Hot Water Heat Exchanger in an LR3?

cmb6s

Adventurer
No, I'm not doing it... yet. Just wondering if anybody on here has attempted this? I'd really like to have hot water showers, but most of the solutions don't work well for me. A propane heater would probably work ok, but I'm trying to cut down on the amount of stuff I carry in the trunk - 2 adults, 2 kids (and every now and then the dog) along with all of our stuff takes up almost every square inch of space already. The simple solution, a bag you fill and leave in the sun to warm up, doesn't really work for me because if I'm in one place, I'm usually at a camp site with hot water anyway. If I'm on the move, I can't let the bag heat up...

I don't mind cold showers now, but as we dip into the chillier weather in the fall, I obviously start to mind more and more. And the wife would mind having a cold shower any time of the year. So, that's a no-go if I want to convince her to come out more often.

The most elegant (and complicated) solution would be an onboard heat exchanger. Specifically, I've been looking at a Helton or Bushranger, but was curious if anybody else has experience with these? I was thinking a good location to mount it would be in the location of the EAS reservoir, but on the passenger side. This is where the heater hose is routed to the rear anyway, so it would be easy to tie into the coolant system at that point. Thoughts? Advice? Would love to pick the collective brain on here.
 

DiscoDavis

Explorer
I bet you with the amount of heat the motor outputs you could do it functionally speaking. Who knows what kind of fault code apocalypse it might trigger however.
 

krick3tt

Adventurer
I have often thought of a heat exchanger but have not the talent to make it happen. If you do accomplish this it would be a wonderful thing. Please keep us informed of any progress you make. My LR & I would welcome such a thing.
Currently I use a garden sprayer (stainless steel) that can stand the heat, either pour it in or put it directly on the propane stove to heat about 2 gallons of water. Pressurize it and clean up. Tried the bag in the sun, on a cold day when the shower is most wanted it is a waste of time as there is more cold air than sun to heat the bag.
 

Ian_Barry

Observer
You want to get fancy?

I see that your interested in walking down this path, possibly with company. Fortunately we appear to be co-located in the mid atlantic.

My plans for this involve rerouting the rear heater lines into a plate heat exchanger, right before the (NAS) passenger side rear wheel. The water tank will go where the spare used to go.

Here's what I know:
- coolant temp is approximately 205°F @ operating temp.
- coolant flows (at least on my truck) to the rear regardless of the rear A/C settings (go ahead and ask how I know)

I don't want to locate the plate exchanger where the (ROW) reservoir tank would go, because I want to put a tank there for air. Also because I've already hacked at the lines in the rear wheel well it seems fitting to go back there for modification.

The big outstanding question is where to put the pump. My thinking it to locate it inside the cabin in my storage/sleeping platform. For that to happen it would be neccessary to route water lines into the cabin. I thought this could be done from the rear grommets or with a drill and new grommet at the rear; essentially entering at the right/rear interior panel (where the factory jack is located).

As to throwing codes; I'm relatively certain that it won't cause an issue. Assuming we only plumb into the coolant system there's no way the truck will even know that I'm stealing it's warmth. I suppose in theory it will reduce running temp ever so slightly. I see this as a nonissue.

Let me know what you're thinking and if you're interested in maiming your truck with me.

Cheers,

Ian
 

Gamester

New member
Fun project.
You might want to keep in mind the weight you'll be adding to the truck, with water weighing just over 8 lbs / gallon.
 

cmb6s

Adventurer
Hey Ian,

I love that somebody else is thinking about doing this! And it makes it even better than you're local. :)

I fired off an e-mail to Bushranger yesterday, asking if they could provide any data on the expected temperature rise vs. flow rate for their heat exchanger. This was their response:

"The max flow rate for the heat exchanger is 4.3L/M however the temperature that can be reached is subject to a large number of variables (listed below)
- Water temp in
- Ambient air temp
- Engine capacity of the vehicle – 2lt petrol compared to a 4.5lt V8 diesel
- Revs of vehicle to how fast the coolant flow is
- Coolant capacity of the vehicle
- Any smarts in the vehicle to regulate coolant flow
- Water flow rate through the heat exchanger
- Setup in vehicle (location is a major variable)
- Plus probably some I haven’t thought of at the moment
Feel free to call if I can provide any additional info. Apologies that I was unable to give you the answers you were looking for."

While true, it doesn't give me any comfort that this unit will provide what I need. The 4.3L/m is a good flow rate in my opinion. That would give just over 4 mins for a 5 gallon bucket of water which is plenty for a quick shower. However, I just have no idea what the temperature rise is for that flow rate. I'm not looking to add any more onboard water (I carry 11 gallons in a Front Runner container up top) like you are, but am thinking that I could just use whatever stream I happen to be near. We're blessed with plenty of water sources out here, but I might think differently if I was out west. However, that means that I could require a 40-45 degree F temperature rise at times. :p

The thing I like about that heat exchanger is that it has an inlet and outlet on each side (or so it appears), which means that it would fit great in-line with the rear heater hose. The Helton unit has inlet and outlet on the same side I believe, which is good for mounting vertically under the hood, but not so great for our use.

I may just end up building a mockup of the exchanger and see where it would actually fit when I have time. I agree with your location... somewhere down that right hand side certainly makes the most sense, though I seem to remember there was much less space as you approach that rear wheel. I have also cut and spliced my rear lines, so if I could tie into the point where it's already cut, that would be ideal. Guess I'll just get back under the truck and take a more detailed look...
 

morrisdl

Adventurer
I have a heat exchanger/hot shower in the boat the works similarly and considered doing the same to the LR3. I ultimately went with a much simpler solution: 5 gal Jerry can with a shower head. Harbor Freight has the cans for $30. When we camped near a water source, I filled it (left the cap off) and placed it 12" from the camp fire. It heated to 100F / 37C degrees in about an hour. Used a $12 I/R thermometer to monitor. I wired a 12V pump to mine, but it also worked fine on just gravity:

20170607_105427.jpg

5 gal was plenty for two showers. Having a camp shower is great! its like resetting the camping clock back to day 1.
 

DiscoDavis

Explorer
As to throwing codes; I'm relatively certain that it won't cause an issue. Assuming we only plumb into the coolant system there's no way the truck will even know that I'm stealing it's warmth. I suppose in theory it will reduce running temp ever so slightly. I see this as a nonissue.
What got me to mention the codes is one particular one is that when the thermostat delaminates and allows just a bit more coolant to flow and thus the loop runs just a bit cooler, it will throw a code and a CEL; P0128 - Coolant Thermostat (CoolantTemperature Below Thermostat Regulating Temperature). It will throw the code even just coasting down a short hill as the loop cools beyond what the thermostat can close to control, but perhaps with a perfect thermostat it can compensate for an extra heat exchanger. Interested to see how it would work.
 

cmb6s

Adventurer
What got me to mention the codes is one particular one is that when the thermostat delaminates and allows just a bit more coolant to flow and thus the loop runs just a bit cooler, it will throw a code and a CEL; P0128 - Coolant Thermostat (CoolantTemperature Below Thermostat Regulating Temperature). It will throw the code even just coasting down a short hill as the loop cools beyond what the thermostat can close to control, but perhaps with a perfect thermostat it can compensate for an extra heat exchanger. Interested to see how it would work.
Well that's just weird. The coolant is below operating temp every time you start the car up. So, you think that perhaps the code was thrown because the temp dropped and the thermostat was trying to close, but couldn't? I could see that, but I can't see throwing a code just because the coolant is below temp.
 

krick3tt

Adventurer
I do like the idea of the red can for a shower but it requires a campfire and often where we go there are bans for fires. That is why I got the Campfire in a can, its useable anywhere. National parks and such.
The idea of camping without a fire is not as appealing as some might think. It's just about the outdoor experience and that includes fire, but not one that can cause damage with ash and sparks. I was very old school until I tried it and now without having to carry or buy wood the trips are just fine and 'shutting down' or turning off a fire is a safer alternative.
This still leaves the 'how to' in respect to showers. So the sprayer (noted in previous post) is my go to plan now.
 

cmb6s

Adventurer
5 gal was plenty for two showers. Having a camp shower is great! its like resetting the camping clock back to day 1.
Lol. Yes! And also good for emergencies. When I was camping the other weekend, I must have been the last person to take a shower in the evening because by the time I got there, no hot water was left. I had my 22 month old with me and she was still in her swim diaper from dipping in the lake (for those who don't know, they don't seal well). As I got in the bathroom, I realized that she had soiled her diaper... badly. In fact, it had exploded out the bottom and gotten all over her leg. Well, with no hot water left, I was forced to take and give her a shower in freezing cold water. Credit to her, she didn't even cry. However, right after I had finished and dried her off, while I was drying myself off, she ran over to her soiled diaper and started smacking it with her hand. So... back into the freezing cold shower we both went for another round.

Sigh :rolleyes: Someday, I'll look back on this "character building" and laugh. :squint:
 

DiscoDavis

Explorer
Well that's just weird. The coolant is below operating temp every time you start the car up. So, you think that perhaps the code was thrown because the temp dropped and the thermostat was trying to close, but couldn't? I could see that, but I can't see throwing a code just because the coolant is below temp.
Right but when you start the car it's not expecting a certain temperature as opposed to it (the ECU) seeing a temp drop while at op-temp that it can't control.
 

zelatore

Explorer
I've done this as a thought experiment many times but never actually get around to doing it.

I work in the marine business, so I'm very familiar with small 6 to 12 gallon water heaters driven by a heat exchanger off a V8 gas motor's cooling system. Given some run time, it'll get every bit as hot as you can stand - at least the equal of the 120 or 240v heating element. Since this is typically only looped into one of the two motors, it lets you see the effect it has on the running temp. Normally I see very little difference in the engine temps, perhaps 5 degrees or so.

As for the stuck thermostat throwing a code, that is only after the truck has run long enough to be at temp yet does not get there. It knows better than to throw the code at start up. I do not think this would be enough to cause the code.

Much like the OP, I had figured I'd put a tank in the spare tire well as I carry my spare on a swing-out. There's plenty of room for 5 to 10 gallons of water there. Ideally you'd have a plastic tank made to your specifications including location of fill, exchanger, outlet, and vent lines. I have done a bit of looking but not seen an off-the-shelf roto-molded poly tank that looks like a good fit but I certainly have not done an exhaustive search. The other option would be a flexible bladder tank, placed inside a steel box you could fab easily yourself. I suppose you could in fact make your own steel tank, but I'd prefer a bladder inside as it allows for my possibly less than water-tight welding and prevents worries about rust. The bottom of the box would have to be of heavier material to serve as a skid plate, just as you'd need to make a skid to protect the bottom of a poly tank.

Heat exchangers are readily available form Amazon and the like in a variety of sizes. This would be plumbed into the existing coolant loop for the rear HVAC as previously discussed.

For a pump I'd use the smallest 12v marine unit I could find from Surflow, jabsco, etc. Given the limited amount of water the lowest volume pump available would be good. These are demand-sensing pumps so they only run when the tap is open. Mount a power switch wherever convenient; I already have a 6-ga power feed from my battery to a fuse block in the driver's side cubby area at the back of the truck so my power is already set. Just have to add that circuit. I'm not sure where I'd mount the pump but there's plenty of room under the truck or as mentioned behind one of the side access panels in the cargo area.

The fill would be a standard marine deck fill mounted into the upper surface of my steel bumper. These are typically 2", so routing the hose to the tank may be a challenge due to tight bends but again, should be possible.

The output would need to be a quick-connect fitting to a hand shower with an on/off switch at the wand. These are usually found through the RV world, though some overlanding specialist sell them as well.

The drawbacks: this design does not include a standard water tank, just the hot water tank. After a full day of driving the water may well be TOO hot for a shower. It would be preferable to have a cold tank passing water through a quick-exhanger system and a mixer which I believe is what the OP was suggesting. I don't know if this would deliver sufficiently hot water or not.

Without significant insulation for the tank, you couldn't use it below freezing. When running the heat exchager and proximity to the exhaust should more than keep the water thawed, but left to sit over-night or longer in freezing weather could be a problem. To that end, you would have to remember to winterize the system if you live or travel in cold areas.

As mentioned, water is heavy. While this does carry the water as low as possible, 5 gallons of water is 40 lbs. Call it 50-60 lbs by the time you add the extra hardware. More if you go with a bigger tank of course. And while low, it does carry the weight at the far end of the vehicle instead of between the axles which would be ideal. This isn't critical itself (the stock spare weighs more than this) but it's still a substantial amount of weight to add to your kit and these trucks are extremely heavy to begin with.

Though I've spent a fair bit of time thinking about this, in the end I never really can justify it. I just don't take that many long trips. I generally only do 1 or 2 trips of more than 3 days in a given year. I'm actually coming up on an annual week long trip in the Sierras next Saturday which inevitably makes me start thinking about this again, but again I just don't have enough need. This year I'll have 3 week-long trips but still, it's not reached the critical level of need.

For now, I have a road shower mounted on the roof rack. It's far from perfect and on cool or cold days doesn't get hot enough, but I can always run out a gallon or so of the warm water, boil it on the stove, and add it back in to get to the desired temp. I've mod'ed it with a quick-release fitting for the hose, made my own longer hose, and added a better spray head. It still has the drawback of forcing you to take a shower right next to the rig, so you make a muddy mess where you'll be loading/unloading the truck but for the few times a year I need it it's enough.
 

Ian_Barry

Observer
Hey Ian,

I love that somebody else is thinking about doing this!
I will do my best to post up the information that I've collected so far - please bear with me though, I'm in the midst of moving.

My memory is telling me that 20 plate exchanger will work brilliantly - check DudeDiesel for easy to read information and then cross shop it on Amazon/Ebay.

When I last stopped planning I was trying to figure out how to insulate the water as I camp year round.

Talk soon,

Ian
 

jeegro

Adventurer
I am in the process of adding hot water to my D2. I started a build thread in the general vehicle modifications forum.

Since the GPM of the coolant system is only 3-6 GPM, I went with the duda-diesel 10 plate exchanger. I plan to use u-bolts and secure it to the frame rail. Shurflo pump. Honeywell mixing valve. I couldn't find a suitable under-car water tank yet, so I am starting off with the front runner 45L roof rack tank to see how it goes.
 
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