Upgrade from Navien NR240 to NPE-240A2

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Andrew Herman

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Good morning,

Our 2008 Navien NR240A started leaking in several places. After trying to repair a couple of times we decided to update to a new NPE-240A2.

The old unit pump was set to run 24/7 and has done well for the last 13 years. In order to minimize plumbing install issues, switched to NPE-240A2. House is about 95 feet wide with a return loop running between the floors. So, I guess about 200 foot hot water loop - 1" pex.

New unit has been for a couple of days and I've noticed a difference. The hot water coming to the various faucets is not as hot as before, even though the unit is set at 125. In reading the setup books, I noticed that the new heater has settings for hot water temp drop of 9 degree before activation and I think it checks temp and turns on the pump on every 20-30 min. I understand this can be changed.

Does anyone know if the old 2008 unit was set up the same way- I think it only had dip switches.

Any thoughts would be appreicated.

Thanks,

Andrew
 

Bannerman

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In reviewing the manuals for both models, I did not find reference to a recirculation return temperature setting for the NR240-A. It appears the recirculation will be continuous within the scheduled recirculation time which is adjusted in 30-minute time segments.

The NPE-240A2 also supports continuous recirculation, but I understand the default setting is Intelegent Recirculation which will identify your hot water usage pattern history over a 1-week period so as to continue to anticipate when you will likely repeat that patterns during the subsequent weekly period. As it is basing patterns in past history, this provides little flexibility during times that do to follow the same usage patterns.

To obtain the most user flexibility while maximizing fuel savings, suggest adding the Navien Hot Button option. No recirculation will then occur until a button located in the bathroom, kitchen, laundry room or powder room is activated. Once activated, the pump will recirculate the hot water for 15-minutes or less if a remote sensor is installed at the furthest distance from the WH.

If the button is pressed when a person enters the bathroom, the pump will have advance opportunity to circulate and deliver hot water closeby to that bathroom's faucets before hot water will likely be actually needed.
 

Andrew Herman

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I've changed the circ method on the new A2 to continuous, but still see a larger temp drift at the remote faucets than I did with the old unit. According to the installer section of the new manual - the heater checks temp only every 30 min and there is an allowed 9degree drift. Can't find that info on the old Navien.
 
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