Tankless hot water heater related questions

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monkey1

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I am replacing my tankless HWH soon. I have a few questions related to the new unit.
1. My municipality provides 7 CW natural gas pressure for my residential line. If I buy a tankless HWH that is rated for 8 CW, will it run?
2. How often do I REALLY need to descale the tankless HWH with white vinegar? I have a 2-person household.
3. For how long do I run the descaling process? What will happen if I run the descaling process longer?
 

Breplum

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Descaling frequency is important in relation to the mineral content of your water source.
In our municipal supply here, we say that three or so years is ok between descaling.
I have had three recent descale jobs who report the unit has never been descaled in 13 years.
For those, I use commercial Whitlam descale fluid (diluted) and run it for an hour: Oh boy, what a load of crud came out.
For a unit that is descaled on a proper yearly cycle, then 2 Gal. vinegar is great as long as the mineral content of the water was low enough. With vinegar on a regular descaling schedule, I run 1.25 hr. or longer.
CLR is said to work well also.
As to the inches water column question: Different mfrs products have different tolerances. Call mfr and ask.
Navien NPE A series says it can handle 22ft of 1/2" gas pipe if directly from the meter.
 

Dana

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As to the inches water column question: Different mfrs products have different tolerances. Call mfr and ask.
Navien NPE A series says it can handle 22ft of 1/2" gas pipe if directly from the meter.

That's true, but Navien is the extreme outlier.

I don't know what magic they're working, but Navien is clearly doing something to make it easier for the average idiot to replace a plain old gas tank water heater with a tankless Navien without having to upgrade the gas plumbing. (Good for Navien!)

But I suppose as with anything else, the more idiot-proof you make something, the more creative the idiots become...
 
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