Hearthstone Mansfield - Cracked Ceramic and Controlling Burn

[smileti]

I'm on year two with a Hearthstone Mansfield and this morning when I went to reload it, a piece of the ceramic (from above the top baffles) was in the firebox. The stove is installed in front of a fireplace, and has a dedicated stainless chimney venting all the way up through the top of the stack (there's a cap on the ss chimney). There is a very good draft, so strong in fact that I had to install a stack damper. The stove got very hot for a short period of time the night before last, so my first question is: did the heat cause the ceramic to crack?

I'm burning very dry wood, and am having trouble keeping the stove in the "burn zone." With a full box of wood, unless I shut down both the stove damper, and the stack damper, all the way, just as soon as there are flames, the stove overheats, and quickly. This is somewhat of a pain in the neck, since I have to baby-sit the stove after re-loading. The night the stove overheated, I reloaded it (there was just a bed of coals left), opened the dampers, went upstairs to help my daughter with some homework, lost track of time, and by the time I came back down 25 or 30 minutes later, the stove thermometer was 700 and climbing). I also have a Phoenix, and can run that until I get a secondary burn going, and then damper it down.

Question two - is there anything I can do to better control the burn, or is this just the nature of my Mansfield Beast?

Questions three to ? - is the stove safe to use with a piece of the ceramic missing? Should I replace the entire ceramic plate, or cement the piece back in? Is it easy to repair or replace the ceramic? (And easy for me means under thirty minutes, with simple tools, and no need to lift more than say 30 pounds).

Thanks as always to all of you altruistic experts out there!

 

[Highbeam]

I have the little brother, the heritage and I can tell you that the high stove temps shouldn't have broken the baffle. It just sets in there on top of the tubes and only a physical impact can break it. You didn't say how big or where on the baffle this piece broke from. It could have been broken all along and just now fell apart. The baffle is pretty thick and can take some reasonable abuse.

You can repair the baffle with furnace cement. I used rutland black from a tub with great results to fill in craters where I punched it with a tool while removing the cotter pins holding the baffle in place. With a broken piece you will need to make an effort to hold the piece in place while the cement dries. Perhaps shove some wire into each side to brace the crack?

Obviously, the baffle should be replaced ultimately. It will be easier to replace than to repair.

Your lack of control is most likely due to a very good draft. How long is this chimney? Nobody really has control of a non-cat stove, If you fully load a hot stove with small wood then the dang thing will run away since you can't shut it off. If a single damper isn't enough then you can go the next step and obstruct the intake.

 

[smileti]

The broken piece is from the lightweight "thermo ceramic" plate that lies on top of the metal baffles - it's in there to keep the soapstone from overheating and cracking.

The stove dealer is getting me a replacement under warranty. It's difficult to put in a replacement the same way it was originally installed (when the piece is installed at the factory, it's laid on top of the baffles before the top soapstone tiles go on) so the dealer told me that he'll cut it half, and then I'll be able to slide the two pieces in. After they're in place, I'm supposed to cement them together. (That should be a fun time with my head in the stove, my fingers poking up through the baffles, trying to get two pieces of loose lightweight material to stick together with slow setting cement. Herding cats sounds less frustrating)

It doesn't seem like my one overheated burn cracked it. I think it was either cracked a bit already, or since the stuff is surprisingly delicate, I suppose a log might have banged against it.

I was able to stick the broken pieces back in and cover the cracks with some globs of fireplace cement, so I can burn in the meantime.

As for the hot burn, it is a great draft, and the wood is drier than what I burned for most of last year. So guess I'll just make sure I don't leave the stove alone with both dampers open for more than a few minutes.

Thanks for your thoughts.

 

[Wood Heat Stoves]

so the dealer told me that he’ll cut it half, and then I’ll be able to slide the two pieces in. After they’re in place, I’m supposed to cement them together

really?? i dont think so.
you just need to remove airtubes

5yr warrantee on that part

 

[smileti]

Hi Dave -
How do I remove the airtubes?

 

[Wood Heat Stoves]

send me an email adress, i can send you the tech service bulletin

 

[Highbeam]

Are you kidding Dave? Remove the tubes? Why not just slide the baffle between them or is this just not possible on that particular Hearthstone. I remove my baffle for every cleaning with ease. No tube removal and certainly no stone removal.

Either way, do not let this guy cut your new baffle in half.

 

[Wood Heat Stoves]

Either way, do not let this guy cut your new baffle in half.

agreed.

which model of mansfield do you mean Highbeam? the 8010 or the 8011?? no tube removalreally?

 

[Reggie Dunlap]

I had a Mansfield for 9 years. There were times when it was 20 or 30 below and I ran it at 700 degrees and hotter for days so I don't think one time at 700 caused your baffle to break. My first baffle lasted about 6 or 7 years and I don't remember having any problems installing the replacement. I don't think I even took the air tubes out.

 

[Highbeam]

My stove is the heritage and no tube removal is even possible much less needed to swap out the baffle. Well, you can remove the tubes if you remove the whole secondary cast iron manifold and split it in half.

You've got the TSB though so please let us all see how HS wants you to change out the baffle on that mansfield.

 

[smileti]

I'm going to repost this as a new query . . .

Well here it is a year later and I have another baffling Mansfield baffle question.

My cement job held through the season and a month or so ago I had my chimney sweep remove the broken baffle that I'd cemented back together, and install the new baffle board. I wasn't able to watch the operation and didn't think much about it until yesterday when I found a cotter pin in the dust under the stove. That prompted me to stick my head in the stove and check things out.

The new baffle board seems to be correctly placed on top of the secondary air tubes but I'm not sure the baffle support is correctly positioned. At the moment it's on top of the baffle board (holding it down) which seems odd since it's a "support." Is it supposed to lay on top of the baffle, or vice a versa? The baffle support can be slid forwards and back so I don't know whether there's an optimal position for it - if I slide it all the way forward, and center the baffle board from front to back, there's air space between both the most rearward and forward air tubes - in other words the baffle board is smaller than the rectangle defined by the secondary manifold. Is that correct? (Oh, and I have no idea where the cotter pin I found on the hearth came from as there's still one in the third air tube.)

Hearthstone's directions for baffle replacement aren't the best - no graphics - and the exploded parts view doesn't help either.

As always, thanks for any help you can muster.