New Tankless Questions (likely Navien)

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Gareth Collins

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New York
I have an old Noritz N-0751M installed which appears to have given up the I am in the market for a new tankless water heater.

While it worked for 14 years, it wasn't really done right. It was installed only a few weeks after we moved into a new house and I didn't know what I was doing (the previous boiler from WW2 died as soon as we moved in).

It had a few problems. It was missing the isolation valves to properly allow it to be flushed, it is connected directly to the basement wall instead of to a plywood(?) backing, it gave out an awful sound periodically when you turned it on, it had a flexible gas pipe which apparently isn't code in my town. All these things I found out much later.

This time I want it by the book. I know the new condensing Naviens are set up with dual openings so that fresh air can be sourced from outside. A couple of people I have asked to take a look have said "oh, you don't need that"...which I feel is wrong. Am I right to insist or am I just being too picky? This is in a laundry room in a finished basement.

If I do get the air from outside, any issues with using a concentric vent which can use the existing hole vs. a completely separate hole for the intake?

On a completely separate question - when getting quotes, it seems pretty random whether the Navien A series or S series will be used (sometimes that is not even clear which one I may get). My understanding is the difference between the A and the S is the recirculation infrastructure. If I don't decide to setup an external recirculation loop, is it still worth it to get the A just for the internal recirculation? I understand that helps if you have people in the household which will turn the hot on and off and on and off? Is my understanding correct?

Just wanting to make sure I don't screw it up again.


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Peace valley missouri
Use of a concentric vent will take a larger hole or can have two separate holes. Why pull heated/ cooled air from inside your house pulling a negative pressure sucking air from outside.
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