Electric supplement for Webasto

Len Silva · February 20, 2007, 09:59:54 AM

I'm considering adding an electric water heater in the Webasto loop to use the campground power that I'm paying for to try to reduce diesel consumption. Any thoughts?
I'm thinking a small 10 gallon unit but replace the low (1500) watt unit with a 4000 or so. It could be arranged to provide 2000 watts at 110V or 4000 at 220 if available.

Len

H3Jim · February 20, 2007, 10:09:10 AM

Why not? Do you you have a specific model in mind? Its just buying it and hooking it up to your system. do you spend that much time in campgrounds that you can get payback on your investment?

Nick Badame Refrig/ACC · February 20, 2007, 12:30:29 PM

Hi Len,

Atwood makes a marine water heater that is both electric, and has a hot water loop for your wasbasto

About $280.00. they also make larger one's......

Atwood Model EHM6

EHM6/110volt AC w/Heat Exchanger

Nick-

H3Jim · February 20, 2007, 01:19:36 PM

Nick, I think that one comes with a 1500 watt heater. Len needs something much heavier as that 1500 watts won't make dent in heating anything else but domestic hot water.

Nick Badame Refrig/ACC · February 20, 2007, 01:35:09 PM

Quote from: H3Jim on February 20, 2007, 01:19:36 PM
Nick, I think that one comes with a 1500 watt heater. Len needs something much heavier as that 1500 watts won't make dent in heating anything else but domestic hot water.

Yes Jim,
Len said he can replace the element with a higher rated one.
Nick-

Len Silva · February 20, 2007, 01:46:58 PM

I already have the heat exchanger for making hot water from the Webasto. I'm talking about putting a water heater in the coolant loop to supplement the diesel heater. It would be a relatively inexpensive mod, just looking for any negatives.

The next question is where to put it. I would think just ahead of the Webasto return but I'm not sure.

With a 4000 watt element, a 50 amp service would still have plenty of capacity for the rest of the coach. Even at 110/30 amp you could pull 2000 watts. It should save some fuel.

Len

Don4107 · February 20, 2007, 03:26:37 PM

If you put a 220V element in it I don't think you will get much heat at 110V unless you use two 110V elements in series for 220V and in parallel for 110V. Wiring would be complex. Forget once and you buy new element(s). Don't know if there is a small tank made with two element holes.

Keep us posted.

Len Silva · February 20, 2007, 03:38:24 PM

Quote from: Don4107 on February 20, 2007, 03:26:37 PM
If you put a 220V element in it I don't think you will get much heat at 110V unless you use two 110V elements in series for 220V and in parallel for 110V. Wiring would be complex. Forget once and you buy new element(s). Don't know if there is a small tank made with two element holes.

Keep us posted.

Don,

Some years ago a neighbor was complaining about slow recovery of his water heater. I checked it out and found it had been wired for 110 (it was a 220 unit) It didn't work well but served a family of five for years before we found the problem.

Len

Kristinsgrandpa · February 20, 2007, 05:00:25 PM

If you get a heater from HD/Lowes check the diameter of the heater since the larger the wattage, the longer the element.

It may not matter but some of the smaller heaters are not very big around, thus a large (longer) element might not go.

Otherwise it sounds like a great idea to me.

Ed

mikeH8H-649 · February 20, 2007, 05:45:02 PM

Len I have a 110 water heater and also an exchanger with my proheat,the setup works great,I just plumbed the exchanger into the line before the electric hot water heater,a few valves and the 110 can be isolated or open the valves and use the 110 and the water still flows through the heat exchanger Mike

pvcces · February 20, 2007, 10:20:09 PM

Two things; a 240 heater powered by 120 will only produce 1/4 of the heat that it is rated for. A 4,000 watt heater would produce only 3,413 BTU, about 1/10 of what you might want for freezing temperatures. I imagine that it would work fine at 50 degrees.

The other thing is if you put a high powered heating element into a small tank, you will likely be able to hear a rumbling sound from the heater caused by local boiling on the element.

Perhaps this info will help.

Tom Caffrey

Stan · February 21, 2007, 05:23:48 AM

Tom: Please explain this. quote " a 240 heater powered by 120 will only produce 1/4 of the heat that it is rated for." unquote

Len Silva · February 21, 2007, 05:42:49 AM

I had forgotten some very basic Ohms Law. P=I²*R or P=E²/R.
So half the voltage times half the current is one quarter the power.

Still, even 3400 btu when it doesn't cost any more might be worth the trouble.

Len

David Anderson · February 21, 2007, 06:42:31 PM

Len,

Are you trying to heat the coach with this or just domestic water? I have a 1500w Seaward in my Webasto loop which looks just like the Atwood pictured in an earlier thread. (probably the same mfg). Anyway, I've tried to preheat my engine with this and barely got a 30 degree rise in 8 hours. That is nothing. It just won't do it much less heat the coach. It does a great job at heating domestic water, however.

I do have four 1000 watt toe kick heaters that work well. We used them constantly back at Christmas when the Webasto failed at Breckenridge ski area. They worked pretty good, but used lot's of Tiger Run Resort electricity.

David

Nick Badame Refrig/ACC · February 21, 2007, 06:56:41 PM

Len,

You might be trying to reinvent the wheel here. AquaHot has the electric element option for their higher end system.

It might be of bennifit to you to give Vehicle systems a call to see if their electric option is available for purchace.

it may very well be a cylinder/exchanger with an element hook up.

And you are right that the efficency doesn't matter when plugged into park power. If anything, you created redundency...

Good Luck-

Nick-