Hot Water Replacement

On demand maybe if you're always plugged in to shore power. Otherwise, doesn't seem like the best choice for a mobile RV.

I have been an RV tech for 43 years. I would NEVER have a LP powered On Demand Water heater. The On Demands are too finicky and rarely give the higher temps that a lot of people want and like. I have over the years replaced On Demand Water Heaters under warranty with regular water heaters because the customer demanded it and the OEM's agreed to pay for replacement. I have also replaced for Customer pay when out of warranty. Doug

Since Grand Design started putting OD water heaters in some of their units (the Solitudes and Momentum fifth wheels still have 12-gallon standard WHs), there have been many, many posts about problems with them over on the (older) GD forum. There are the problems that dougrainer mentioned plus: 1) without the option to use electric, they go through propane rapidly, and 2) the Furrion units are not insulated and are notorious for freezing and cracking the coils when the outside temps drop or the units are not properly winterized. I would never install one.

Rob

Had a propane one on our boat years ago. We would use 3-4 gallons getting the temp to settle in...then any slight adjustment and you got scalded or iced.

Electric has the problem of providing enough power. A 30amp outlet can provide 2880w continuously (limited to 80% of rating) but that's for everything in the RV. 1200-1500w won't get 40F water up to 110-120F at any reasonable flow rate.

I’ve never understood how a small OD wh can provide adequately (subjective I know) hot water for a high flow requirements of a shower, especially during the colder months.

On demand is a bad idea for RV use. Stick with a tank LP/ electric heater

I have an on demand. You waste too much water waiting for the hot water to come and get surges of cold water.

I've had a Truma od water heater in my 2018 rv for four years and have had zero problems with it and plenty of continuous very hot water. Certainly hot enough to be super uncomfortable and maybe cause an injury. Dunno about others but am I just lucky?

ernie1 wrote:
I've had a Truma od water heater in my 2018 rv for four years and have had zero problems with it and plenty of continuous very hot water. Certainly hot enough to be super uncomfortable and maybe cause an injury. Dunno about others but am I just lucky?

A lot has to do with the starting water temp, how fast the water is flowing and how many BTUs of heat energy the burner can supply.

In temperate places you might start out with water temps above say 80F+ and at those temps takes no time and not all that much heat energy to raise the temp to say 120F at only 1 or 2 GPM..

Now in colder climates you might be starting with water temps of say 50F and now it takes a lot of heat energy to raise to the same 120F and to get there you might have to have the water at .5GPM which may or may not trigger the burner on or may result in burner on/off/on/off cycles..

ODs do have an hidden enemy, dissolved minerals in the water, the high temps of the flame causes the minerals to fall out of the water and were they fall is in the tubes of the unit which eventually leads to mineral clogs if you do not do periodic de mineral maintenance. Untreated well water tends to have much higher mineral content than say highly processed city water.. Therefore, city water is preferred for ODs but even then some maintenance should be done on a regular basis..

I was going to replace my sticks and bricks tank water heater once after having multiple tank failures.. Discussed the idea of switching the house to a OD with a plumber.. Even the plumber told me that I was better off sticking with a tank water heater.. And no, I was not buying from or needing the plumber, was trying to get the scoop before committing a huge chunk of money on a project that was destined to fail..

My water is supplied by my own well, has an extreme high mineral content and that is after a large water softener.. The water temp out of the well is 50F yr round.. Would have to replumb 20ft of gas line to 3/4" in order to supply enough BTUs in gas to the water heater.. Three strikes..

ernie1 wrote:
I've had a Truma od water heater in my 2018 rv for four years and have had zero problems with it and plenty of continuous very hot water. Certainly hot enough to be super uncomfortable and maybe cause an injury. Dunno about others but am I just lucky?

Truma is a higher line of On Demand(Germany) and has a better track record. Truma replacement would require running the control communication cable to a spot inside for the wall mount control. Truma's also require once a year decalcification, kind of a pain to do, just time consuming, not hard. Doug