Mostly because without them, the boiler clean-out door is very close to the floor, perhaps even restricted. The very same for EFM bases, too.
I do the same for AA and AHS, but some folks set them flat on the floor....not good if you have moisture all the time.
Those bases won't last more than 30 years in those situations, AND will not be rebuildable.
Yes, I'm aware of the height issue filling the hopper if you are vertically challenged, or one of the old farts like me.(That is why they make augers...a no-brainer when the funds are available.)
Patio blocks will give you 2" if that is more favorable.
Also, leave plenty of room to access the rear stack, AND make it easy on yourself to clean and/or remove the stack for cleaning. An easy tip: When assembling the stack, it is easy to apply a liberal amount of anti-seize paste to the joints before you place at least 3 metal screws in each joint. If you don't do it then, you never will. The piping will disassemble as easily as if it were brand new. Otherwise let the banging and smashing begin!!!!!!
ALWAYS anti-seize the door hinges, latches.....any bolt you can see. The three bolts that hold the burn grates are something to become familiar with also. Easy project to remove and clean if you can remove them in a minute of less.....Also, please do yourself a favor and locate the air scoop and expansion tank somewhere OTHER than directly above the boiler, where sometime down the road, the vent will corrode up, druzzle some nasty water on to the top of your immaculate covers and leave you extremely PO-ed at you lack of thought about this VERY common issue. I see it daily, and only wonder why the previous plumber couldn't just move it away......monkey see, monkey do!
*****These few paragraphs are priceless advice. I would add never-seizing the tankless bolts/studs if equipped.
Luckily I noticed it right away and cleaned it up.........also put a bunch of rags down. I've got a new one and will install it before I fire up for the season.
