Jotul 118 CB secondary air failure

[stecy]

Well into last season the burn characteristics of my 2 yr old Jotul 118 suddenly changed. After some head-scratching, it became apparent that the small blue flames indicative of the proper functioning of the secondary air system were absent. A quick check of easy-to-reach places where the air intake might be obstructed showed no obvious problems. Fearing that a major dismantle would be necessary to find the problem, and as the stove continued to put out heat, I just limped thru the last couple of months. Now the time has come, and I need to get it fully functioning before winter is here.

Searched for existing posts on this problem, but couldn't find any discussion of this problem. Anyone has any tips for what might have gone wrong, or the best troubleshooting sequence to follow?

TIA

Steve Clay-Young

 

[begreen]

Sound like something has plugged the secondary air supply. I have never worked on this stove, but it appears that the tubes get air through the back of the stove. Is this correct? Can you pull the back plate off and see if the secondary air entry is plugged with dust bunnies? Another thing to check is to be sure that the top baffle and blanket are correctly in place. If the fire and wood gases can go behind the baffle, directly up the flue, they will. I'd give the stove a thorough vacuuming out. Then pull the secondary tubes and use compressed air to blow out the tubes and their intakes. Then reassemble, paying close attention to the fit of the upper baffle and blanket, they should be tight to the back of the stove. Then reinstall the air tube assembly.

 

[stecy]

Thanks, BeGreen, for the suggestions.

Wasn't sure whether is was OK to remove the secondary air tubes for inspection, but with your encouragement, I'll go ahead. There are two tubes along the sides and one across the front. I did notice that the crosswise one was not seated fully in it's connections to the others. Perhaps a weld broke. The front tube is placed in such a way that it gets struck quite easily when loading wood. One post a while ago praised the design of the secondary air system in this model, but frankly it looks to me to be a weak link.

As it happens, several days a week I am at the in-law's, where I load one of the original 118's, which is as good as new though 25 years old, and then I come home to my 2 year old 118 CB model that is giving trouble already. A noticeable amount of firebox capacity has been sacrificed to the Clean Burn system, as well as reliability. Of course I value low emissions, but the first cost is not the only additional price to be paid.

Steve

 

[begreen]

The original 118 and 602 designs are tough, good performers. But will a little care the CB models can be good heaters too.

 

[Corie]

I've completely rebuilt the stove you have from the ground up.....let me know if you have any questions, etc.

I can tell you that there aren't many places that the secondary combustion air can get plugged. I'm hoping of course that you have the flashfire system at the correct setting; the back plate of the stove (outside rear of the unit) seals the secondary combustion feed channels. Perhaps there is an air leak there and the air is taking the path of least resistance?

 

[stecy]

Corie

With you as a resource, I will in the next week or so pursue this till I find the problem.

Have already checked all the obvious places for leaks or blockages. It worked fine the first season, so I believe I have a handle on the proper settings for primary & secondary air.

Do you have any thoughts regarding the crosswise air tube becoming detached from the lengthwise ones? I noticed this about the time the secondary burn ceased to function. How are these attached? Are they welded? Some sort of clamp?

Steve

 

[stecy]

Well, I finally got to do a disassembly of the secondary air system, and found no clear cause. Frustrating - I was hoping to find a smoking gun.

There was some fly ash accumulated in the stainless tubes, that possibly could have blocked air flow. On one side, the rope gasket that seals the rear end of the tube to the secondary air chamber was degraded - may have been leaking. The crosswise air tube apparently just sits on notches in the lengthwise ones - no positive connection - and it was not seated fully. All three tubes are slightly warped, but it is hard to imagine that this is not normal, given the heat to which they are exposed.

Now I am wishing that I had not removed the back panel that encloses the secondary air chamber, as it turns out that it is sealed with cement, rather than a gasket; but at least I know that there were no obstructions in there, and that the 3 position air shutter operates as it should.

So, unless someone can offer anything else to look for, I guess I'll just put it back together and hope for the best.


Corie, this stove has only been on the market for a couple of years, so yours couldn't have seen that much use - what led you to do a complete rebuild?

Steve

 

[stecy]

Upon reassembly, the only thing that I can definitely point to is that the crosswise secondary air tube will not fit into the notches cut for it in the lengthwise tubes. This problem was evident before disassembly, and after cleaning & inspecting everything, it still refuses to sit where it is supposed to. Very frustrating. I almost wonder if the factory cut the notches incorrectly - this was an early unit, bought in Nov 05. Sure would be nice to have a current production tube to compare mine with.

Anyone have any ideas?

Steve

 

[precaud]

Corie, this stove has only been on the market for a couple of years, so yours couldn't have seen that much use - what led you to do a complete rebuild?

Industrial espionage.

 

[webbie]

Did you see a major change in the amount of smoke or creosote?
If not, it could be differences in the chimney draft, wood species, etc.
These are fairly simple designs and usually just work.

 

[stecy]

Craig

Yes, there was a change in the smoke. Originally, when the stove was up to temp, and the secondary air knob in the (normal) middle position, very little visible smoke could be seen coming from the chimney (6" Metalbestos). Last season, it seemed like smoke was visible most of the time, and that struck me as a major clue that something was wrong. However, I when finally swept the chimney just the other day, to my amazement there was no more creosote than before - which is not much at all.

Perhaps you are right that variations in firewood may be playing a part. Mostly I burn 1 year old wood, but at times it can vary from 3 years to 6 months.

There is absolutely no doubt that there is something wrong with the fit of the crosswise air tube to the notches in the lengthwise ones. Having taken things apart and reassembled them, this is looking like a manufacturing defect to me. The net result would probably be less secondary combustion at the point where the smoke rounds the front of the baffle - presumably the hottest point in the path. However, given that there was not markedly more creosote, that may not be quite as important as I thought.

Still, it bugs me that the air tubes do not fit together properly - this has to be compromising performance to some degree, even if not as much as I suspected. The stove was bought in Nov of 05 from Nichols Hardware in Lyme NH, who subsequently exited the retail hearth trade to focus exclusively on importing wood boilers. Jotul offers a 10 year warranty on manufacturing defects, and as three other local dealers have been of no help whatsoever, it would seem like a matter to take up directly with the importer. However, they offer no contact information on their web site - not even an indication of where in the country they are. All very frustrating. Do you have any contacts at Jotul USA?

Thanks

Steve

 

[webbie]

The dealer is supposed to do that job (of taking care of you) and, if not, they should give you contact info to get to your area rep (factory rep).
Jotul has a number listed around the web:
http://www.manta.com/coms2/dnbcompany_cm5cqp

however, it is likely to be very busy at this time of year. They (like most stove companies) have tech people who are supposed to talk to dealers only.

If I were you I would give it one more chance through the dealer you bought it from...and let them know you are going to have to call the factory if they cannot help you...ask for a call from (or to) your factory rep (the dealer surely knows his or hers)....

If not, give Jotul a call. The idea here is (obviously) to get someone who cares. The factory is not happy with dealers who do not do their job.....

Oh, my contacts there are in the ad and graphics dept - BUT, if you do not get satisfaction shoot me a PM and I'll try to bump from that end.