Rinnai propane water heaters

[OldHilux]

Rinnai states on their website that their tankless water heaters are not for use in an RV. I cannot figure out why. Is it because of CO leaks in the exhaust? Surely that would be unacceptable in a residential unit as well. Is it because they use up room oxygen? If that is true, why don't the direct vent models work for RV usage?

I am stumped. I hate hearing rules without any reason given for them, maybe someone who knows more can chime in?

Alternatively, did anyone here try to use one of these in an RV? What went wrong?

 

[Rene T]

I have one in my house. The exhaust pipe is white pvc and if I remember right, it’s a pipe within a pipe. The combustion air is drawn in through the big pipe and the exhaust goes out the inner small pipe. The outside pipe never gets even warm.
Maybe it’s because the pressure regulator is not big enough to supply the needed propane. The regulator I have is about 6” diameter and takes care of my clothes dryer, gas cooking stove and the Rinnai.

 

[TonyL]

I think you will find that they are more concerned about vibration whilst the RV is moving. If your RV is static, see if they recommend them for park/residential park homes. Whilst they are running, they do require quite a high throughput of propane, but well within what an RV regulator should cope with. My question would be, why a Rinnai? We have them here, and I have to say that within the industry, they are not well liked.

 

[OldHilux]

Mostly because I like their wall furnaces. I don't know the gas tankless water heater market well though. What brands would you suggest instead?

 

[Rob&Deryl]

Maybe they require 120v and would not be suitable in a 12v only application?

 

[OldHilux]

Don't most RVs have 120v though?

 

[Larry N.]

Don't most RVs have 120v though?

Only when plugged in or when the generator is running, for a great many RVs, though a number of rigs have inverters that, with enough battery capacity, could work for this.

 

[TonyL]

I don't know if the make is available in the US, but Ariston do make a water heater, and as they make domestic boilers as well there is a decent backup service.