jotul firelight 12 inner back plate installation

[Ashful]

It's hard to see exactly what you're showing in the picture, but I remember the design pretty well from owning a few of these in the past. Those holes behind the cat chamber are the fresh air intake for the catalytic combustor. The basic idea is that wood gas coming out of the firebox mixes with fresh air and burns off in the combustor. The catalyst helps to support this reaction at temperatures down to 500F, which would otherwise require temperatures over 1000F.

However, I believe there is a fatal flaw in this design. I melted several combustors, as I believe they're just a little too small for the size of the firebox. I could control combustor temperature if I only filled the firebox up maybe 60% - 70%, but I would often see unacceptably high combustor temperatures when I would fill the firebox. I had no issues with controlling the fire, it's a good stove in that regard, but running it low would sometimes cause the combustors to peak around 1800 - 2200, which would destroy them.

The typical advice you'll see folks give here is to open up the air a bit, to burn off more of the wood gas in the firebox, and reduce the load on the combustor, but I always found this just got the freight train rolling a lot faster and made it even harder to eventually bring things back down. I sometimes wondered if I would be able to control the combustor temperature better by partially blocking those holes, but never experimented with it. Designers of secondary burn stoves, whether catalytic or non-cat, walk a fine line trying to balance the fuel and air requirements of both the firebox and secondary burn system. I believe these Jotuls were early in the catalytic learning curve, and they got most things right, but not without a few issues.

It's also possible that both of my last two Jotuls had a leak, which caused these combustor over-temp conditions, but I highly doubt it. They'd have to have had the same issue, and both were kept in very good repair.

On the gasket, it was just pinched between the back plate and stove body, or damper frame and back plate or stove body. This is where you need to use bits of masking tape to hold it in place, while reassembling. Some have found it's easier to lay the stove on it's back while doing this part of the reassembly, and I'm sure it would be, but I always managed with the stove installed upright.

 

[meland]

It's hard to see exactly what you're showing in the picture, but I remember the design pretty well from owning a few of these in the past. Those holes behind the cat chamber are the fresh air intake for the catalytic combustor. The basic idea is that wood gas coming out of the firebox mixes with fresh air and burns off in the combustor. The catalyst helps to support this reaction at temperatures down to 500F, which would otherwise require temperatures over 1000F.

However, I believe there is a fatal flaw in this design. I melted several combustors, as I believe they're just a little too small for the size of the firebox. I could control combustor temperature if I only filled the firebox up maybe 60% - 70%, but I would often see unacceptably high combustor temperatures when I would fill the firebox. I had no issues with controlling the fire, it's a good stove in that regard, but running it low would sometimes cause the combustors to peak around 1800 - 2200, which would destroy them.

The typical advice you'll see folks give here is to open up the air a bit, to burn off more of the wood gas in the firebox, and reduce the load on the combustor, but I always found this just got the freight train rolling a lot faster and made it even harder to eventually bring things back down. I sometimes wondered if I would be able to control the combustor temperature better by partially blocking those holes, but never experimented with it. Designers of secondary burn stoves, whether catalytic or non-cat, walk a fine line trying to balance the fuel and air requirements of both the firebox and secondary burn system. I believe these Jotuls were early in the catalytic learning curve, and they got most things right, but not without a few issues.

It's also possible that both of my last two Jotuls had a leak, which caused these combustor over-temp conditions, but I highly doubt it. They'd have to have had the same issue, and both were kept in very good repair.

On the gasket, it was just pinched between the back plate and stove body, or damper frame and back plate or stove body. This is where you need to use bits of masking tape to hold it in place, while reassembling. Some have found it's easier to lay the stove on it's back while doing this part of the reassembly, and I'm sure it would be, but I always managed with the stove installed upright.

 

[meland]

Thank you. I'm learning a lot . Of course, it's a bit too late. I just realized the damper frame is warped. Tried to buy new from local dealer, and online from dealer you suggested in other feed, but its discontinued. My options on this stove are dropping quickly. Thankfully I was able to put a hold on the other parts I am waiting for.

 

[Ashful]

Thank you. I'm learning a lot . Of course, it's a bit too late. I just realized the damper frame is warped. Tried to buy new from local dealer, and online from dealer you suggested in other feed, but its discontinued. My options on this stove are dropping quickly. Thankfully I was able to put a hold on the other parts I am waiting for.

Not sure what your financial situation is, but I managed this by buying a third Firelight 12, to use as a parts stove, in support of the two I was burning. Parts I couldn’t buy new, or where I didn’t see value in using new, came off the parts stove.

Also, during the few years I owned them, Jotul roughly doubled the price of every part to repair them. Worst was the delicate cat chamber, which went from $250 to $450 in one or two years.

I was just waiting for an acceptable looking top-exhaust front-loading cat stove to hit the market, of which there were none 2011-2014. When the Ashford hit the market, I knew it was time to sell those beautiful but expensive old Jotuls, and jump into something that required a lot less repair time and money.

Before you get entirely discouraged, note that there are people running Firelight 12’s without issue, or at least apparently unaware of any issues they may have. I’m not sure what combustors they’re running (probably completely depleted, in most cases), but they are out there. Maybe they’re running lower BTU woods?

 

[meland]

Not sure what your financial situation is, but I managed this by buying a third Firelight 12, to use as a parts stove, in support of the two I was burning. Parts I couldn’t buy new, or where I didn’t see value in using new, came off the parts stove.

Also, during the few years I owned them, Jotul roughly doubled the price of every part to repair them. Worst was the delicate cat chamber, which went from $250 to $450 in one or two years.

I was just waiting for an acceptable looking top-exhaust front-loading cat stove to hit the market, of which there were none 2011-2014. When the Ashford hit the market, I knew it was time to sell those beautiful but expensive old Jotuls, and jump into something that required a lot less repair time and money.

Before you get entirely discouraged, note that there are people running Firelight 12’s without issue, or at least apparently unaware of any issues they may have. I’m not sure what combustors they’re running (probably completely depleted, in most cases), but they are out there. Maybe they’re running lower BTU woods?

Thanks Ashful. I'm looking for a used one all over North East now, but with no luck as of yet...

 

[Ashful]

I remember when I was looking. Nothing for 6 months, then two or three fell into my lap in short order.

 

[NHJotul]

Ashful, I am able to run a full load in the jotul without it overheating. However, it required that there be a really good size bed of coals. Which usually meant that I would load it with a small load when I go at home. Throw more on here and there which meant I could flip back to the catalyst leaving the air supply set to low the. Load it to the brim later that night and immediately flip back to catalyst and I wouldn't even touch the air supply and still have it on low. She would creep up to the 1600 +- then go back down between 800 and 1000, the bed of coals would almost reach the doors and they would roast the wood above slowly and last the whole night.

Once had the coals up so high, I wanted to do some work on the stove the next day, like cleaning the windows, so I left it on high from 10:00 at night and around 11:00 the next day I still had a huge bed of coals. I believe the cat was a little congested from ash and that is why. Either way threw in the back up so I can clean the other one in viniger for the next cord. Seems to be the one issue I have with these clearskies cats, they collect ash like crazy and if you flip too early and they get covered in soot, you can burn it off but they need to be cleaned after.

 

[Ashful]

Once had the coals up so high, I wanted to do some work on the stove the next day, like cleaning the windows, so I left it on high from 10:00 at night and around 11:00 the next day I still had a huge bed of coals. I believe the cat was a little congested from ash and that is why. Either way threw in the back up so I can clean the other one in viniger for the next cord. Seems to be the one issue I have with these clearskies cats, they collect ash like crazy and if you flip too early and they get covered in soot, you can burn it off but they need to be cleaned after.

Are you certain it's ash? One of the things I liked about the downdraft design is that mine never got any ash on them, all ash caught up in the exhaust stream would simply fall to the bottom of the cat chamber, as it did the u-turn to go back up thru the combustor.

I could see them getting clogged very easily with creosote, the way you're running, though. Closing the bypass on a fresh load would really drop cat temp fast, and would likely cause it to plug with creosote, I would think. Usually, a full fresh load will want at least 5 -10 minutes on bypass, to get warmed up and bake off at least some of the initial moisture, before re-closing the bypass.