"WWSD On Diff" - How it Works - Navien NCB 240-110H

[Calibretto]

I recently had the Navien NCB 240-110H installed in my home and I'm trying to decide on the appropriate setting for "WWSD On Diff". The only info in the manual on this setting is on p. 107: "Set the differential temperature to deactivate the Warm Weather Shutdown."

Link to the manual PDF: https://www.navieninc.com/downloads/ncb-h-installation-and-operation-manual-en

When I go to this setting on the boiler itself, it gives the following description: "the boiler will reactivate when the outdoor temperature differential falls below this setting".

I currently have the "WWSD Temp" set to 55f and the "WWSD On Diff" set to 15f. I have the following possible theories on what this will mean and I'm hoping someone can tell me whether one of them is right, or explain how it works if I'm totally misunderstanding:

1. When the outdoor temp hits 55, the boiler will shutdown and remain shutdown until the outdoor temp hits 30, at which time it will turn back on and remain on until the outdoor temp hits 55 again.

2. When the outdoor temp hits 55, the boiler will shutdown and remain shutdown until the outdoor temp hits 15, at which time it will turn back on and remain on until the outdoor temp hits 55 again.

3. Neither the above are right and I am way off track.

Any advice is appreciated. I am just a homeowner and totally new to boilers.

 

[Fitter30]

Boiler side isn't going to run unless room thermostat is calling for heat. Diff setting can be as low as 5° f. Just don 't want the setting low enought that it short cycles everytime a cloud shades the house drops the outside temp brings boiler back on then cloud moves on outside temp rises and shuts it off. 55° don't u still need heat till at least 65°- 70° if its windy? Might consider outdoor reset it varies boiler water temp on outside temp.