Why is this wire this way, and dare I cut it? (12V water heater)

[mhiscox]

If it's going to be usable, I need to reduce the length of the 12V water heater I got for the XV-JP. Along those lines, I wanted to "remote" the thermostat and "using power" LED, putting them elsewhere with longer wires back to their terminals, thus eliminating the need for the beige lump at the end:

(Click photos for closeups . . .)



That seemed like a great idea until I found that the thermostat controlled by the knob was connected with the long coiled silver wire shown below. One end is stuck into the tank of the heater and the other is attached to the innards of the thermostat:



So the wire is apparently conducting a thermal or electrical input to the thermostat, and the fact that it's ten times longer than needed suggests a) that its precise length is important and b) that I'd ruin it if I cut it, even just to make it easier to run before I butt connected it back together.

If anyone knows exactly what's going on here and whether I have any options, please let me know. There are considerable advantages in having flexible thermostat placement, but not at the cost of trashing the whole heater. Thanks.

 

[Haf-E]

Hey Mike - that's not an electrical wire - its a small tube which is filled with a liquid of some type. The liquid expands and causes a small diaphragm to bulge which trips a switch - located in the small cube section at the end.

So it can be remoted - just don't damage the small tube and be sure that the position and connection means to the water heater stays the same. Its best not to mess with it to much. Also keep the uncoiled length of the capillary tube inside the vehicle and not exposed to real cold or hot - best to insulate it perhaps with a semi-rigid tube which would also protect it.

Let me know if I can help you out more -

Christopher

cfreitas@sunepi.org

 

[mhiscox]

Hey Mike - that's not an electrical wire - its a small tube which is filled with a liquid of some type. The liquid expands and causes a small diaphragm to bulge which trips a switch - located in the small cube section at the end.

Well, I'm certainly grateful I didn't charge ahead with my side cutters.

It's sad the proper explanation never occurred to me, but I'm a tiny bit pleased I had the sense to ask. Thank you very much for the prompt help, Christopher.

 

[Hill Bill E.]

Yep, the silver tube is the 'thermo-couple' (or thermal-couple)

It tells the T-stat when to turn on/off.

As mentioned, it should be fine relocated, as long as you can do it within the length of the thermo couple, and keep it away from heat/cold influences.

 

[4xdog]

Thermocouple or capillary tube? Looks more like a capillary to me, as discussed earlier in the thread.

Don

 

[Haf-E]

No problem Mike - glad to help. The end of it should slide out of the tube it is slipped into - I would take a sharpie pen and mark the amount inserted. I know on my fridge it is important to have it in just the right place.

Thermocouples actually use wire - but you cant really cut them either as they use two different materials in the wire which produce a slight voltage at the point they are connected depending on the temperature. They are used more for measurement and high accuracy industrial control systems.

The thermostat you have there looks a lot like the type used on some electric baseboard heaters - so it should not be too hard to replace if you do bugger it up.

 

[mhiscox]

It's worth ending this thread by referring people to the pictures of the heater install that can be found in Post 630 on the big XV-JP build thread (http://www.expeditionportal.com/forum/threads/51254).



Thanks to the contributors here, who saved me from messing up.

 

[Truefire]

Mike where did you purchase this style water heater from and what is the appropriate name for this type, not necessarily brand name, but type of? Also, where is the best place to locate one? And what kind of heated flow can be extracted on the outlet side, gpm? lps? etc;?

Thanks, Chris

 

[mhiscox]

Mike where did you purchase this style water heater from and what is the appropriate name for this type, not necessarily brand name, but type of? Also, where is the best place to locate one? And what kind of heated flow can be extracted on the outlet side, gpm? lps? etc;?

Chris . . . they call these things "hot water boilers" in Europe, where the broadest selection can be found. Elegena is a popular brand with several models:

http://www.elgena.de/produkte.htm

and I have the Nautic Junior. I had Steve at Eurocampers order it for me; if you have any contacts in Europe, they could probably get it over-the-counter at a caravan supplier. There's nothing special about it, and I would have preferred to have had a smaller version of the Isotemp heater originally supplied. But it seems like all of the US-sourced units are sized for fairly big boats, so I had to get a European model.

It's important to note that these units are tank-type units, rather than on-demand units that heat the water as it passes through. So I have 10 liters of hot water, delivered at whatever flow I want (controlled by the mixer on the sink faucet), and when that's gone, I have to wait for the next batch of water to heat up. I haven't used the heater enough to know what the recovery rate is (and I couldn't find a specification), plus I don't plan on heating a tankful unless I have an external power source (alternator or shore power), so I'm basically thinking I just have the 10 liters to use at each time.

FWIW, I had a wall-mounted propane-fired on-demand heater in my Unimog camper; it had about a one gpm flow rate with a 50 degree temperature increase. That worked great in the summer, but it'd only heat 40 degree water to lukewarm unless you slowed it to barely a trickle. But in general it was a good system. Unfortunately, they're pretty big things. The unit I ended up with for the XV-JP is pretty much the biggest unit that would work in my situation, where it had to fit on the floor behind the passenger seat. But if I'd had more space, I could have placed it anywhere, as the only connections required are the cord and two small water hoses.

 

[Truefire]

Mike I appreciate your detailed response. very helpful. I was hoping this was an on-demand heater. There simply is not anything like this on the market here in North America that I have ever discovered. I ended up buying my small on-demand heater from Puerto Rico but really need a little more water capacity flow capabilities. America offers only large, very cumbersome units which soak up way too much space. I am not sure why they do not offer a vast array of alternatives, for the technologies are certainly here to manufacture such. And I would dare say the demand is awaiting their births.

I would love to go the route of the propane fired heater but would not have any room left in my cabover to install the tank and heater. The site the link directed me to is great, just cannot read a dang thing it is saying.. a bit Dutchy!

Wonder if any on the home page there are indeed on-demand? Could you advise?

If not are those options available on the market over there? Also, if so are there contacts here on the forum that you might be familiar with that reside over there that would be willing to prepare and ship package for me, for reimbursement?

Thanks, Chris

 

[mhiscox]

I sadly don't have a contact in Europe--European ExPo members, there's a business opportunity here, I'm pretty sure--and Eurocampers is the only US group I know of making a business acting as the middleman.

All the heaters Elegena makes are tank-type. I did have an exceptionally good on-demand heater made by Precision Temp:

http://www.precisiontemp.com/showermate-m-550-marine-tankless-water-heater/

in my Sprinter camper, but it was a pretty big, and pretty expensive, unit. Sure worked well, though.

For what it's worth, my favorite place to see what's available in on-demand heaters is eBay. Go there and search for "tankless water heaters" and you'll get every size, shape and flow available. It's very helpful to use the units there to see the relationship between size and flow. Lots of small units with low flow and lots of big units with large flow; maybe there's something in the middle that would suit your needs. In all my looking, though, I haven't found anything magical. To produce good flow and a good temperature increase takes a sizable burner and a good amount of coil within the unit.

 

[AeroNautiCal]

The site the link directed me to is great, just cannot read a dang thing it is saying.. a bit Dutchy!

If you click here,, and then click on the Union Jack flag on the left, the web page language (mostly) changes to English. Then click 'Produkt', just below the flag and the product web page opens, then scroll down to the 3rd Boiler and click on 'Nautic Junior' and the English language 'Nautic Junior' web page opens.

(If using Firefox, you may have to click the Firefox 'Allow' button after clicking on the flag).

Hope this helps.