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Author Topic: Electric Instant Hot Water Heater  (Read 3547 times)
HB of CJ
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« on: January 09, 2008, 04:18:20 PM »

Would an electric instant hot water heater be practical for a coach installation?  Dunno.  Would it kinda be like a microwave oven?---using lots of energy but only being employeed for short periods of time?  Would like to have about 3 gallons per minute minimum at around 110 degrees F. at the shower head.  110 or 220 VAC 60 htz?  Would this be practical?  Thanks in advance.  Smiley Smiley Smiley
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Stan
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« Reply #1 on: January 09, 2008, 06:29:28 PM »

I didn't look up any specs but I have used several 1 gpm tankless water heaters. They drew 40 amps at 240 volts so do your own math.
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Kristinsgrandpa
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« Reply #2 on: January 09, 2008, 06:49:14 PM »

I looked at one at Lowes (Tiny Titan I think), I was impressed with size,cost etc.

I wanted one till I asked the salesman how much the repacement elements were and he said "I don't know, we don't stock them". 

I'd hate to be without hot water for a week while Titan shipped one.

Ed
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Will & Wife
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« Reply #3 on: January 09, 2008, 06:51:51 PM »

I've been considering LP instant hot water, but still haven't figured out how I'm going to vent the thing. After doing a little research, I've come to the conclusion that you need at least a 3 inch exhaust with either a slight downward run or an upward run with some type of elbow or means for draining off the water generated from burning propane. If electric is the way to go, I'm not convinced because to the tremendous draw. I'd have to fire up the jenny just to take a shower or do dishes Cry
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makemineatwostroke
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« Reply #4 on: January 09, 2008, 06:57:57 PM »

HB go to this site and read the amp draw  www.etankless.com
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Merlin-PV
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« Reply #5 on: January 09, 2008, 09:07:25 PM »

I have 3 instant 110v installed within 6"  of the shower and sink outlets. 30 amp draw 1/2 gal per min.seems to be enough more would just drain your batterys and water tank. can stay out 2 weeks before dumping tanks and water refill 800 watts solar on roof still need to generate aprox 2 hrs a day to keep up (total electric coach) works for me!
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Lee Bradley
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« Reply #6 on: January 10, 2008, 08:35:08 AM »

I've been considering LP instant hot water, but still haven't figured out how I'm going to vent the thing. After doing a little research, I've come to the conclusion that you need at least a 3 inch exhaust with either a slight downward run or an upward run with some type of elbow or means for draining off the water generated from burning propane. If electric is the way to go, I'm not convinced because to the tremendous draw. I'd have to fire up the jenny just to take a shower or do dishes Cry


Have you looked at the RV500?
http://www.houseneeds.com/shop/HeatingProducts/WaterHeating/rv/rv500waterheatermainpage.htm
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Lee Bradley
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« Reply #7 on: January 10, 2008, 08:40:40 AM »

Here is a pretty good collection of tankless water heaters electric, gas and oil. The electrics look be pretty big current draws unless you want a single sink model.

http://www.houseneeds.com/shop/HeatingProducts/WaterHeating/products-water-heaters-sortelectric.asp
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HB of CJ
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« Reply #8 on: January 10, 2008, 01:54:38 PM »

Thank you everyone.  Now wondering if a 4000 watt sine wave invertor would be happy with an 110 VAC electric instant hot water heater pulling about 3500 watts?  Stacked invertors for 220 VAC?  What about a 3000 watt 110 VAC invertor?  Overload mode?  Service life?  Load sharing/shedding would be necessary.  If doable, the heater would be mounted very close to the shower head.  Finally, what gpm/psi/temperature is needed for a good shower?  Special shower head?  Looks like an electric heater is a real watt hogg.  Smiley Smiley Smiley
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PP
Will & Wife
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« Reply #9 on: January 10, 2008, 06:18:13 PM »

Lee, I just checked out the URLs you listed. I downloaded the installation manual on the RV500 and will spend this weekend (Supposed to be dry for a change) crawling around in my rear bay seeing if I can make it work. I'm also checking out the Titan that was mentioned earlier, even though it is electric. I'm curious if maybe one of those less expensive inverters that kick out 5 or 6KW might be pure enough for a tankless heater. I could go with 2 electrics (1inKit & 1inbath) plus another inverter for the same price as the RV500. Decisions, decisions. Thanks Lee, Will
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bruceknee
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« Reply #10 on: January 11, 2008, 04:35:12 AM »

There are a half dozen busses  here in Delaware that are using proheats for domestic hot water, instant, endless, inexpensive and you can also heat your bus and or engine. It is an easy installation, and affordable.
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Rick Brown
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« Reply #11 on: January 11, 2008, 07:55:28 AM »

I've got an RV500 propane fired tankless heater in my 4905.  I cut a 18" (+/-) square hole in the side of the bus for mounting.  Built the shower so the HWH fits below a seat/shelf in the shower.  Vents by default to the outside.  Folks at PrecisionTemp are helpful and easy to work with.  Product somewhat pricey (I recall $600 or so).
RickBrown in Reno, NV
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Lee Bradley
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« Reply #12 on: January 11, 2008, 08:10:24 AM »

Rick,
Sounds like a very nice installation. Are you happy with how it works? Do you have a cold water purge?

Thanks,
Lee
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Rick Brown
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« Reply #13 on: January 11, 2008, 01:38:50 PM »

Yes, I'm happy with it.  Provides enough hot water that some cold must be blended in for a shower.  I'm not sure what you mean by a cold water purge.  You need to be diligent about keeping it from freezing (just leave it on if you are unsure) because it looks like a very expensive fix if it freezes.
-Rick
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Lee Bradley
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« Reply #14 on: January 11, 2008, 03:55:10 PM »

By cold water purge, I meant a system to purge the cold water in the hot water pipes back to the supply tank so you have hot water as soon as you turn on the hot tap.
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Christyhicks
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« Reply #15 on: January 11, 2008, 04:59:58 PM »

This subject has come up several times in the past. . .so you might do a search for tankless water heater on this site to read some of the older posts. 

I've mentioned in the past (hate to keep repeating my old boring posts), about some small, tankless, non-vented propane units available on Ebay.  I put an Excel in my office, where we mostly wash hands and maybe coffee cups and occasionally a bath for the grandbaby, and we've checked it with out combustion analyzer to find that it really doesn't put out measurable carbon monoxide.  I have a c/o detector mounted on the same wall, about 8' away from the unit and no matter how long it's run, the c/o detector has never sounded.

I recently ordered one for BigBus, but of course, it'll be awhile before I can testify to whether it will work as well as I think it will.  I think I paid about $255 or so for it, so it was a pretty good price.  The first one I bought was about 1/2 that, but I guess they're selling good enough that the minimums are higher now. 

The precision temp is nice, we just didn't want a big hole/grill on the side of the bus if we could help it. . it's bad enough the a/c units have to have big grills, ha ha.  Christy Hicks
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Will & Wife
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« Reply #16 on: January 11, 2008, 08:48:57 PM »

If it wasn't for having to cut a big hole in the side of the bus, I would definitely go with the RV500. But I'm giving the electric set up a whole lot more consideration for just that reason. It almost seems sacriligious to cut out all that stainless. Just not sure I have the heart to do it. The installation manual is calling for an opening in the neighborhood of 18 X18. I have a squirrel cage set up through the floor of the generator compartment so I don't have a vent grill in the bay door. It comes on when the jenny runs and works great.
Even my two LP furnaces are vented through the floor instead of the side wall. What can I say?
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Rick Brown
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« Reply #17 on: January 12, 2008, 08:30:35 AM »

No purge.  My water lines are too short to make it worth while.  Usually I just 'purge' into the dog's water dish or something similar.
-Rick
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