Intrepid II - Flue frame has cancer!

[DoubleClutch]

I have an Intrepid II Model 1308 and the piece of cast iron surrounding the flue plate seems to have gotten cancer. It suddenly seems to be growing and growing – expanding – and since there's nowhere for it to expand to, it's cracking and falling apart. (See photos.)

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Does anyone know:

1. Why it's doing this? and

2. Where to find a replacement piece? Black Swan and others don't seem to have it.

Thanks all, and stay warm!

 

[DAKSY]

You should be able to get a replacement Damper frame from Vermont Castings...

 

[Dakotas Dad]

Yeah, I bet a casting like that is only going to be found through the manufacturer. I bet that is a very warm spot during the burn, going to guess that it just failed due to thermal stresses. I wonder how hard it's going to be to get out and replace..

 

[jharkin]

The stove has been overfired. When abuse with high heat repeatedly the castings warp and burn though.


You can get that replacement damper housing from Woodman's - $30
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When you take it apart you are probably going to find it needs other parts, most likely the refractory and catalyst are shot. The damper plate itself, lower fireback and throat hood would be suspect as well (if they fit back in you are fine, if they dont fit when you try to reassemble they are warped and need replacing).

For the other parts:
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select Vermont castings from the left pulldown, then Intrepid 1308 from the right. You will an exploded view with the parts order list.


If you want help/advice doing the rebuild just shout, or come join the VC owners 2013 thread.

 

[jharkin]

There is a larger exploded view at (broken link removed to http://www.fergusonfireplace.com/ferfirpartslookuppage.html), and that is another source to get parts.

Looking at the exploded view, and the photos I think you are actually in luck vs us Encore and Defiant owners in terms of getting this apart. It looks like both the damper frame and lower fireback parts are held in with rotating clamps. My guess from the exploded view is hat this is the order to take it apart will be something like:

1. Unbolt the andirons to make room to pull parts out the front door. MIght need to lift out hte ash grate also.
   
2. Lift out hood.
3. Rotate clamps on lower fireback up, and pull out lower fireback out
4. Rotate clamps on the damper frame up, and pull out the damper frame.

All these parts may be gasketed and/or cemented in place. When reinstalling new ones use gasket or cement as you ofund it. You will need a good chisel set or (my preference) a dremel with grinding tips and a shopvac to remove old cement. If the refractory is crumbled replace that too, and regasket everything. Should be good as new and could be a one day job if no bolts break and you have the right tools.


BTW It could be a lot worse - many encores have the firebacks all bolted in, and the damper control mechanism attached. To get them apart also invovles removing the double wall inners side panels to make room and then unbolting and wiggling parts out at odd angles to free the damper mechanism.



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[elmoleaf]

Yup, cast iron eroding due to extremely high heat over prolonged period of time. My throat hood (the part immediately below your damaged area) looked like that after 20 years (the hood typically gets orange/red hot all the way through in my stove, as that's where all the gases exit through when damper engaged).
Not sure why you are getting such intense heat so high up as to cause that damage.....not normal. Are you not using ash pan and burning on top of a big pile of ashes? Is the damper never engaged and the stove always burned wide open? That'd be my guess. Or you had damaged or missing damper gasket in that area, causing a limited blast furnace effect in that area.

 

[DoubleClutch]

Holy cow, I had no idea I would get such helpful, detailed replies. THANK YOU!

FWIW, I contacted VC and ordered the part "Damper Housing" ... though as a special-order item it will typically take 4-6 weeks, the lady said.

I am saving this thread for reference when the part comes in. JHarkin, your advice on R&Ring the parts should be very helpful.

Elmoleaf, not sure what's causing the overfire condition. My guess would be the very tall stack (~36' x 7") coupled with the occasional coastal high winds...when it gets really cold and windy, the stove burns like an Atlas rocket booster – flue open or in bypass mode – and that may be causing it to get too hot, if overheating is the cause. I've actually considered installing a flapper in the black pipe between the stove and the wall for that reason.

Also, it seems like we're never able to maintain catalytic combustion for very long before the temp drops below 550° so we end up running the stove with the damper open most of the time.

Again, many thanks for all the help.

 

[jharkin]

You are very welcome, Ive been through a lot with mine the last few years and like to give back to the community. You can read the 2 threads in my signature to get a better idea of whats going on and what you are in for.

With that tall stack, consider installing a key damper to tame the draft. Later Vermont stoves have a small hole in the back of the stove just below where the cat is that you could use to install a probe thermometer to monitor catalytic temps. Condar makes these thermometers. If you are seeing iron glow red inside the stove the catalyst is probably running too hot, like 1800F+ which severely degrades its life. With the monitor probe you will catch this and be able to either lower the air setting or use the key damper to slow it down (or a combination of both). The cat is safe up to 1700 or so.

Once the load has burned down to coals and the cat cools off, no need to go to bypass. Just leave the cat engaged and open up the primary air to get some more heat out of hte coals before it burns down enough to reload. The cat wont be damaged.

 

[DoubleClutch]

Thank you. That's good information to have. I appreciate the help.