Encore 2550 Rebuild Thread

The 'boss' suggested I post this here for reference. This is going to be snippets of a 2 month build log documented elsewhere, so apologies if some of the post seem incoherent. I'm just copying my own remarks.

This may take some time, so please bear with me.

The stove is a Vermont Castings Encore 2550 Catalytic. Purchased in 1997 and installed by the previous owners of my house. I inherited it in 2009. I have no idea how well it was burned or mainted before I got it, but do have the professional installer and FD inspection report from 97 so I know it was put in to code.


To start, I'll recap what I did from my other thread:

New cat
New refractory
New combustion hood
All new gaskets
Repaired seams
Rebuilt bypass
Rebuilt doors and regasketed glass
Blasted, clean and reinstalled all interior castings
All new bolts and hardware installed with copper a/s
Removed redundant pipe damper
Full repaint
Polished griddle
Lubed all moving parts with graphite
Check and adjust both primary and secondary thermostats

 

Starting at the end - the summary

Final Thoughts - Part I

Ok, so I'll add some final thoughts about the rebuild process and we can keep this here as a reference for other Vermont Castings owners.

Is this worth doing?
That all depends. For me I felt it was worth it because I inherited the stove with the house, Im handy enough to do all the work myself and the hearth is small and would be challenging to find another stove that fit well. I also only use the stove part time and the castings overall were in pretty good condition to re-use.

If you rely on the stove 24/7, if you have to hire the work out, if you have significantly warped iron, its probably not worth it.

What should I replace? How far to take the stove apart?
This is a tough one. It is often recommended that if you are doing this much work you should tear the stove apart completely and rebuild it like new. That's a daunting task I didn't have time for. Nor the rebuild manuals to be sure I did it right. If you are going to do the refractory though at a minimum you have to take apart all the internal castings and fireback. If any part of the fireback is warped you might as well buy the entire fireback kit, otherwise just replace any parts that are not re-usable.

Note that if you see signs that there are leaks in the outer shell (difficulty controlling a low burn in spite of good gasket seals, smoke test shows air being sucked in through panel seam, etc) than a full tear down rebuild is a must.

How long and how much?
I spread the work out over a couple months. Mostly working a half hour here or an hour there in evenings and on weekends, around work, kids and travel commitments. If you know what you are doing and work straight though I feel it could be a (long) weekend project.

My total spend was a bit over $400 including a pro-rated warranty catalyst, refractory box, gasket kit, adhesives, hardware and misc supplies. I had all the tools.

Where to get the parts?
Your local dealer, or.....

• Catalyst - I get mine from Condar. Can also go to Firecat, etc.
• Gasket kits and other parts-Woodmans Parts Plus, Fergusun Fireplace (Defiant's fav) have the best selections. Some parts are available at Black Swan also. I haven't bought from them but see that Mountain View carries most parts as well.

 

Final Thoughts - Part II

What about guides or manuals?

So far I cant find the service manual for the 2550, and from what Ive been told VC wont give it out (they want dealers to do the service).
I do have the following docs which should help:

• The instructions for the 2550 Fireback kit install. Note that it says nothing about cementing or gasketing the upper back- refer to Defiants suggestions earlier in thread.
• The manual for the VC gasket kit which should asnwer any gasketing questions and also has advice about aligning the door air manifolds, etc. (too big to attach sorry)
  
• The service manual for the earlier 2140 revision of the stove. The fireback catalyst acess, door glass are all different but otherwise its a good read and provides helpful insight into things like cementing panels and how to properly adjust the thermostat.

Final Thoughts - Part III

What tools and supplies do I need?

At a minimum:

• Shop vac
• Straight and Phillips Screwdrivers
• Socket set
• Allen key set
• Couple size cold chisels and a hammer
• wire brush
• Gaskets, Gasket adhesive, furnace cement, stove paint if applicable.

I strongly recommend:

• A Dremel rotary tool
• Dremel grinding bits - the #952 bits are perfect for cleaning gasket channel
• Dremel cutoff wheel (to cut new screwdriver slots in creosote encrusted window glass screws and cutting oversize bolts to length)
• PB Blaster or liquid wrench
• Rubber mallet (for pressing castings back in and settings the fireback wedges)
• Copper Anti-Sieze
• 1/4-20 and 10-24 taps and tap handle
• Replacement hardware (1/4-20 x 1" and 1/5" bolts, 10-24 button head screws x 1/4" & 1" for glass) - plain steel or stainless. no zinc!

To really make things easy:

• Drill or angle grinder with a couple size wire brushes
• Electric impact driver to break stuck bolts
• Graphite spray for the hinges, etc

 

My first port from the log

Ok, so the amount of buildup I got in my chimney last year prompted me to take the stove apart and contemplate a minor rebuild.

To set the background:

- Wood supply is good. Last year I was burning 2-3 year CSS wood, mostly oak maple and some crabapple that I cut myself.

- Stove seemed tight last year and was controllable. No obvious signs of leaks and all the door gaskets good.

- I did get weird catalytic behavior. Sluggish light off on big loads, smoke anytime below 1200F probe temp. I run a steelcat and its warped so Im considering sending it back on warranty.

- You can see there is a lot of black creosote in the firebox, but there was nothing but brown ash in the back of the stove past the catalyst and I was getting good 1100F - 1700F catalyst probe temps, once it lit off! - last year. Typically this stove runs with almost no flame in the main firebox when the cat is engaged however, which is I think why I get firebox buildup.

- Longer term I know the best bet with a VC is to replace it. Financially I'm not in a position to do that this year, but am willing to do a modest investment in parts if I can get it to last a couple more seasons.

- This is not our only source of heat. It gets used mostly on weekends only.

Ok, so to start with I did another good sweeping. I did a late season sweep last year and this time I got about 2 coffee cans of crusty black chips. Probably from only a half cord burning. I installed an outside outlet by the new patio so this time I setup the shop vac outside with a long hose through the window. So much cleaner!!!!

 

Here is what it looked like as I took it apart. I eventually decided to replace the cat and refractory, and rebuild/reinstall all the internal castings. Al the iron except for the cat hood was reusable.

 

All the parts out in the garage ready to start working... Didnt break a single bolt.

 

All the internal castings I cleaned up with a drill/wire brush and removed the old cement from the gasket channels with a dremel.

 

Originally I was going to leave the refractory for fear of the fireback job, but it was probably a good idea i did it.

OK, to answer my own question, I pulled the upper fireback. Bolts came out easy, and halfway out I gave the right one a tap with a mallet to break the cement bond. It was wrenching that casting out that is a $(*&%(&#@@. They tell you to just swing it out to the right, but when you try it feels like its hung up on the top edge. It hangs on a lip around the flue exit and you have to wiggle it forward slowly till it falls free, then pull it out at an angle till the damper handle slides out of its hole. The tricky part is that there is only one spot lined up with the ribs on the right side wall where it fits without bending that rod.

Here it is. A real mess but seems straight and crack free.


starting working on cleaning up the castings, this is going to take the most time of the entire job. The upper fireback is a real piece of work because there is so much furnace cement on it. This stuff is more of a pain to get off than gasket glue. I cleaned it with a wire brush and started chiseling off the big chunks. Neighbors probably think my garage sounds like a blacksmith shop.

Next step will be to use the dremel with a grinder and wire wheel and take all the mating surfaces down to bare metal.

Work continues. Old cat is on its way back to Condar on warranty and I ordered a the hood and a full gasket kit from woodmans. Fedex says a package is on the way but it doesn't sound heavy enough to include the hood... hope its not on long backorder.


In the mean time more work on the castings in prep for new gaskets. Goal here is to get every surface that will get glue or a gasket down to shiny clean metal. First up is the upper fire back. I chiseled off the big chucks with a a hammer and old screwdriver then use a grinding bit in the dremel to get the rest. I'll give the whole thing a once over with the wire brush when done.

I have a lot of respect for professional stove techs who can rebuild an entire cast stove in a day. I probably spent a good hour and a half just on this one casting and its not done yet. 3 more to go after that, and then the real messy job cleaning up the mating surfaces inside the stove.

 

Here are some shorts of the damper rebuild. I cleaned it all down to bare metal. took all the hardware apart and reinstalled with copper antisieze. Regasketed. Cleaned up the damper rod and lubricated all the mating points with graphite spray.

 

I was asked about operation tips at one point and replied:

Yes I do - see the metal rod below where the cat sits in my photo of the refractory. There is a metal button on the back casting you pop off and insert the probe. I use the Condar Digital monitor. Others cook up there own with a k type thermocouple and digital reader - parts available for around $30 through amazon (member Joful posted a sample setup last year).

For this stove I feel the monitor is a must have. Its much easier, and I feel safer, to set the air controls based on catalytic temp (rather than griddle temp alone). Because of the stoves design its possible for the griddle thermometer to be in the safe zone while the catalyst is at overfire temp. Without the monitor your only sign of trouble would be the sight of glowing cast iron through the window (bad!)

With the cat monitor operating the stove is simple:

• Start up a fire and let it burn wide open to warm up the stove
• On a new load you close the damper (bypass) when the probe reads 500F (I go higher on big loads).
• If the cat lights off properly you should see it rise to 1000F+ in 5 min or less, if it climbs slowly and stops around 800 that is a catalyst stall and you need to reopen the damper and heat it up some more then try again. Once the cat is active start closing down the air control in increments till you reach cruising. For me this is with the air between fully closed and 1/3 open, depending on how much heat you want.
• Any time you see the cat probe temp over 1600 you should close the air completely (1700+ is the danger zone)
• In cruising mode the cat temp will normally be in the 1100-1600 range (griddle might be 500-700 depending on how the primary air is set). During this part of the burn the air control will typically be almost closed but the stove is pumping out massive heat from the back casting due to the cat. Probe temp usually will slowly climb through the burn then peak and drop off fast. This part of the burn might be 1-2 hours for a couple splits or as much as 4-6 hours on a full packed load of Oak.
• Once the probe temp peaks and starts falling s you know the major out gassing phase of the burn is done. You still have hours of usable heat in the coals and at this point you can safely open up the air control to maintain griddle temp without fear of overheating the catalyst.
• Once the cat temp falls below 800 with the air control open the load is pretty much burned out and its time to reload.

rinse & repeat...



Yeah, I like to have either a mix of 20s and 16s or all 16s. If you have the 20s they will fill the lower box nicely but then you'll need a couple shorter splits to top off the box for an overnight load. If you have only 16s, do like Reckless, start loading everything to one side, then you can put a couple 16s in vertical on the opposite side to fill the unused space. Its also good to keep a pile of shorts and uglies around for this stove, to fill all the nooks and crannies of the unusual shaped firebox.

Don't be afraid to fill it to within 1/2inch of the top load door for an overnight load, once you are comfortable with how it burns on medium loads and have confirmed everything is tight. One rule of thumb I follow however is - bigger the load, bigger the splits. This is not a blaze king , filling it to the roof with kindling size pieces or 2x4s will overwhelm the cat with too much off-gassing and overfire.

If you want max heat output run half loads or less of smaller pieces so you can keep the air open and get more flame without overfiring the cat. Long term slow burns, pack as tight as you can with the largest splits you have.

 

Then it was door rebuild time.

So back to work it is. Tonight I started on the doors. Start by taking them off, plastic over the opening to keep the house clean, and start a couple hardware bags.

Main objective here is to replace the glass gaskets. Door gaskets I did a couple years ago so I was not expecting to do them again but the gasket is falling out in some places. I wonder if its the glue? I had used rutland back in the past but last year the local shop guys suggested to use this Meeco Red Devil stuff. Hope that lasts longer on gaskets. Might redo the who things since Ive got the door gasket material in the kit.

Anyway, the trickiest part is getting the small screws and glass clips off without breaking anything. Even though the galss burns clean, creosote tends to buildup along the frames and coats the screws. Do your best to chip it away and dont feel shy about tapping around the screws with a small chisel. The glass as we all know is ceramic and wont crack unless you give it a direct blow.

Unfortunately no matter how good I cleaned it up, some of the those button head philips screws are too fulll of buildup to get a good bite with the screwdriver. Whatever you do, DONT cut the heads off thinking you will just drill and tap new holes - these are very shallow screws and you would likely have to drill holes all the way through the door casting to get a tap to fit.

I have a trick to get this out. Read on in the next installment...


So the trick to get the screws out is quite simple. Its something I learned from working on R/C airplanes because we use a lot of small hardware, 2-56, 4-40, 6-32, etc and its easy to strip tiny allen head cap screws.

What you do is get a dremel cutoff wheel, and use it to cut a slot in the screw head. Cut deep enough to get a good bite, but not so deep you bottom out and weaken the head. Then find the largest flat head screwdriver that will fit and give it a turn. Even better, and what I did, is to use the electric impact driver again.

I got all 11 screws out without breaking a single one. I think I had to use this trick on 7 of them. All new hardware will be in order... Have to check the size I think these are #8 or #10.

So both glass panes are out and set aside wrapped in towels. I started cleaning out the first gasket channel a bit then called it a night.

I looked and Woodmans carries the glass screws for $5 a piece!!!!! (seriously?)

So instead I will but them from Amazon Supply a.k.a smallparts.com. I have to buy in lots of 100, but 100 screws are $6, with free 2 day shipping to prime members. I'm getting new glass screws and new 1/4 bolts for the sides and fireback. All in plain steel black oxide. If anyone is rebuilding a VC and needs extra hardware I'll send you some for the price of a stamp!

One side benefit of ordering though amazon is that I was able to get hex drive button head screws for the glass to replace the phillips. Easier to remove without stripping the next time....

 

More doors

Took a break last night to catch up watching all the recorded back episodes of Top gear on the DVR. Kids decided to sleep.

Tonight I'm back at the stove. Spent time cleaning out the gasket channels on the doors. I hadn't intended to do the door gasket at first (only 2yr old) but its lifting in a few spots and Defiant was kind enough to trade me extra for some bolts so what the heck. In removing it I found that what I thought was a bolt stub in one hole was actually gasket glue - a couple of the window bolt holes are through drilled into the center gasket channel.

This work went fast. Unlike the inner side gasket channels that took hours, these door gaskets I had done before with just enough glue and it only took 5 min each to clean them up.

The door is marked up a bit at the front and I took off some paint around the edges cleaning it so decided it would be a good idea to give it a fresh coat of paint while the glass is out. A quick wipe down and coat of paint only took ~10 min. Much easier and less messy to brush it on.... and man this has got to be the fastest drying paint Ive ever seen.


Tomorrow the new hardware arrives to I'm hoping to get the glass reinstalled, gasket the doors and put them back on the stove before the long weekend. After that family will be arriving and I need to start building the kids swingset so this might be it till I get back from my work trip.

 

And photos of the door work.

 

And then got the doors back in. Had to do some adjusting to line up the door airwash manifolds correctly with te air manifuld in the top front of the stove. And needed to do some grinding to relieve an interference point. Used graphite on the hinges and the doors are silent and smooth as silk.

 

At that point I took a break in the work to build the kids a swingset and fly to China for work!

 

When I got back it was into the end game...

I cleaned up the griddle by polishing with a wire brush and giving it a lite canola oil rubdown. I also removed that unneded pipe damper and painted the entire stove.

 

Then after a very messy and very thorough internal cleaning of the firebox, it was time for final assembly. I made a big mistake putting the upper fireback in and had to redo it. Notes below.

Ok so I found some time on the weekend between yard work and car work/ oil changes to start the final interior cleanup. I got most of the loose buildup off already, now the goal is to remove all the remnants of furnace cement from the upper fireback mounting surfaces and clean it down to bare metal so the new one will fit and seal right.

Plan will be to dry fit the upper fireback into place before installing the refractory or gasketing. I figure once that's all done I have only one shot to get it right if I'm cementing it.

with previous jobs, a dremel with a variety of grinding tips is almost a mandatory tool for this work. I put the shopvac outside with a long hose coming through the window and work two handed holding the dremel in my right and the vac hose in my left. Don't forget the mask and goggles too.

A couple findings...

First off, the lip at the top of the back sating that the top edge of the upper fireback hangs off is actually a half round groove like a gasket channel. Defiant, I know you stated before that you gasket the sides of the upper and glue the top edge? Or could I put a gasket in this top groove and avoid cementing it in?

Secondly a lot of the cement in the vertical seams between the back and sides was loose and falling out. If i had the luxury of time it probably would not have hurt to take this stove out of the house and break it down all the way but I cant start into that now. The back casting actually has a 1" flat overlap on the side panels with what looks like a double tongue and groove seal so I'm hoping this is not critical. I will grind all the loose cement out of the channel and lay in a new bead of furnace cement from the inside as insurance however. Not ideal but better than leaving it as is.


We are getting really close to the goal line now.

All the painting is done. I even painted the stove pipe stub and tee for good measure.

I did a test dry fit of the upper fireback. Now that I had cleaned out all the buildup and old furnace cement it actually went in very easy! Luckily not the swearing fest BBar had to go through on his 0028 - so I guess there was some logic in the design change by Vermont.


Next up I need to touch up the internal seams with furnace cement and install the refractory. Then gasket the sides of the upper, then run a bead of furnace cement on the top channel inside of hte back casting and bolt hte upper in.

Once that's done the rest of it should be not more than an hours work and we are ready to rock.

Ok, so we are almost there. I dry fit the upper fireback one more time, this time with side gaskets and bolts, to do a final fit check and check the operation of the damper. It was a bit tight but some work with the adjuster screw and a lot of graphite spray on the moving parts did the trick.

Then the fireback comes out, refractory goes in, and the two stainless sheetmetal heat shields. I laid a thick bead of cement on the upper groove inside the stove and put the fireback back in. Its a good idea to wait till you are ready for the final assembly to place the refractory, as the back of the fireback has a beveled/chisel edge that compresses the refractory opening slightly to make a gas tight seal.

Once its in tight, the side panels go in with a little encouragement from a rubber mallet and get bolted down. New hardware and copper antiseze everywhere.

Then use a small twist drill turned by hand to make pilot hoes for the secondary probe and cat temperature probe, install and hook up the secondary air (I get some closeup shots of the back tomorrow) and install the new catalyst. Its a tight friction fit.


BTW, those drywall screws that everyone loves to make jokes about in the VC refractory box where just there to hold it while the glue dries. That front panel is bonded to the box with refractory cement.

 

Like I mentioned, I screwed up and had to redo it. Idid the right thing and decided to redo everything.

Oh $&%#%#%$%$&#

I knew this was going too easy.

So we have a problem. When I put in the upper fire back, in the prcess of manhandling it into place the refractory box got tilted to the left about 1/4 inch.

The refractory box is sealed to the upper back well. Its not far enough out to cause any problems getting the lower to seat properly.
However it is tilted enough that the bottom of the box is not tight to the secondary air channel ribs, which means secondary air meant to feed the cat would leak right up the flue.

Even worse I only noticed after the cement on the upper hardened and I already made the secondary probe hole.


So I have two options:

1 take it all apart, grind off all the non cured cement again, patch the secondary probe hole, replace it all and do it over.

Or

2 Cut off a piece of the old refractory to stuff into the gap at the base and seal the secondary air channel.

Second choice is obviously a lot easier and I think would work just fine. I fear trying to rip it all apart and do it right I might just make it worse. Thoughts?



Yeah, probably a couple hours. I need to undo the bolts and pry the upper fireback to break loose the cement bond at the top, wiggle it out (should be easier this time without all the excess cement and creosote buildup around it), then use the dremel to grind off the fresh cement, and put it back in.

What caused it? The refractory box just sits in place. The back side of the upper firebox has a beveled edge that presses into the opening of the box, slightly crushing it to make a gas tight seal and also hold the box in place by a press fit. Now the way you put the upper in is you first slide the left side and damper rod into place and then swing the right side in and up - in that motion to push it up onto place it probably grabbed at the edge of the box and dragged it.

Now its in there so tight there is no way Im going to coax it back into its proper location without removing the upper. UGH.

 

So anyway I answered my own question - took it apart before work. It only took 15 minutes to pull everything out, and in the process I found that the top edge of the upper wasn't fully bonded to the cement as well - probably didn't put a thick enough bead down. Probably a good idea to redo it. Filling the probe hole will be easy actually, just cut a small wedge of refractory and stuff it.

I also noticed that the thermostat cable looks stretch out, as if I got it bound when I clamped in the right side panel. So good opportunity to adjust it, and fix the refractory and upper seal properly.

I'm now guessing that this will end up being an under 2 hour setback.

OK, so after we met last, I disassembled everything and ground off all the old cement. Then I cleaned up and regasketed the upper again.

Now I got the refractory box into place again. This time I notices that when pressed back tight at the top it could wiggle a bit at the bottom. I know the older models used kaowool strips to seal everything, the 2550 just relies on a tight press fit of the fireback. I want this thing sealed tight, so I used what I had and cut up some strips of condar catguard expanding gasket to hold it in place during assembly (not too much, dont want to crush the box.

Also cleaned up and places the 2 stainless heat shields. These are critical - dont leave them out. Its the only thing protecting the sides of the back casting from the direct blast of catalyst exhaust at up to 1,700F.

Now I put a good bead of cement in the upper channel again, this time abuot a half inch bead! so that I know I will get a good bond. The upper back goes in on the left, get the damper rod through the hole then swing the right up into place. This time I held the refractory down with one hand while lifting it with the other, and only once in place reach behind the stove to start the bolts. once its lightly bolted, check that the refractory is in position onle last time and make sure the damper rod moves freely then crank the bolts down.


I know I used enough cement this time because it squeezed out of the joint inside. Reach in with a finger and smooth it out and remove excess like you are doing a caulk job. Should be good and air tight.

The rebuild notes say the bolts should be snug, not tight. I will leave them tight till the cement cures than back out and re-snug.

A liberal coating of CRC spray graphite on the damper rod at all the moving points makes it work smoooth as butter

Put in the secondary probe, cat temp probe, catalyst, catalyst acess panel, bolt in the side panels (checking the thermostat cable is clear this time), pace the lower fireback and hammer in the wedges, place the hood, replace the ash grate, and bolt in the andirons.