3D model. 
To get the best fit for the return line out of the Front Cozy I needed to modify it with this 90 degree copper elbow. 
and then mount a thermal sensor to the copper tube which connects to the thermostats in the Zephyr to control switching the fan On/Off when needed. 
All the wiring connects into the main Zephyr control box which may look a bit confusing here but is very well designed and easy to work with.
Completing the Glycol run for the heated floor loop, I mounted the 12V circulation pump just below the water pump so it has a direct shot at the 1/2” PEX-A floor loop supply line as you see here. When needed this pump turns on and pushes the hot Glycol through the whole set of loops embedded in the floor and then exits out that 2nd white PEX line and is returned to the Zephyr.
As you might notice I have my ever present Pixel tablet with my 3D model running so I can easily refer to that as I build out all the lines.
Last but definitely not least we wante to have an outside shower for times when we are in nice warm weather and in/out of the ocean, washing the dogs and so on.
i wanted this to be well protected and within the warm area to avoid freezing so I welded up this little bracket and mounted it to the to of the Water Systems compartment. 
This bracket allowed me to mount the mixing valve that is below this white flip up cover and the quick connect fitting for the shower hose on the Right. 
All very simple with braided SS lines for the incoming DCW and DHW and then ………
…….. the third line wraps around and feeds the quick connect fitting.
The two SS supply lines are T’d into the respective DCW and DHW PEX lines with shut off valves so we can turn them off when servicing. 
We may get a bit more “fancy” but for now plugging this coiled hose with a multi head garden sprayer on the end has been working very well for us.
OK, that’s a wrap for this week folks and hope it was equal parts interesting and informative.
Next post I will show you the recent build of the interior shower which has turned out eXtremely well too so be sure to stay tuned for that.
Thanks so much for spending time to join us here and thanks for your patience with my very irregular schedule of posts. Lance, Zoe, Razz and I are hitting the road next week to make the drive up to join Christine at our place on Saturna Island so my be more than a week till I can put together the next update but I’ll do my best.
As always, your comments and questions are VERY much appreciated so please leave those in the “Join the Discussion” box below and Ciao for Now my fellow adventurers.
-Wayne
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