A.O.Smith/Rinnai R98LSi-N ASME

[Jeremy Keehn]

I'm looking for a tankless gas indoor water heater for my 4 bedroom house and I came across this A.O.Smith/Rinnai R98LSi-N ASME. It seems like a really good deal, I'm wondering why, and I have a few questions:

Why isn't the brand simply 'Rinnai'? Is this a hybrid brand and I should be concerned for some reason?
This looks almost identical to the R98LSING, but it's a different model #. Any major differences?

I want to buy this thing, so any non obvious advice or help would be appreciated.

Thanks

Specifications

- Make: A.O. Smith
- Manufacturer: Rinnai
- Model: AEU-VA3237FFUA-N (R98LSi-N ASME)
- ASME Approved: Yes

[Dana]

It looks like an A.O. Smith branded Rinnai commercial hot water heater, not an A.O. Smith design.

ASME rated tankless heaters are usually suitable for space heating & combi-heater as well as commercial hot water service, but usually have much lower turn-down ratios, but according to the spec it's min-fire goes down to 19,000BTU/hr which isn't terrible. (Many residential tankless units can run down to about half that though.) It's max-fire of 237,000BTU/hr is higher than the 199K residential tankless limit, but not so much so as to create a problem in a residential app.

This is also not a condensing unit- the raw combustion efficiency on it is about 85%, which would require stainless steel Z-vent rather than PVC for the exhaust, which adds quite a bit to the installation cost. Sometimes it's cheaper to go with a condensing heater and PVC venting when the venting runs have any substantial length, avoiding the high material cost of the stainless.