Enviro Cabello 1200 burning too hot

[Dan-4444]

Hello and thanks in advance for the assistance, this forum is an amazing source of info!

I have an Enviro Cabello 1200 fireplace insert that imo is burning way to hot and am wondering if anyone else has seen similar issues with this stove. With the damper fully closed it is not uncommon to see temps measured at the base of the chimney (about 1 inch from the firebox) in the 725-775 degree range.

Some background info on my setup:
I purchased the stove "used" on Craigslist in 2015, although it had never been fired. The guy didnt measure correctly and it was to big for his application. It was installed by myself into a 2 story colonial, approx 1800 sq ft. The chimney is a tile lined 8x10 and is about 25 feet from the stove to the top of the chimney. I installed a 6" ss liner with an insulating blanket along the entire length with a top cap. There are no chimney dampers, only the single air control on the stove. I have added an electronic thermometer for better temp monitoring and alerting of high temp (>775 deg F). Ever since day 1 this stove has never given great control, but it seems to get a little worse every year. I didnt add the thermometer until about 4 years ago, so for the first few years I don't know exactly how hot it was burning.

My fuel:
Generally I season my wood 18-24 months under a 3 open sided pavilion and generally burn oak, pine (80%) and the other 20% are a mix of birch, beach, cherry, elm, poplar and whatever else I can find. The issue doesnt seem to change much between the pine and oak. Actually last year I burnt about 95% pine, and this year I'm back to mostly hardwoods.

My routine:
Cold start with crumpled paper, small kindling and the rest of the stove filled with wood. Start with damper wide open and door cracked. Close door at about 200-250 deg, close damper fully at about 300 deg. Then it's off to the races with the temp. Depending on the temp outside, my stove temp will climb usualy to about 650 deg before starting to taper of and head back down as the wood burns down, with the damper fully closed.

Warm reloads:
Obviously quite variable, but if I attempt to reload the stove when it is 350 degrees or more, this is where I really run into problems. Whenever I fill the stove, I do FILL the stove. Given it's small size, i like to extend runtimes as long as possible. Once the fresh batch of wood gets going, even keeping the damper closed entirely, there is no way to keep the temps down. This is very frustrating in the colder temps as I'd like to keep the stove hot, but not melting down hot, especially overnight.

What I have tried:
Door gasket. I didnt think it was bad, but I replaced it anyway, no real change. Pushing on the door makes no diffrence in the burn.

Door tightness. It seemed okay, but had gotten a little loose over the years, so I tightened it a whisker, no change.

Inspect entire stove. 2 years ago I removed the entire stove, took the bricks out, sealed the air inlets, and put a vacuum on the chimney outlet. I searched with smoke to try and find any air intrusion, but could find none. The welds looked good, there were no cracks in the firebox.

Chimney to firebox gasket. This has gone bad a few times so I have replaced it, its currently in good condition.

Verified damper operation. It seems to be closing as far as it was designed to close.

Kinda verified my thermometer. I can see the top of my stove/base of my chimney just start to glow at about 775 degrees. Less than 500 degrees I can verify its within 35 degrees of an infrared thermometer.

The front air tube for the secondary burn needed to be replaced last season as the heat finally got to it, no change in control.

The fiber baffles have been replaced 2-3 times as they just start to crumble with age, no change in control with new baffles.

One inner heat shield was replaced last season as the heat had gotten to it as well, no change.

Other info:
I've been burning for about 15 years at 2 diffrent homes with 4 diffrent stoves. 2 stoves were circa 1970's, one was a 2010ish airtight Tractor Supply special (loved that stove) and the Cabello with the hot issue. All the other stoves, closing the damper would essentially snuff out the fire.

Theories on the problem.
1. I just have to much draft with the 25 foot chimney.
2. The stove is a poor design and just let's in too much air, unlikely because I haven't seen anyone else complain. But in tearing the stove apart 2 years ago, I did find it interesting that the damper does not shut off air to the secondary burn tubes. Is this normal for this type of stove?
3. I'm nuts!

Summary
Sorry for the long post, but I'm running out of options with this stove. Before I toss it into the truck and cash it in for scrap I'm hoping someone can steer me in a better direction. Hopefully there is something obvious I'm over looking.

Cheers,
Dan

 

[moresnow]

Welcome to Hearth Dan. Sounds like a frustrating experience. I have zero hands on time with this unit. I do see a item to check in the operators manual. Under Installation (pg 6) the literature indicates that there are 2 rivets that secure the unit to the shipping pallet. These are located inside the firebox and need factory supplied rivets installed after the lags are removed. Installing the rivets is done to seal the unit. Guessing you have verified these were installed as you bought this used?

https://enviro.com/custom_content/docs/manuals/C-14580%20Instruction%20Cabello%20Insert%20Owners%20Manual.pdf

Note: Before the bricks are re-installed, supplied rivets (Figure 7) must be placed in the holes which the lag bolts were removed from. This is done to seal the unit and make unit burn more efficiently.

 

[Rickb]

I believe you are seeing a issue do to your tall chimney.
Yes it is normal in secondary tube stoves to not allow the secondary air to totally close.

Your easiest solution is going to be installing a shot section of pipe with a manual damper in it just above the stove and then extend the handle through your surround. I have seen a few posts on here where the OP had to do the same thing.

Something like this:
Amazon product ASIN B003UL1TWY

 

[shortys7777]

The chimney throat is glowing at750 degrees? I have enviro kodiak 1700 insert. I get it pretty hot. I take my temps with the heat gun just above the door. I gave up on trying to get a reading at the chimney under the little opening. I see anywhere from 420-600 plus. I like to keep it at 500 or so but don't usually get scared unless it goes over 650. I forgot what temps I get at the same place you are getting yours at. When I start a cold fire I basically shut the door after a minute if the kindling is fully started, sometimes waiting 3 minutes or so but usually not much longer.

If I reload on a big bed a coals I turn the air down pretty quick. Have you tried reloading without the damper fully open? Shutting the damper 75% or more as soon as temps creep? I burn dry oak and maple mostly and If I close it up quick it kind of puts the fire out. If I wait to long I see temps continue to rise with a fully closed damper. Worth a shot maybe? My chimney is 15ft though.

 

[DuaeGuttae]

Like Shorty, I have an Enviro 1700 insert, but like you, I’ve got about 25 feet on my chimney. Even in our mild Texas weather, it drafts really well. The draft increases with the cold, and during February’s freeze where we had a week in the single digits, teens, and twenties, we burned it hard, but we have never seen any part of it glow. I used to monitor temperatures on it with an infrared thermometer, but I’m afraid the thermometer gave up the ghost, so I can’t check anything at the moment. (And our weather is warming, so I’m not sure we’ll burn much if at all the next few days.)

Moresnow brings up an excellent point about the rivets. You mentioned removing bricks and sealing air inlets. Is that what you were referring to?

I wonder if part of the issue that you are seeing is due to packing the small firebox too full. I’m not sure about the Cabello 1200 instructions, but my insert tells me not to load above the firebricks. I burn a lot of gnarly live oak and cedar with all sorts of knobs and protrusions, and a piece will stick up here and there, but I don’t pack it to the gills. I live in a milder climate with really high btu wood and a larger firebox, so I have that luxury. I’m wondering, though, if the glowing stove outlet is a combination of tall chimney with strong draft and wood packed higher than it should be.

I haven’t had my insert long enough to say how well my baffle or tubes will hold up, but with the replacements you mention, it sure sounds as though you have been suffering with an overfiring problem. Reloading when the coals are 350 sounds like a recipe for creating a problem.

The advice for a damper sounds good if your system has the room for it. Mine was such a tight installation that we wouldn’t manage, and Shorty’s advice to keep the air supply limited on reloads is good. We don’t open to 100% if we have abundant coals, and I’m pretty aggressive in cutting the air back when the wood is catching. You could try supplying less air at the outset and damping down fully earlier. Sometimes when I damp down my fire looks like it is suffering, but if it doesn’t keep dying I’ll leave it damped down, and it recovers.

It sounds like you might be pushing a small firebox too hard by having to reload before coals are burned down enough, and the strong draft on a tall chimney would compound the problem. EPA stoves are different animals from the old air tights. You won’t snuff a fire in them after it has gotten going. From my experience with the Kodiak, it’s not a poor design, but it is different from the Lange I grew up with. So I’d say you’re not nuts, but the stove isn’t poorly designed. You may have too much draft, but you might be able to improve things by more aggressive air control early in the burn. Definitely check for the holes under the firebrick if you haven’t done so already.

 

[begreen]

It's a great stove but like several Canadian designs, it's an easy breather. It works well on a short chimney, but 25' is pushing it.

Have you checked to verify that the shipping bolt holes under the left and right front bottom firebricks have been plugged? There is a rivet on each side that is supposed to go there according to the manual. I haven't done a deep investingation into this stove but if typical, there may be a boost air port feeding at the bottom of the fire, typically at the front of the firebox. If so, the intake is usually a small hole underneath, front and center. If you can locate that, cover it up with a magnet and see if that tames the fire. With strong draft boost air is often overkill on an easy breathing stove with extra strong draft. In some cases the solution has been to put a key damper in right off the flue collar and then rig up a control rod that extends through a hole drilled in the surround.

Other than that, try closing the air sooner and burning larger splits, tightly packed.

 

[Dan-4444]

Thanks everyone for the info. Yes I do remember the rivets, they came loose in a bag of parts and just set into the holes and the bricks covered them. I have considered putting in a damper on the exhaust but have been leary for 2 reasons; first I have very little room to work with as my fireplace is small and second I'm worried they will leak exhaust into the house. The insert has a fan that blows right past that spot and whenever the gasket between the firebox and the collar gets bad, I can smell smoke. Do those dampers usually seal pretty good? Years ago on a diffrent install I had one of the ones you drill 2 holes and insert the rod through the pipe and damper, but I remember it not being very tight. When I did my "test" of the stove integrity with a vacuum I sealed every penetration including the damper inlet, the secondary air inlets, the shipping holes, the door and then pulled the vacuum through the exhaust hole. I used incense for a smoke generator and went all around looking for any movement around the welds and seams but couldn't find any. Great idea on the boost air port, I think I recall seeing a small hole (maybe 3/8") next to the damper hole on the bottom.

Thanks again for all the tips, at least I have a baseline now. Seems as though i have too much draft and need to cut the airflow somehow. Are chimney top dampers a thing or is that taboo? Running outside to tweak it isn't appealing, but if I could dial it in and maybe set it and forget it. I will try some modifications in the coming weeks and post my results.

 

[Dan-4444]

Maybe something like this would do the trick: https://www.roofingdirect.com/shop/drop-in-damper

 

[john26]

Maybe something like this would do the trick: https://www.roofingdirect.com/shop/drop-in-damper

I think that would be hard to operate with an insert especially with the baffle board. Even if you ran the cable through the baffle board there is not much room to get to access the cable with a load of wood. Your liner would have to be pretty strait other wise it would rub on the bends. Not sure how you clean the chimney but that will not get along well with a soot eater. As far as smoke leaking into the house I don't think it will matter much if the restriction is a the top or bottom of the chimney and it appears to be only open or closed with no in between.
Here is a thread where Installed a key damper in an appliance adapter, it works well no issues so far. I always open all the way for new fires and reload. I have opened the door with it closed experiment very little smoke roll out, usually if reload is too early.
https://www.hearth.com/talk/threads/insert-key-damper-install.186463/

 

[Dan-4444]

I think that would be hard to operate with an insert especially with the baffle board. Even if you ran the cable through the baffle board there is not much room to get to access the cable with a load of wood. Your liner would have to be pretty strait other wise it would rub on the bends. Not sure how you clean the chimney but that will not get along well with a soot eater. As far as smoke leaking into the house I don't think it will matter much if the restriction is a the top or bottom of the chimney and it appears to be only open or closed with no in between.
Here is a thread where Installed a key damper in an appliance adapter, it works well no issues so far. I always open all the way for new fires and reload. I have opened the door with it closed experiment very little smoke roll out, usually if reload is too early.
https://www.hearth.com/talk/threads/insert-key-damper-install.186463/

Great post, thanks for sharing. I'm starting to lean toward that idea, after looking at the drop in chimney top dampers I have concerns. Is your damper control accessible from the front of your stove / do you have a finished pic? Do you find you change the setting often, or is it more of a find a sweet spot and leave it there for the season? I would need to modify the exterior of the stove to accommodate this sort of damper with external control, so before I drill I'd want to measure 3 times.

 

[john26]

Here is a pic of it with my PE insert I also used it on the Lopi that was previously installed. My chimney is 28' I always open 100% on start up and reload usually after the fire is burning good and supply is closed down, I close it all the way. After I start my fire and there is good char nice hot fire, I close my supply air next close my air boost then flue damper last. This is my procedure on most every fire.
the damper handle is centered above the door I will try to get a close up later.

 

[john26]

Here is a pic with the Lopi and an up close pic

 

[Dan-4444]

So ended up installing a 6" damper yesterday. I reloaded the stove this morning on coals and left both dampers open for about 3 min, then closed both when the temp as about 275. An hour later I'm at about 750 degrees. So that didn't work. I was able to verify the damper is closing fully before I put everything back together. And it's only about 32 deg outside. Only other thing I can think to try is the block off plates like John26 did in his install, would those holes make that much diffrence?

 

[john26]

If I am burning too hot I sometimes open the flue damper and primary air to send the heat up the chimney, I then close the flue damper first then slow cut back the secondary incrementally in hopes of slowing the draft and secondary burn down. This seems to help some. Blocking the center off on the damper should help some as well. I have read threads on here about 2 dampers so I figured blocking the center will not hurt it definitely is not enough to smolder the fire. Is there any way to block your air boost off? I made a block to open and close it on my PE.

 

[EbS-P]

Just verifying that your temp probe is on the outside of the insert collar. That area may be the hottest part of the stove. My jotul the hottest part is regularly 100-150 degrees hotter than where you are instructed to measure temps. If you have the probe in front of the outlet and between the jacket and the steel firebox that very well could be the hottest part of the stove. I think measuring flue gas temps it’s probably best as you get near instantaneous response to inputs and you can tell when to turn down the air sooner. If you are waiting until that spots hit 275 flue gas could be north of 900 and could have been there for some time.

I am about to install a damper as well. My plan is to find a setting on the 6” damper and leave it there as best I can. I won’t be opening it up at startup. A top down fire is all I need to get a good draft going.

Evan

 

[begreen]

The probe is reading at the hottest point in the stove. Do you have an IR thermometer to verify the probe accuracy?

I think the stove has boost air dog house at the bottom front of the firebox, but am not sure. Can you verify? If so, what is the size of the hole feeding boost air into the fire?

The dog house is the bumpout circled in red here

 

[john26]

Here is a few pics of the air boost block off I made for my PE not sure how yours works