Elgena-NC6 Water Heater Install

[adamwcordell]

Heyo,

Decided to use the long Holiday weekend to install an Elgena water heater in my van instead of having fun. Some parts were fun, some weren't you know how this goes.

Anyway, this isn't meant to be a detailed write up or anything, just for amusement.

Installed:
Elgena-NC6 Water Heated
Adjustable Thermostat: 30°-80°C (86°-176°F)
Size: 39x 22x 23cm (15.3×8.6×9”)
Weight: 2.8kg (6.3lbs)
Power Consumption: 12 Volt -200 W (16A)
Heating Time: 22 min ( 55°C 660 W)
Over pressure Safety: 3 Bar
Water Capacity: 6L (1.6G)

Van:
-4x4 7.3L PSD Sportsmobile
-E49 Layout

Resources:
-Lowes
-Home depot

Tools you probably don't have (or maybe you do):
-Pex clamp tool
-Pex crimp cutter

What did I do?:

I built a little platform (15.375 x 13.5"x.75" Birch) to house the heater and the pressure regulator. Wrapped the platform in vinyl to make it look like I knew what I was doing. This barely went on, I really didn't think it through, anyway looks alright.


Using some simpson strong ties (6x6x1.5 12 gauge) attached it to the cabinet under the sink.

Heater is held on with 1/4-20 bolts, might add a strap over the top of the heater.

Pressure regulator is held down using a U-clamp.

Flex line is all 3/8x5/8. Pex is 1/2", came standard in the van.

Once the heater was bolted in, I clipped the pex line and spliced in the contraption.

Still need to wire it up. Draws 16A. I don't know much about how the van is wired, so far have no plan for how I'm going to wire it. Very open to suggestions. Will be spending the week researching.

Wish me luck!



Step-by-step

• Took measurements, mocked situation up in FEMAP.
  
• Built a little platform (15.375 x 13.5"x.75" Birch with a 4"X1" notch in the rear aft corner)
• Wrapped in vinyl
  
• Bolted heater down with 1/4-20 bolts (might add a strap over the top of the heater)
• Pressure regulator is held down using a U-clamp.
• Ran 3/8 X 5/8 flex hose to the cold water inlet of the heater from the pressure reg.
  

Where does it go?

• Attached the heater using simpson strong ties (6x6x1.5 12 gauge) under the sink. About 10" from the bottom of the heater mount to floor.
  
• Cut existing Pex tubing out, from floor up to the faucet.
  
• Started mocking up tubing on the fly while crammed in uncomfortable space. All flex is 3/8 X 5/8. Was really hoping to only do this once.
  
• Tightened up all hose clamps
• Turned on the water and nothing leaked, well something leaked but it wasn't my fault and I fixed it pretty fast.
  

Now what?

• No idea. Need figure out an electrical plan.
  

[adamwcordell]

Below is a picture of the van from outside for context.

[Orv]

Personally, at 16A I would strongly consider going straight to the house battery or battery isolator, and giving it its own circuit breaker (or fuse). That'd avoid it creating a voltage drop on other circuits.

[ctb]

Excellent job! For taking on something your not sure of, but doing it anyway...AND adding the humor we can ALL appreciate when we do/take on any project...especially after...looks like a nice add. HOT water is the extreme luxury for washing hands, sponge bath, bits n pieces...Have even washed hair, shaved..the things that make boondocking super spoiled...love it!

[adamwcordell]

Thanks CTB!

Orv, I think you're right, best to not draw down the 30A circuit. Will figure out a way to isolate it.

[Scalf77]

I agree the 30 amp passenger circuit is a bad choice. Coming directly off the battery is better, than running a cable from the fuse panel on driver side. I am not sure what equipment you have, but even if you have an inverter (meaning 0/2 awg going from battery to inverter. Connecting to the existing panel for that load could be problematic, based on existing circuit breakers size.

If you come off the battery you should probably make sure to fuse before going thru the floor. This means the fuse should have some water protection. You can decide if you want to take this moment to put a fuse panel on the passenger side of to go just to your heater.

Now the ground wire can become problematic if you have plans for a battery monitor. If using a shunt based monitor all power has to go thru the shunt. Going directly to the battery would bypass the shunt. So in any event your ground wire needs to be planned so it goes to the load side of the shunt. So that means planning on the battery monitor install ahead of this. You could go directly to the frame for the heater and that should enable you to include it in the shunt path. You can run just a ground wire back to the "Main Ground" connection on the driver side. Again, how I would recommend doing this depends on your electrical equipment.

Now on to your water heater 200 watts or at 12 volts is 16.6 amps , at 12.8 volts it would be 15.625 amps. More importantly at 10.5 volts it would be 19.04 amps. So at a minimum I would consider that a 20 amp load , this is also what the 125% calculation would give 16 X 125% =20 amps. While voltage drop for a heater is not critical to operation, the drop would increase resistance and draw more power or heat, so for it becomes important.

You may also want to look at a timer switch and/or low voltage disconnect switch for this device. That way you wouldn't kill the battery if left on accidently. The possibility of controlling it with a battery monitor could also be a possibility. A couple of ways to handle that issue, comes down to how much you want to spend.

Feel free to PM, if you want to bounce some ideas of me.

-greg

[adamwcordell]

Oh man Greg, you've given me a lot to think about. I'll be trying to wrap my head around all of that in the next few days. Not sure I'm following completely but once I have a circuit in mind I'll post here and see.if it makes any sense at all. I like the idea of having a battery monitor. I really don't want to run another lead from the battery up through the floor on the passenger side.

I may have missed this in your response, I'll re-read, but are the major disadvantages to running power from the existing fuse box to the heater?

[Orv]

Originally Posted by Scalf77

If you come off the battery you should probably make sure to fuse before going thru the floor. This means the fuse should have some water protection. You can decide if you want to take this moment to put a fuse panel on the passenger side of to go just to your heater.

I'd actually recommend a 12V circuit breaker. Most auto parts stores carry them, you can get water resistant boots for them, and they're not that much more expensive than high-amperage fuse holders. There are both push-button reset and automatic reset varieties. For this kind of application I'd go with the push button kind. (In the past I've used the auto-reset type for "mission-critical" loads like headlights.)



For noise-sensitive equipment (a high-powered stereo amp or a radio transceiver) I might go directly back to the negative battery terminal or shunt. However in this case a good ground to the frame should be OK. I'd use a properly-sized ring lug under a bolt, with the paint cleaned away underneath.


All of these connections should have dielectric grease on them to prevent corrosion in the future. I use it on all connections in campers, because condensation means the interior is a damp environment, too.

Now on to your water heater 200 watts or at 12 volts is 16.6 amps , at 12.8 volts it would be 15.625 amps. More importantly at 10.5 volts it would be 19.04 amps.

That would be true if the load were constant wattage. However, a water heater is probably going to be a resistive load. 12/16.6=0.7 ohms (approximately) for the heating element. At 10.5 volts, it will draw 10.5/0.7=15 amps. This is only 158 watts, so it will heat slower. At 12.8 volts, it will draw 18 amps and produce 230 watts worth of heat.



Any resistance in your wiring will add to that 0.7 ohms, decreasing the current draw and making the water heater heat slower. (The heat generated in the wiring is wasted, of course.)



As in most automotive applications, you'll want to decide the wire size based on the voltage drop you're willing to accept. Unless your wire run is very short, this will probably be larger than the minimum size that can carry the current without melting down.

[Scalf77]

Originally Posted by Orv

That would be true if the load were constant wattage. However, a water heater is probably going to be a resistive load. 12/16.6=0.7 ohms (approximately) for the heating element. At 10.5 volts, it will draw 10.5/0.7=15 amps. This is only 158 watts, so it will heat slower. At 12.8 volts, it will draw 18 amps and produce 230 watts worth of heat.



Any resistance in your wiring will add to that 0.7 ohms, decreasing the current draw and making the water heater heat slower. (The heat generated in the wiring is wasted, of course.)

Agree, I should have finished my coffee before typing.

[adamwcordell]

Still thinking on the wiring.



Hung up on how the heater wired to the fuse box is not as good as having it wired directly to the battery. Only thing I can think is that it may overload the wire running from the battery to the fuse box. Also it'll create more losses due to transitioning from battery to fuse box, from fuse box to long run of wire to the heater.



If I understand this correctly appliances wired into the fuse box are in parallel. Fuse box is then wired to the battery. This is equivalent to just having multiple appliances hooked directly to the battery terminals in parallel?



So if you just think about everything in the fuse box as devices in parallel then you hook the heater to the battery wouldn't everything still just be in parallel?