A.O.Smith/Rinnai R98LSi-N ASME

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

Click to expand...

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.