On Demand Heaters? Lets get some opinons

[JoeA]

Ok. Evederything in my bus, from electricity to plumbing to gaslines has been fully researched and profesionally consulted etc. (my photo Album "aimless Pursuits" Is a little behind the current stage.

My question to all-Y'all. On demand heaters. I know they make kind that are shaped like an AC window unit, that are made for RV's but they are expensive. The smaller Propane units by Paloma and Bosch are perfect. Except none are approved for use in RV's. Are there any bussers out there with experience using these??
I have a Bosch 38B model which is 25" x10"x 7" roughly. The Mounting requirements are simple. The Propane and water req. are easy to meet. The 4" (O.D.) double wall class B vent pipe with a 6' minimum vent heighth is easy enough to obtain out the rooff of my bus. It is my belief that I have plenty of venting available to create sufficient draft and the instructions explain about opening or turning on all other air using appliances and running the water heater wide open for a bit while holding a mirror next to the Vent pipe to see if the mirror fogs with dangerous combustion gases. All this I understand. Also there is the issue of freezing the water that is in the heater which will kill it. Which can happen in two types of cases. 1) the Bus is not heated and there is water in the heater and it is cold enough to get freezing temps inside. My solution is draining the thing during serious cold temps especially if I am going to be away for some time etc. 2) the issue is improper venting causing cold air to draft down and freeze the water lines. Again I am prepared to discontinue use during much of the freezing season.
Also, all my water storage and lines are interior, so Water temp rise shouldn't be an issue with performance for a basic shower. (1.3 g/min with a 50 degree Temp rise)
Lastly, the places that sell these small units advertise them as use for mobile washing applications and RV or cottage. Not all say RV but some do. Backwoods Solar an Alt. energy company sells them and says they are OK for RV's. Of course I undrstand that Bosch's Literature is a liability thing and will void warranty. Mostly what I am wanting is experience info. If this is something you have to not mention you have to get full coverage insurance on your rig through GMAC Goodsam or Camping world etc..
For those of you that know About 'Phred's Poopsheets' , he discusses having used them and the do's and don't's and safety concerns.
any help on such a long message would be great
Thanks
JoeA [/b]

[firedancer]

We had excellent experience with the RV-500, made by Precision Temp. Our installation is detailed on Michael's Mobile Homestead website at

http://www.mobilehomestead.com/buses2/david/david1.htm

The unit is relatively small and can be installed using less space, being directly vented to the outside. I believe Michael just installed one in his new bus conversion.

Though the unit it pricey, it works well when you're trying to maximize the use of available space. I have a 40-gallon freshwater tank inside the bus and so it very easily heats the water.

[soused moose]

Nope …didn’t install an on-demand water heater in our bus.
Went for a typical Atwood 10- gallon RV one instead.
But I do have the RV-500 water heater sitting right next to my computer in a pile with a bunch of other stuff we’ll install in our trailer..

They’re very expensive units costing approx. $879.00 plus shipping …but I wont know if they’re worth that amount till we use it awhile.

I went back and forth on whether I should install a Paloma or AquaStar instead ,. And only went for the RV-500 because they can be installed down low somewhere .
If I felt I had the wall space to hang a Aquastar I would have bought one of those units.
Because the company has a great reputation and the units are used everywhere..

On the other hand ,The RV-500 is sold by only one dealer on the whole freakin’ planet …which could mean they’re exceptionally well-made or it could be they’re just an expensive cool looking piece of junk that nobody else wants to carry.
One thing I am a bit concerned about with this heater is the repair and parts issue.
I’m stuck with getting parts from only one place…but if I had picked up an Aquastar , I could have found parts and people to repair the unit just about everywhere in America.

[Jerry Campbell]

I've lived with them in an rv and blown them up and melted my faucet when the temp and pressure sensors failed. The way they work is by slowing down the flow thereby increasing the temp of the water as it passes by. Also decreasing the pressure which is a drag in an rv with a little on demand pump. And there's no way to store hot water. This time I will have a 10 gal propane/electric with a heat exchanger. And heat water with engine, heat stove, solar or propane.
Good Luck
Jerry

[Jerry Campbell]

I've lived with them in an rv and blown them up and melted my faucet when the temp and pressure sensors failed. The way they work is by slowing down the flow thereby increasing the temp of the water as it passes by. Also decreasing the pressure which is a drag in an rv with a little on demand pump. And there's no way to store hot water. This time I will have a 10 gal propane/electric with a heat exchanger. And heat water with engine, heat stove, solar or propane.
Good Luck
Jerry

[JoeA]

I've had experience with aquastars before as a feed room source of hot water and it has worked awesome for years if you keep the water screen filter cleaned 1 -2 times per year.

Just never in an RV

Thanks for both your thoughts on the issue. It is very helpful.

[DizzyIzzy]

I want to install a tankless heater. I have found some as cheap as $170 on ebay. I want to save space and have hot water.n I have never hooked one up yet but the house I am living in has one and damn the water can be scolding.