Only cold water?! We're not barbarians!
As Brad of Drive Nacho Drive put it, we're soft. We're not burly, tough people. Hardcore outdoor people we're not. Instead, we wince and whimper when confronted with things like slightly cool water. On our two-week trip, our shower was your basic solar shower. It seemed like a great idea - we live in the very-sunny west, so it should work great, right? Humboldt has a handy bucket on the top (stock forward luggage compartment), which is perfect for the shower to soak up all of that solar energy. One problem - when the shower is constantly cooled by 60-70 mph air, the solar energy doesn't really get you anywhere. We found out the hard way that the water typically wasn't very warm by the time we wanted to take a shower. Warming up some water on the stove isn't a huge deal for a short trip, but it would be a little inconvenient for a longer trip.
In short, we needed a water heater. I spent many sleepless nights stressing over what to do. How should we heat the water? Engine coolant (essentially free energy)? Propane? Something else? Should we build our own heater or buy something? If we buy, should it be a tankless system or a normal water heater with a tank? What about the extra weight? Here's my thinking on the different options:
HOME-BREW COOLANT SETUP:
Essentially free energy. The coolant's going to be hot anyway, so we might as well use it to heat our water.
More balanced weight. I would put the water tank outside of the van, below the right side (essentially opposite the stock propane tank).
No giant hole in the side of the van.
The biggest issue was that we didn't want to have to idle the van to have hot water. We needed some goofy plumbing to properly bleed the coolant system, which means that the engine doesn't run very warm and it takes awhile to get there. Point being, we'd have to idle the van for a long time in order to take a warm shower - not to mention the inefficiency of burning gasoline to heat up water.
TANKLESS WATER HEATER:
More efficiently warms the water than a typical tank heater (using propane).
May or may not require a giant hole in the side of the van.
It only runs on propane.
It wouldn't physically fit in the place I had picked out (to the left / rear of the fridge).
Mighty expensive. The cheapest one was about $700 for just the water heater alone.
MARINE TANK WATER HEATER:
Fits nicely in the available space.
Well insulated (according to the marketing materials).
Runs on coolant and 120V AC.
No giant hole in the side of the van.
Would need to be mounted on the already-heavy side of the van.
Awkwardly sized for our available space. It would've fit fine, but the drawers above the water heater would've been pretty heavily compromised.
For our purposes, it basically only runs on coolant (I don't anticipate having 120 very often). Hence, it has all of the same issues as the home-brew setup but with better insulation and worse fitment.
RV TANK WATER HEATER (specifically the Suburban SW6DEM):
Runs on coolant, propane, or 120V AC.
Fits (mostly, more on that later) in the place I had picked out.
Lets us carry six more gallons of water (mostly, more on that later as well).
Not light (40 lbs empty), plus it's on the already-heavy side of the van. The six gallons of water it holds adds another 48 lbs, Full, that's almost 100 lbs more. Ouch.
We can't really use the extra six gallons we have to carry around.
Needs a giant hole cut in the side of the van.
In the end, we went with the tank water heater. It's not a perfect solution, but it should work quite well for us. That's the hope, anyway. It solved the problem of inefficient heating (the water gets heated every time we drive) while also letting us have hot water if we've been parked for awhile (propane). I doubt we'll use the 120 option often, but if we're in a campground with hook-ups, we'll be able to heat water without running the engine or burning our limited propane. How did I install it? Well...
First, I had to make the water heater the right size. Everything I found online said that it was 19-3/4" deep, which was just barely the right size. Unfortunately, everything I found was wrong - it was more like 21". However, the water heater itself was the right size, it was all of the extra pieces that made it too deep. The circuit board (protected by a giant plastic box), the 120 hookup box, and the too-long coolant barbs were the problem. I relocated the circuit board (still in its box) to the left / rear side of the water heater, removed the 120 box and rerouted the wires (paying attention to chafing), and cut the coolant barbs short. The coolant barbs were a little looser than I thought they would be, but with decent hose clamps they're not going anywhere.
Next, I cut a hole in the side of the van - by far the most terrifying part. I removed the middle cabinet, removed some of the super-thin plywood behind the cabinet, then cut out the insulation. I pushed the water heater into position, marked it out, and cut it. I drilled tiny holes in the corners from the inside, then connected those holes with a hacksaw from outside. Time-intensive, but it worked. I didn't want to use any power options for fear of burning the paint.
After cleaning up the hole and painting the bare edges, it was time to actually fit the water heater. First, I cut a piece of 2x4 to fit into the slot between the body and the metal lip a few inches inside of the body. The allowed me to fasten the water heater to this wood, which would hold it in place against any lateral forces. There are straps that hold the water heater down, to keep it from bouncing around.
Fitting the water heater door to the exterior should've been pretty easy, but the body of the van curves away, unlike the RVs this water heater is intended for. That... complicated things. I could've just shoved it out the hole, but it looked terrible. I could've come up with some sheet metal to fill the gap, but that would've only been a solution for the water tight part of the equation - not the ugly part of it. In the end, I trimmed the sheet metal of the water heater body to (roughly) the contour of the body, tweaked the door to fit and that was it. Simple to say, pain to do. Once I had the shape right, I painted the door Assuan Brown (my local NAPA mixed up a rattle can of the stock paint). I'd say it turned out pretty well in the end. I'm a little concerned about the long-term seal with the caulk I used, so I might put some sealant on it as well. The caulk is what's used on all (as far as I know) exterior RV accessories (such as a water heater), but it's intended to be used on flat surfaces and small gaps. It's like Play-Doh, so it's easy to make it thicker, but we'll see how it works long-term.
I plumbed the whole system in vinyl tubing. I wanted something that was easy to route and resistant to the vibration of being on the road - copper tubing wouldn't cut it. I secured the tubing as needed and ran it forward to the sink (check out the write-up on the faucet) and the rear shower (also with its own write-up). Pretty straightforward.
We also needed a different water pump, since we had to push water through the water heater, not pull from it. I was hoping to fit that inside of the new cabinet that houses the water heater, but that wasn't possible. It's unfortunate that it has to take up more space under the rear bench seat, but there was no other way to do it. Fortunately, it doesn't take up that much space. I'll build an aluminum box around it at some point.
Project cost: $760.
The water heater was by far the most expensive part - $427. Naturally, a couple months later the same water heater was on sale for $100 less. Nuts. The water pump was the next most expensive at $56. Otherwise, it was all fittings, paint, switches (one for the pump, one for the water heater), etc. It adds up quickly.
Hot water! Hot water for showers. Hot water for dishes. Hot water for hand washing. Hot water for showers. (If my wife were writing this, she'd wax eloquent for days about hot showers. She's the main reason I did this. I'll have her write her own soliloquy once it's been used for awhile.) Stay tuned for how well it works, but initial impressions are good.
Cost, weight, giant hole in the van. The most annoying con is that we can't really use the extra six gallons we're carrying around. Since water only comes out of the water heater when the pump is able to put water into the water heater, once the water tank is dry we can't get to the six gallons still in the water heater. Somehow, I didn't realize this would happen, although it's obvious in hindsight. Regardless, I'd like to put a three-way valve in the inlet for the water heater. The theory is that I could easily drain the water heater this way. This would also allow me to block off the water heater altogether. Say we're really low on water - we drain the water heater, put it in the main tank, and shut the valve going to the water heater. We would then have six extra gallons, although it would be awkward to do that. Short of having a second pump and setting it up to pull water from the water heater (I'm not sure if the pump could even handle hot water), I think the valve setup is our only option. I expect it to be very infrequently used, but better safe than sorry - right? I'm still contemplating that one.
The verdict: Awesome! I need to see what our weight (and weight distribution) is like. We definitely didn't do ourselves any favors there, but I'm hoping it will be okay. We can no longer complain about taking cold showers or warming up dish washing water on the stove, so I'd call this one a win.
UPDATE: We used the hot water heater for the first time last week. It was amazeballs. Seriously. Worked like a champ, made hotter than hell water, and we took showers in the desert! Still struggling with how much water to carry - wondering if we need to add an extra tank or not - but in the meantime, we have a fully-functioning shower on our van. Ahhhhh-mazing.
HIS UPDATE: I was really, really pleased with how well the water heater worked. You have to drive for an hour+ to get hot water, but it gets really hot. It makes sense - water heaters are typically around 130°F, but the engine coolant is about 180°F. Hence, the coolant will (eventually) warm the water to 180(ish)° F. That means you don't have to use much of the hot water in order to get comfortably hot water. It also means that you have to be careful to not scald yourself, but I'm okay with paying attention to that.
Possibly the best benefit was how long we didn't have to run the propane to get warm water. We typically don't need very hot water, so between that and how quickly it warms water, we only had to turn it on a minute or two before we needed to do dishes. With the auto-ignition, it's simply a matter of flicking the switch and (almost) immediately having hot water. Long story short, we couldn't be happier. There's the water capacity question, but that's a separate issue.