Water heating, in a vehicle

Dzl

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I dont think so. When I said "keeping this as vague as possible", another way I could have said it was "keeping options open". IDK if you took offense to the term "vague", it sometimes has a negative connotation for some, not my intent.
I didnt take offense, I just got the impression I was frustrating you with the lack of detail. And definitely yes, it is both vague, and an attempt to keep options open/remain flexible/see what is possible.
The OP was just really difficult to work with. Its boundaries were far to broad.
Yeah its one of those situations, where the 'blank canvas' is both a blessing and a curse (in that it allows so much flexibility, but also leaves so much open its hard to narrow things down).
Without direction you start getting ideas for space heating, which by the sounds of it is not something you are looking for.
Not space heating with a water heater, possibility of space heating with some of the sources that heat the water (somewhat common in marine, and some vehicle build niches (Skoolies, Overlanders, Boats) to use the engine cooling system for heat, and/or an auxiliary diesel hydronic heater for both water and space heating). For me, I like the idea, but I'm not sure I can justify the cost/complexity if there are simpler solutions that would meet my needs (needs = sink for dish/hand/face washing, wants = occasional showers or at least hair washing maybe).
 

eXodus

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I’ve thought about RV hydronic in a trailer before. An anti-freezed loop through tubing under the floor heated by exchanger from whatever one chooses, OR perhaps even a dedicated heater/tank with solar, fossil, or “other” inputs as options. Nothing manufactured achieves the goal perfectly if at all. The unit posted above is the closest I’ve seen but I don’t like the forced-air component- though I suppose the fans may be less wattage than I micro circulator. Dunno.

For on-the-go the propane demand tankless water heaters are surprisingly low cost to run and many models are <$200 US$.
For multi fuel options the price goes up. Vehicle coolant heating isn’t exactly ’free’ though I suppose some efficiency is gained by using the cooling system “waste” heat.

Another way of harvesting ’waste’ watts while driving could be a 120VAC alternator dedicated to a ~10gal electric water heater. As with coolant heat (watts, BTUs) there is a cost in fuel mileage albeit probably higher for mechanical energy creation. On the other hand, at steady-state and particularly flat-ground travels and “city” or urban travels internal combustion vehicles produce more horsepower (watts) than the load of maintaining speed. In other words the heat produced at low or mid part throttle exceeds the heat needed to drive at constantly varying levels. So an alternator load can ‘use’ that tiny difference, and when it requires horsepower to turn the alternator the percentage load is probably so small an effective difference may not even be noticed in fuel mileage.

The amount of waste BTU of heat coming out of a gas engine is mind blowing. Take the KW of your vehicle times 2 that's what the radiator is capable to release to the air.

So a 300hp truck can produce about 400kw of heat under full throttle.

Lots of untapped energy
 

Dzl

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Different question, so do you need cold water
I'd have to think about that, i'm inclined to say yes (drinking water).
You cold also insulate your primary water tank with a 2 inch foam boards and heat up the whole thing with a hydronic heat loop from the engine. Depending on the volume, you only need start the engine every other day.

A water heater is essential a second small tank.

Further stick an aquarium heater pad underneath to heat with electric in case you want.
Now this is some out of the box thinking. Without numbers it would probably be hard to assess the viability of the approach. But its certainly an interesting idea/concept. Especially for someone who drives a lot and lives in a temperate or warm climate. It would capture waaay more of the engine waste heat than a small water heater could.
 

Dzl

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I will definitely look into that little 1.6G heater, this is smaller than I was looking at, but if I were to rule out showers, I think that size could meet my needs (and realistically an indoor, plumbed, shower is at the very edge of realistic for the size of vehicle I am looking into anyways. And an outdoor shower could be accomplished with something like what @noenegdod has, or an eccotemp type propane portable shower.
 

eXodus

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I'd have to think about that, i'm inclined to say yes (drinking water).

Now this is some out of the box thinking. Without numbers it would probably be hard to assess the viability of the approach. But its certainly an interesting idea/concept. Especially for someone who drives a lot and lives in a temperate or warm climate. It would capture waaay more of the engine waste heat than a small water heater could.
An friend of mine has a diesel generator (charging batteries) and uses the coolant to heat up a 500 gallon water reservoir. Which then heats their house for a few days.

Just, adapted the concept to mobile.

Spinning the idea further, solar thermal works excellent with low temperatures. Not suitable for a small tank but for the large one it could just work.

Just run a black metal pipe around the roof edges with a small DC dump which only turns of when a certain temperature is reached
 

noenegdod

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Another way of harvesting ’waste’ watts while driving could be a 120VAC alternator dedicated to a ~10gal electric water heater. As with coolant heat (watts, BTUs) there is a cost in fuel mileage albeit probably higher for mechanical energy creation. On the other hand, at steady-state and particularly flat-ground travels and “city” or urban travels internal combustion vehicles produce more horsepower (watts) than the load of maintaining speed. In other words the heat produced at low or mid part throttle exceeds the heat needed to drive at constantly varying levels. So an alternator load can ‘use’ that tiny difference, and when it requires horsepower to turn the alternator the percentage load is probably so small an effective difference may not even be noticed in fuel mileage.
This is an interesting line of thinking, I'd like to explore more, I've never had a great comprehension of the ins and outs of alternator charging and its effect on fuel economy.

This is not correct. Any parasite you put on the crank shaft will increase drag and increase fuel consumption. Simply adding a second alternator on the crankshaft that does not produce power will simply by being there, increase fuel consumption. Bending the belt around the pulley and drag through the bearings even all the way down to air resistance on the surface of the longer belt all increase fuel consumption.

Using extra unused capacity of the alternator that is existing is a different story but is still a distant second best to utilizing wasted energy such as waste heat and excess solar.
 
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12VoltInstalls

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WOULD NOT work for the other two or three in the RV. A 1.6 gallon hot water shower and then finish with the cold water would be out of the question
That’s one of the nice things about the propane tankless water heaters: hot water now, every time, without limit.
 

12VoltInstalls

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This is not correct. Any parasite you put on the crank shaft will increase drag and increase fuel consumption. Simply adding a second alternator on the crankshaft that does not produce power will simply by being there, increase fuel consumption.
If you are driving and ‘wasting’ fuel at part throttle there are periods when the horsepower (watts) produced by the motor cannot be less and have the motor still run… so there is ‘free’ power available

Remember the Caddy in the 80s with the cylinders that would drop out to boost mileage?
Remember Bruce Crower experimenting with half-cycle V8s?
Remember Smokey Yunick?

There are several vehicles today that drop cylinders in no-load situations, to avoid burning fuel without a purpose.

I am not incorrect. It’s not the alternator isn’t a load that uses gasoline, it’s that sometimes it doesn’t take more gasoline to run an alternator depending on the driving conditions.
 

grizzzman

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Smokey Yunick was an amazing forward out of the box thinker. Ah the old Caddy 4-6-8 ( That was a pile of crap )
 

acdoctor

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So if you reduce the engine heat by much you will affect the mpg. Using a alternator requires horsepower. Like running A/C cost mpg. Or is it redundant you want? I once built a heat exchanger to heat water entering water heater. It captured heat from the shower drain. My self built RV I used tankless Lp and cook with it as wall. Last year we used it for 9 days in March plus 5 three day weekends plus I lived in it for 10 days cooking and showered all on half a 20 lb LP tank. I have never spent the money on hydronic vacuum tubes,but as good as they are said to be thrown a few on the roof 3 pumps, 2 plate exchangers and valves and you could have engine waste or solar.
 

noenegdod

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If you are driving and ‘wasting’ fuel at part throttle there are periods when the horsepower (watts) produced by the motor cannot be less and have the motor still run… so there is ‘free’ power available

You are never "wasting" fuel at part throttle. Are there better ways to approach the consumption of fuel than low throttle operation? Yes, but this has nothing to do with an alternator using any kind of "free power". The whole concept you are presenting defies logic. If there was extra power available to drive an alternator using the same amount of fuel, is in contradiction to the law of conservation of energy. It does not happen.

Remember the Caddy in the 80s with the cylinders that would drop out to boost mileage?
Remember Bruce Crower experimenting with half-cycle V8s?
Remember Smokey Yunick?

Cylinder deactivation has nothing to do with any kind of "free power". It is not free, it is simply a strategy to partially reduce pumping losses that occur during operation. By holding intake and exhaust valves closed on some cylinders, you reduce the pumping losses. It is nothing huge but it is noticeable. You can gain MPG by pumping your tires up harder and reducing rolling resistance. It does not mean you found free energy. If you disconnect the field windings on the alternator you will increase you MPG as well, but there is no free energy. The ultimate application of cylinder deactivation is accelerating under the most fuel efficient load and then disengaging the engine from the drive train and turning it off entirely while coasting down and then repeating the cycle. That will buy you a lot better economy than simply turning a few cylinders off.
There are several vehicles today that drop cylinders in no-load situations, to avoid burning fuel without a purpose.

Under no load situation, cylinder deactivation can be used to improve the distance a vehicle coasts but the biggest savings in fuel consumption is the fact that the ECU cuts fuel off entirely. There is no fuel entering the engine at all. The tuning is very simple. When throttle position = 0% and engine RPM > 800-1300 RPM, injector pulse width =0.

I have never tuned an engine that used cylinder deactivation but it would be similar to a honda with Vtec and the strategy would be similar. It is simply a bunch of if then conditions and when they are all true some cylinders valves remain closed and all the incoming air and fuel go to the active cylinders and the energy required to open the valves and compress the charge of air for those deactivated cylinders is reduced. There is no magical free energy that can be tapped into. It is simply a reduction of energy required to rotate the crank that results in lower fuel consumption.

I am not incorrect. It’s not the alternator isn’t a load that uses gasoline, it’s that sometimes it doesn’t take more gasoline to run an alternator depending on the driving conditions.
I am afraid you are. The only time an alternators electrical output is not proportional the additional fuel it is causing the engine to consume is when the vehicle is coasting and it is using its kinetic and gravitational energy to rotate the engine and drive the alternator, but, that fuel was simply burnt before the no throttle condition and stored as kinetic energy and is now being converted into electrical while no more fuel is being burnt and will cause the car to not coast as far as it otherwise would. It still isnt free.
 

Dzl

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So if you reduce the engine heat by much you will affect the mpg.
But realistically how much water or space would you have to heat to reduce engine temperature to the point that is relevant?
(I dont have the slightest clue, but I suspect its much more than a few gallons).

Or is it redundant you want?
Redundant, yes, but the main goal is efficient use of available energy sources (minimizing use of consumables like propane/diesel, or renewable but limited energy sources like solar).

I once built a heat exchanger to heat water entering water heater. It captured heat from the shower drain. My self built RV I used tankless Lp and cook with it as wall. Last year we used it for 9 days in March plus 5 three day weekends plus I lived in it for 10 days cooking and showered all on half a 20 lb LP tank. I have never spent the money on hydronic vacuum tubes,but as good as they are said to be thrown a few on the roof 3 pumps, 2 plate exchangers and valves and you could have engine waste or solar.
Very interesting approach! Was this part of a recirculating shower system, or just an innovative standalone way to extend your propane?
 

noenegdod

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Not space heating with a water heater, possibility of space heating with some of the sources that heat the water (somewhat common in marine, and some vehicle build niches (Skoolies, Overlanders, Boats) to use the engine cooling system for heat, and/or an auxiliary diesel hydronic heater for both water and space heating). For me, I like the idea, but I'm not sure I can justify the cost/complexity if there are simpler solutions that would meet my needs (needs = sink for dish/hand/face washing, wants = occasional showers or at least hair washing maybe).
Using either a diesel or propane heater you can heat water. Good system for cooler outdoor temps when you need space heat, sucks for summer use when you will end up heating up the vehicle a bit too.

One of many videos on the subject:
 
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noenegdod

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So if you reduce the engine heat by much you will affect the mpg.

Engine temperature has a small affect on fuel efficiency. The bigger issue from the tree huggers point of view is that if you run coolant through the hot water tank it will take longer after a cold start for the engine to reach operating temperature and will take longer for the catalyst to light off and emissions to improve.

If using this approach you would want to have a system in place that monitors engine temperature and does not start pumping coolant to the water holding tank until operating temperature was reached. Then, a pump would kick on and only a small amount of coolant would be circulated to prevent the temperature of the engine from dropping. If it were to drop a couple of degrees, the pump would turn off and wait for operating temperature to be reached again.
 

noenegdod

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Very interesting approach! Was this part of a recirculating shower system, or just an innovative standalone way to extend your propane?
This has been done in residential for 15+ years. There are lots of commercial units available and tons of DIY instructions on YT.
 

Dzl

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This has been done in residential for 15+ years.
The shower water heat reclamation concept? I was not aware of its use in residential systems. I have heard of similar concepts with air intake/exhaust though.
 

Dzl

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Here is an example of the type of water heater system (just the engine coolant portion) I am curious about (I don't feel the guy in the video is the best ambassador for the technical pros/cons of the system, but its youtube, comes with the territory).


And a basic diagram
calorifier-connections-vert.png


An alternative (that I have not found a diagram for, but would like to) is to use a heat exchanger between the engine cooling system and the water heater heating loop, rather than tying directly into the engine cooling loop. I think this would be preferable in some regards (leaving your engine cooling system as untouched and unmodified as possible).
 

Dzl

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@Dzl - did you use an Electroductus BMS/monitor in the end? How does his water heating solution using diverted excess solar pv fit into your musings?
That project was shelved/put on the backburner before it had the chance to make it out of the early planning phase, but, I may be approaching a point where I can start down that road again, at least I'm starting to think harder about it again, but it is still TBD.

His DSSR20 w/ diversion concept, is a big part of what inspired the musings (the general idea of using excess energy or heat when its abundant, and the specific idea of using excess solar to heat water). His DSSR20 with diversion and a 24V heating element (or actually I think maybe he reccomends 36V) is one way to approach this. And is one way I would consider addressing the solar side of things. But as with all things Dacian (Electrodacus), I'd have to make sure the other aspects of my system fit in with his design model enough for it to make sense. One of the marine water heaters I was looking at could accomodate both a DC heating element and engine heat exchanger with minimal modification.

When I was planning on using the SBMS0 I was planning on using it in conjunction with Victron MPPT's not his DSSR20's. But the diversion functionality is intriguing. However, I believe a somewhat similar outcome could be achieved in a slightly different way using the Victron MPPT's load output (or a Victron BMV), or basically any other controllers with load outputs where the voltage could be set. I haven't looked into this sufficiently, and I'm not sure of the pros/cons of each approach. Also I believe Dacian is coming out with a new revision to the DSSR pretty soon "DSSR50" (I've been pretty out of the loop lately).
 

pollenface

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I used 3x 10a immersion water heaters connected to an anderson plug outlet.

I could heat my 9L bucket of shower water in about 10mins
 
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