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7-yr M175

(3)

I bought a Maxim 175 (used) in 2018 and burn pellets. As an Electrical Engineer I expected an unknown number of issues described by the blogs on several sites. In hindsight new M175s had several design and manufacturing deficiencies all solvable. One by one I’ve worked through them (intermittent power, false float, failed igniter, false flame out, false back burn) and found improvements or workarounds. 7 yrs in the aerator began falling off the auger. After carefully observing several cycles and thinking about the design the fundamental problem appeared – The aerator does not actually “lock” onto the auger shaft. Yes there is a key and a slot and a 1/4″ turn to properly set it into position but fundamentally it does not “lock” in the sense of one way “latch” onto the shaft. The word lock can be used but it doesn’t actually “lock” in the true sense of the word. The conditions must be just right for it to fall off – It must have just a slightly loose fit; The hopper must go empty; The auger must go empty; The fit of the auger to its steel cylinder must be just off/worn enough in terms of fitment so as to cause the auger to jitter (resonate) as it rubs it’s empty cylinder. The auger must continue to rotate some minutes or hours after it goes empty. It seems to only occur with an empty auger. Therefore nothing is jammed or stuck… Dry pellets don’t jam or stop the auger. An empty auger doesn’t jam or stop. The aerator instead has nothing to push and no new pellets arriving to its turned-key-setting. Rotation plus resonance plus metal contracting as it cools off helps it to incrementally jitter-reverse-1/4 turn from its set position and work its way off. The angle of the bore-auger-aerator is tilted slightly downward so naturally it will want to fall off. In my case this only began to happen after I cleaned the unit really well (at fall start up) including the end of the auger shaft and bore of the aerator. Afterward the dry auger when turning started squeaking or squealing every turn-ish and it is actually jittering/resonating in its otherwise relatively loose fitment causing the aerator to vibrate just a little ~ every full rotation. The fundamental issue is no actual “lock” or “latch” in the design. it relies on there being no jitter, no resonance. It makes complete sense how a new auger or new transmission or new fitment of auger to bore or removing bridging conditions of pellets in the hopper or use of corn vs pellets all can make a difference and appear to correct the failure only to have it re-appear in future time. As a pellet fueled boiler it works. With patience and problem solving (as they occur) it’s reliability improves.

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Biggest mistake I ever made was buying the Maxim M175. May be an outstanding product in areas where the temp rarely drops below the single digits, but here in VT, where the homes tend to be older, not a good product. Struggles to maintain water temps. No guidance provided on hos to adjust the Firestar electronic control “computer.” Have gone through augers, aerators, fire boxes and have had many back burns. Customer support from Central Boiler started out great, but when the problems encountered were different from those they experienced at their engineering department the help ceased. I burn 20 ton of pellets per year with this beast!

This is one of the best pellet burner that I have seen, I have looked at a lot of them but this one beats them all for cleaning and for how long you can wait to clean them out. they don’t even leave any smoke my neighor never know I had one, had it for 5 month when a neighbor stop in to talk when I was cleaning it out he said he seen it but though that I wasn’t useing it cause it never smoked
David Bauer