My Central Boiler Maxim M255 PE journey

thenrich

Member
Aug 11, 2014
15
Central, WI
After 13 years of owning a Central Boiler Classic 6048 we finally traded it in for the Maxim pellet/corn boiler. The 6048 did a great job of heating our 3200 sq/ft in north-central Wisconsin and has certainly paid for itself a few times over. The nice thing about those things is they burn anything and everything. Zero problems mechanically but she was a hungry beast and I was always chasing down firewood (12 - 15 full cords annually). For pellets or corn someone just delivers them and places pallets neatly in any location you'd like in about 30 min vs. weeks and weeks of harvesting, splitting and stacking. Easily worth the extra expense of pellets. Because we liked the idea of alternative fuels we decided on the pellet boiler. Our indoor gas furnace has always been our backup.

With all that stated I noted there really isn't much online about these things so I thought I start a journal of sorts. Here are some facts to add context to the journal as I make logs

  1. The first big obvious difference is the size of the M255 is less then 1/2 the size of the 6048 and only holds 90 gal of water.
  2. The boiler sits next to our exterior garage about 90ft away.
  3. Our house was built in 2006 and is modern construction. It is 2x6 construction and very well insulated. We have 3 levels.
  4. We heat the entire house, domestic water and a 28x28 external 2x6 construction insulated garage.
  5. I'm starting out with 8.4 ton of softwood pellets. I really don't know where we'll end up but that's all the extra room I had in my detached garage.

After the initial installation we started it right up with no issue. It's electric ignition. I have not alternated the standard air settings that were pre-set from the factory. I feel like that will be a learning process. I will keep the post undated with bags of fuel used, temps, problems, etc
 

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Mr._Graybeard

Feeling the Heat
Apr 27, 2012
278
Southeast Wisconsin
I've heated our old southern Wisconsin farmhouse with a Harman PB 105 pellet boiler for seven seasons. We have a hydronic heating system, so the boiler is my choice; if I had a forced air system I would have opted for a furnace like a Harman PF 100 or Fahrenheit Endurance. My boiler is in the basement and direct-vented. It radiates heat that I would have wasted if I had an outdoor boiler. My system transfers heat to my backup cast-iron oil boiler, but since the burn is 100% controlled, I have never seen a need for any kind of storage.

Last winter we burned about 5 tons of pellets. We're usually in the 5-6 ton range. The house is 100-plus years old and poorly insulated in spots.
 

Former Farmer

Feeling the Heat
Apr 12, 2008
485
NE Wisconsin
Did they recommend thermal storage?
I think that with a pellet boiler, storage is not a concern. The boiler can modulate to whatever feed rate is required for the set temperature. With a firewood boiler, I think the storage was to be able to burn the wood efficiently and store the extra heat generated. I don't know if a pellet boiler running at 50% capacity is that much less efficient than running at 100%.

I know that talking with "Sting" on the old Iburncorn forum, he highly recommended leaving the energy in the pellets rather than losing some energy in storage.
 

thenrich

Member
Aug 11, 2014
15
Central, WI
I seem to be going through 1.25 - 1.5 bags a day. Temp has been between 25 - 45 degrees. Very little ash or smoke. It smokes a little between cycles.

I also found Superior pellets at Fleet Farm for $3.99 I mixed the fuel in the hopper 1:1 and really haven't noticed a difference yet. Superior is a hardwood and is a darker pellet.
 
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Mr._Graybeard

Feeling the Heat
Apr 27, 2012
278
Southeast Wisconsin
I'm probably burning a bag a day at this point with temps in the 30s-40s. I burn Superior/ Marth pellets all the time, in fact I just picked up a ton for $199.50 at Fleet Farm. I do prefer Menards because they keep the pellets under cover.
 

thenrich

Member
Aug 11, 2014
15
Central, WI
I'm probably burning a bag a day at this point with temps in the 30s-40s. I burn Superior/ Marth pellets all the time, in fact I just picked up a ton for $199.50 at Fleet Farm. I do prefer Menards because they keep the pellets under cover.
haha....I actually just did the same at Menards and I'll just mix as I go.

I did try some Marth as it was a local gas station. I think it was like $5.50 a bag? Really dark pellets.
 

thenrich

Member
Aug 11, 2014
15
Central, WI
I've heated our old southern Wisconsin farmhouse with a Harman PB 105 pellet boiler for seven seasons. We have a hydronic heating system, so the boiler is my choice; if I had a forced air system I would have opted for a furnace like a Harman PF 100 or Fahrenheit Endurance. My boiler is in the basement and direct-vented. It radiates heat that I would have wasted if I had an outdoor boiler. My system transfers heat to my backup cast-iron oil boiler, but since the burn is 100% controlled, I have never seen a need for any kind of storage.

Last winter we burned about 5 tons of pellets. We're usually in the 5-6 ton range. The house is 100-plus years old and poorly insulated in spots.
We have hydronic in our finished basement, forced-air everywhere else.
 

Mr._Graybeard

Feeling the Heat
Apr 27, 2012
278
Southeast Wisconsin
haha....I actually just did the same at Menards and I'll just mix as I go.

I did try some Marth as it was a local gas station. I think it was like $5.50 a bag? Really dark pellets.
Superior is a Marth brand. I think the pellets are all pretty much the same, at least the hardwoods are. They have also sold hardwood pellets under the Pennywise brand -- I used to see them all the time at Menards.

I wonder if you see Rib Mountain pellets in your area. They have had a great reputation, but limited distribution. They also were in some financial trouble awhile back and may no longer be in business. I don't see much recent mention of them online.

Otherwise, I like Dejno's pellets, which come as either softwoods or a hardwood/softwood blend. The blends are usually pretty competitive with hardwood brands price-wise. Indeck was big into pellet production up in Ladysmith, Wis., but I haven't seen them in the big-box stores in quite some time.

If you have a Tractor Supply in your area, they sell Ozark Hardwood pellets under a house brand. I don't recommend them -- If you think Marth pellets are dark, you should see Ozarks. They burn OK but don't produce a lot of heat. They also are very ashy.
 

thenrich

Member
Aug 11, 2014
15
Central, WI
Just a brief update: I'm getting about 7 days right out of about 400lbs (10 bags) mixed Superior (Hardwood) and Western Elite (Softwood)

I really dunno if that's good or bad but I'm sure demand will increase as it turns colder. Next week is high in the 30's and I'll be bow hunting the next 2 weeks so I should be able to keep tabs on usage.
 

Mr._Graybeard

Feeling the Heat
Apr 27, 2012
278
Southeast Wisconsin
I found a copy of the owner's manual for your heater. It looks like a bottom-feed design. It should be able to handle hardwood pellets without any worries about ash buildup -- in fact, you might want to consider blending hardwoods and corn instead of the softwoods.
 

thenrich

Member
Aug 11, 2014
15
Central, WI
I found a copy of the owner's manual for your heater. It looks like a bottom-feed design. It should be able to handle hardwood pellets without any worries about ash buildup -- in fact, you might want to consider blending hardwoods and corn instead of the softwoods.
Corn is so expensive compared to pellets right now. I might dump a bag in there just to see what happens though.
 

thenrich

Member
Aug 11, 2014
15
Central, WI
Update: Been using the boiler for over a month now. In the house and domestic water really no difference then the 6048. Few items to mention:
  1. It appears I have a leak somewhere as every day when I look under the chimney box in the back of the unit I see a small puddle of water. At first I thought it was nothing, maybe condensation. After further inspection though I've noticed I've been having to add additional water to the reservoir. I do it right from the house and takes less then a minute. Although, not hard to do, I called the dealer for an appointment. They are coming Friday. I also called CB and was able to talk to a very knowledgeable employee. He suspected back-burns in which the boiler extinguishes the burn with water from the reservoir vs something really bad like the water-jacket. So I'll update this post when I learn more. (update - 12/3/2019: It turned out there was no leak. The system just was not entirely full of water and took time through multiple cycles of pumping water through the in-floor heating)
  2. It appears Marth's brand Superior hardwood pellets suck. I normally burn the Western Elite Ponderosa Pine but have been experimenting with the cheaper Marth Pellets. To my surprise they really burn like crap. I'm left with a big pile of pellets not completely burned. They seem to be ok if I mix, and mix really will, with the softwood pellets. The softwood pellets leave a nice little pile of ash and that's it. (update - 12/3/2019: The Superior pellets indeed DO NOT suck. I had my fuel rate set too high and the air rate too low. They are good pellets and burn very well with little ash.)
  3. It's getting cold here, highs in the teens and lows in the single digits. I really haven't messed with the stock airflow settings higher or lower yet and I haven't seen where the unit struggles a lot to keep up. The only time we really saw it kick into high was on the initial startup and it was bringing the in-floor heating up to temperature.
  4. To date, the big buck I've been bow hunting has eluded me. With that said my 12 y/o got his first with a compound by himself in a stand this season. I dunno why I posted that but it's a major part of my fall life :) (update - 12/3/2019: I am still chasing him into late season.)
 
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thenrich

Member
Aug 11, 2014
15
Central, WI
In regards to the Superior wood pellets I adjusted to the medium air adjust a bit higher and now everything burns to a fine powder. On the Maxim when you adjust the air higher the feed rate is also increased. So I'l see how that effects consumption with it burning a bit hotter.

As a side note: With the last couple of days with mornings below zero I did notice the unit kicking into high-fan mode (there are 3 on the maxim - high/medium/low. Each with their own individual air adjust). This happens when water temp drops below 20 degrees above set water temp. For this to happen it needs to be really cold and the in-floor heating in calling for demand. In high-mode even at medium setting it's like a blast furnace in there.
 

thenrich

Member
Aug 11, 2014
15
Central, WI
Brief update: All of winter is here with cold and snow. No issues to report. I did however stumble on a pretty good mix of fuel. I use 1 bag hardwood, i bag softwood and 1 bag corn. This seems to bring the best bang for the buck - burns really good. Kinda weird looking in the firebox and seeing clumps of pellets attached to a kernel of corn. Its like the kernel melts and the pellets stick too it. They remind me of little burning stars. After awhile the agitator breaks the clumps down it dust.

I've found the best setting for this mix is to adjust the air a bit higher then the feed rate. Super happy with everything so far. I know I can go a few days without doing anything to it but I still check it daily. I usually level off the bin with fuel. I also remove any ash at the end f the firebox agitator.