Buderus GB142 UBA question

GW

I am having a slow week so i am building a parts list in my google Drive- it's nice to see my lists on my phone while in the trenches.



On the Buderus, I didn't know there were two UBAs until just now, what is the difference? i see one is a bit less 4 than the other.



Thanks for any help.



For all you guys that rule with these boilers- you stock a blower? Anyone actually carry a uba with them in the truck? Please share what parts you carry if you can. We have a couple dozen out there that we have installed and others that we haven't installed.



Thanks, gary