Navien vs. rinnai for efficiency

[howie333]

It seems the Navien tankless unit NR210(a) is rated @max. 180,000btu / 75 deg [email protected]. Not sure why the Rinnai RL94i has basically the same performance specs, but uses 199000 btu,s ! Still on fence about purchase. Water conditioner output 3.75gpm, 2.5 bths,85+gal jacuzzi, but use one appliance at a time. only two people/No DW. I've considered the Navien NR240(a) or the rinnai RU98i for higher gpm flow, but not sure if I really need a condensing unit.

Any help;
HR...

 

[Beni]

The Navien unit is of course a bit more efficient and will use a little less gas a month. Probably in the range of $5 a month savings over the Rinnai. 4.5 GPM will be fine for two people.. Could probably get by with 3.5 GPM though the tub would take longer to fill then.

 

[howie333]

The Navien unit is of course a bit more efficient and will use a little less gas a month. Probably in the range of $5 a month savings over the Rinnai. 4.5 GPM will be fine for two people.. Could probably get by with 3.5 GPM though the tub would take longer to fill then.

Thanks for reply; local plumbers push for largest unit (Navien NP240(a) cause of incoming watertemp could change; but if spec's are accurate, i cant see why I'de need more than the NP 210(a) 180000btu unit; unless more water pressure is available after the water conditioner , but, not possible. Is there any benefit to use a unit that's oversized ? Also; not sure if I'de really need the (a) model w/ the internal circulator, esp. if efficiency is reduced operating on propane

HR...

 

[Beni]

Hum, Well Me I would use the P210 unit you indicated as that will be fine for 2 people. Water temperature does not change that much from winter to summer and even with cold water the P210 will be fine for two people.

I would not oversize a instant water heater myself. One thing, the Navien is a condensing heater (thats good as it saves energy/ money) so it needs a location to drain the somewhat acidic condensate, Outside or floor drain.

The Rinnai unit is a standard efficiency unit. Both will do the job, though from an engineering standpoint the Navien is better.

 

[howie333]

Hum, Well Me I would use the P210 unit you indicated as that will be fine for 2 people. Water temperature does not change that much from winter to summer and even with cold water the P210 will be fine for two people.

I would not oversize a instant water heater myself. One thing, the Navien is a condensing heater (thats good as it saves energy/ money) so it needs a location to drain the somewhat acidic condensate, Outside or floor drain.

The Rinnai unit is a standard efficiency unit. Both will do the job, though from an engineering standpoint the Navien is better.

Thanks for reply.
That's kind of what I thought. I've considered the "A" model's internal pump in case the heated water takes too long, but Navien confirmed hot water availability should be the same as my tank type is now. The differences between the 210 and the 240 are only about .5 gpm.@199,000btu's. Since the 240 produces more BTU's,if not used, is it being wasted or just available if needed? Drain is no problem

HR...