Another "once you've had one" and another one who does not do a yearly maintenance. We are half timers and our single electric element is all we need 90+% of the time so no need to change the nozzle every year or even three. Have not used the diesel boiler more than a few times in the last two years so why would I change the nozzle every year? With a lot of use the hole in the nozzle actually gets too big and starts putting too much fuel into the burner = smoke and smell.
It's nice to have enough "free" hot water at the end of the day of traveling for two showers. Even if it's really cold out, it's no problem to stay warm going down the road as 400 HP puts out a lot of heat that the dash heater cannot capture, but the AH can.
We will be spending three months out West this summer boondocking often so I'll change the filter and nozzle for the second time in 10 years as it's starting to smoke some on start up. The AH is not as fragile as you are lead to believe. Probably should not brag but I've never had to rap on a check valve to get a zone to work.
as mine has been very trouble free.