On demand Water Heaters. Some Opinions/knowledgePlease.

[JoeA-SKO]

Ok. Everything 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 :shock:

 

[fmtaylor]

tankless water heater for RV use.

I am planning to use the Precision Temp RV-500 tankless water heater. Sure it costs about $900 , but it is approved for RV use and mounts in a standard size water heater hole.

 

[Eric von Kleist]

This is neither opinion or knowledge, just something I kind of recall...

(reposted from the other thread on this topic-sortof)

I looked into the tankless heaters at one point (before I saw the price tag). IIRC, they raise the water temperature so many degrees (varies by model and manufacturer) above ambient. That is, if your incoming water is 60 degrees, and they raise it 50 degrees, you'll get unlimited 110 degree water. I could be dismembering it wrong, though. Or it could be degrees C instead of degrees F that they were quoting.

 

[SeanF-SKO]

There are some that raise the temp of the water a fixed amount, so it will be X degrees above its (incoming, cold) temp. The Bosch/Aquastar 125B models do this (see exception below).

Others heat the water to a fixed setting, via a temp sensor at the cold water input and the hot water output-- the RV-500 and Bosch/Aquastar 125BS ("solar") do this.

Sean