Fixing too much draft...

[EJL923]

I've had my insert for a few years now. Its a little undersized for my home, but the biggest thing is the fact that my chimney drafts like no other, reducing my burn times. Been thinking about upgrading, but until I do I want to fix the draft issue. Ive discussed this before, but I'm finally going to do it.

There are two ways to combat this, install a flue damper, or add adjustments to the stove. And yes, i checked the gasket.
Adding a flue damper will allow me to essentially lower the draft of the chimney, but i am afraid that it would lower the temperature of the flue gasses due to the restriction and in return increase creosote.

Adding adjustments to the stove is the second idea. The Rockland has three air inlets, Primary, Secondary, Pilot. The only one that is adjustable is the primary. The pilot is two holes in the bottom front. I can adjust that by inserting screws into the holes. I usually burn with one blocked. The secondary air is an open hole located in the back of the stove. I was thinking about adding a sliding plate to adjust the size of the opening. it will require some experimentation to find the right settings, but very doable. Any adjustments will be reversible, meaning i can sell the stove as stock. The sliding plate allows me to

I would like peoples thoughts on each idea. I think its best to do this on the front end, the stove.

 

[mellow]

Overdraft issues with inserts has always been a tough one. Installing a damper behind a surround presents its own set of issues. Will you be running it with the surround off?

 

[EJL923]

If a damper was used, it would be my hope that i could adjust it to a normal draft and leave it. I know that prob wont happen, but maybe. I have an arched fireplace as you can see in my avi. the surround stops about 3/8" short of the top of the arch. I would fabricate a rod which could be inserted thru the opening for adjustment. Im sure something else could be done as well. Point is, if a damper was the way to go, the surround would be the least of my worries.

 

[begreen]

Another option might be to adapt the primary air control so that it admits a bit less air to the fire in the fully closed position. You could use a bit of metal tape to test this. Don't block it off completely. Often just blocking of another 20% will make a large difference. Once the correct percentage of blockage is found for this installation the tape can be replaced with a less temporary solution.

 

[EJL923]

The Rockland has a front slider made of cast iron for the primary. Actually, the shop who did the installation ground off the limiting cast iron bump because of my draft. I marked the location of the original stop location for reference. It didn't make too much of a difference. I think the key is going to be making the secondary air adjustable. That is a wide open hole on the back. Correct me if im wrong, don't some stoves have a single air control which bumps down both the primary and secondary at the same time?

 

[begreen]

The only stove I know that does this is the midsized 2 cu ft PE stove.

 

[EJL923]

bg, in terms of my two options above, and taking out difficulty of installing either one, would you add a damper or have adjustments on the stove?

 

[begreen]

Catch me up on the installation. How tall is the liner on the stove? How has it been determined that the shorter burns are because of draft?

Installing a damper will be semi-permanent and a bit of work. It there room to add a 6" damper pipe at the flue collar? If the air control has already been modified and you are still experiencing draft issues, then restricting the flue is probably the next step I would take.

I have not tried this, so it's an open question. I'm not suggesting it, just asking. Has anyone tried restricting the flue by installing a stainless baffle at the top of the liner? It would be removable for cleaning.

 

[EJL923]

I have a 24' liner, on an interior chimney. Its not insulated, the chimney was checked out before installation. Sealed up top and a block off down below. I guess i have to say its not just shorter burns, its also not being able to control the fire during peak burn. You may have seen other Rockland owners talk about burning at high temps. I dont know what the flue temps are, but its not uncommon for Rockland owners to be cruising in the 800's (stove top), just check out the Rockland tips thread. You can load during coaling, but once the fire gets going, its going good. For three years i have kept on eye on the stove, no warping, no glowing, its in perfect shape. Its almost as if this stove is meant to cruise at this temp. Im sure your aware of the florida bungalow column. He mentions adding a baffle at the top, but says it would cause more creosote. I forgot if that was by his own experiment or not. I would think about that, but cleaning my chimney is off limits till the snows gone, so i wouldn't be able to inspect it. Too dangerous in the winter.

 

[Jacklake2003]

I had the same issue with my Napoleon. Mine has one steel draft control plate that opens and closes the primary and secondary openings. In the closed position, there was still quite a bit of gap (opening) remaining. I fabricated a new steel plate out of stock material from Home Depot and reduced the inlet opening by about 50% when the draft is fully closed. It took me 5 years to figure this out, but what a difference; a whole new stove! I use literally half the wood (if not less), get consistent overnight burns, and no longer get the "pucker factor" from runaway fires.

 

[tfdchief]

Like BG, I am not suggesting you do this, but wonder if anyone has ever tried putting a reducer on the top of the chimney. It would be easy to remove for cleaning. I don't know if it would work or not......reducing down at the top end of the flue might not work. Anyone tried this?

Edit: Sorry BG, you suggested basically the same thing. When I read it the first time, in my mind, I had your baffle at the bottom. Please disregard my stupid.

 

[begreen]

No problem chief, like minds and all. Creosote accumulation was my concern, but I think I would still try it if the chimney was more accessible. In this cast it doesn't sound like it, so that is out.

elj923, have you tried with both pilot holes blocked? If not, I think that is the next step. If you have, then I would reexamine the primary slider to assess exactly how much air it still lets in. If it is small, then the secondary port is your next option. For that I would try using a flat magnet to partially block the port.

Let us know how you progress here.

 

[mellow]

Not suggesting doing this but it is an idea, this guy put a damper in his flex liner, still waiting to hear how it does for him

http://www.arboristsite.com/firewood-heating-wood-burning-equipment/211009.htm#post3886170

He did have pictures posted but took them down.

 

[EJL923]

That had actually crossed my mind, putting a 4" or 5" damper in the coupling for the flex liner. im sure it would void the UL listing of the liner.

 

[EJL923]

BG, what do you know about stoves with the IR coated glass? Seeing as how my stove runs so hot, i was thinking about replacing the special IR coated glass with regular ceramic. More radiant heat from a flush insert would be welcome. I would have to keep an eye on the efficiency of the stove, but i just dont see that being a problem.

 

[Savaneiro]

EJL923, long time lurker, first time poster. I have a similar issue with my C550. I can't burn a full load without hitting 950F. My chimney is 25ft on a outside wall and partially in my uninsulated garage. Why did you decide to go with the damper as opposed to modifying the secondary inlet?

 

[EJL923]

Well, i havent done anything yet, and this discussion is making me teeter again. For one, i didn't want to pull the stove. Second, i figured Jotul spent some time balancing the intakes, so it would be best just to limit the draft on the back end.

 

[Savaneiro]

Well, i havent done anything yet, and this discussion is making me teeter again. For one, i didn't want to pull the stove. Second, i figured Jotul spent some time balancing the intakes, so it would be best just to limit the draft on the back end.

Too bad their balancing causes me to overfire on a full load.
Well, let me tell you, pulling the stove is a royal PITA! I was hoping that you would show us how to tame the beast but I could not wait as I had a small window of opportunity so I pulled it on Saturday and blocked ~30% of the secondary air inlet with a small piece of sheet metal and magnets. I also have three small holes in the dog house and two are blocked with foil. I have yet to burn a full load after the mod. So far, secondaries are lit in the 300s and i have to leave the door open on start up. I can now shut the primary all the way down without smoking and my top temp so far has been ~780F with the stove 3/4 full. It has been cruising at ~750 and I still have coals about 7hours later.
The temps are still to high for my liking. I will try blocking the last zipper hole tonite and see how it goes. I doubt I will be pulling the stove again though. I clean my flue in late December and at the end of the season, so I'll see if I get more or less creosote due to my mods.

 

[wkpoor]

Overdraft issues are something EPA stoves don't deal with easily. And after reading this post I can sure see where an insert would compound the problem. I'm 41' from free standing to top. Even a fully shut primary can't slow it down enough. Any metal type valve will still have enough leak around it. It is normal for me to run with the primary and damper full shut and I am considering adding a second damper.

 

[EJL923]

Savaneiro, im guessing you bought your stove in the last year or two. Jotul has played around with this stove quite a bit, I think they've added a fourth secondary tube, ceramic blanket on top of the cast iron baffles, and from what you've said, a third doghouse hole. My stove has none of those, and i only bought it three years ago. I have two doghouse holes, with one currently blocked. A simple way to block those is with a machine screw. It doesn't even need to thread, it will just sit there and block the rocket boosters. Its easy to take out between loads to, keep some needle nose nearby, preferable with the grip already gone! Im glad to see youve tried blocking the secondary, gives me a starting point. Im actually stripping the stove dry to lighten the load.

 

[Savaneiro]

EJL923, I bought my stove in 2010. I only have three tubes and no ceramic blanket above the baffles. As for the doghouse holes, there is a large hole in the center and a smaller hole angled at about 45degrees on both sides of the center hole. I'll look into getting some screws to block the holes. I already have the needle nose pliers and a small mirror to adjust my foils.

I blocked the final hole last night and did a burn. The stove was cold and I guess I had too much wood in it as it took over and hour to come up to temp and this is with the door open. With the last hole blocked, I have to keep the primary air a little below half way open or the fire dies out and I get smoke out the chimney. The max temps were about the same, just shy of 800F and it still cruised at 750F. I started that fire at 3/4 full at 9pm last night and got it set at about 10:30pm. I was surprised to find the stove at 250F at 6am this morning. I few coals remained but not enough for a start without kindling. After reload, I was up and cruising at 750F in half an hour. Its not perfect, but a definite improvement. I may consider adjusting the primary air after playing with my current set up for a while.

 

[EJL923]

With my two doghouse holes blocked, i find i get a lot of coaling. Coaling isn't all that beneficial in an insert, doesnt keep the blown air hot enough, at least in my experience. The doghouse, or zipper, holes are needed to help get a burn going in this stove. Because you can really only load it east/west, air doesn't have anywhere to go.

I havent even started to burn yet, so i have no experimental numbers from this year, but i will starting this weekend. Ive been waiting to burn till i do my adjustment so i dont have to deal with soot in the liner.

 

[Savaneiro]

wkpoor, what kind of stove to temps do you see on a full load? What about burn time?

EJL923, I did some air sealing, added attic insulation and changed out a leaky front door this year. Even though the fire is long out, the house holds temp long enough for the coals to burn down, at least for the time being. I hope it continues to do so when it is 15F out

 

[OhioBurner©]

Well I get online after not showing up here much since spring and a thread about a 550 running to hard is one of the first I see! Its hard to keep mine much under 800 with a full load of good seasoned hardwood. I didnt know about any modification to the slider though. I've got about 24' of duraliner in my internal masonary chimney. I plugged both my zipper holes, havent noticed it any harder to start, and feel like I have better coals the next morning. It'd be nice to get some longer burns, this thing just runs like a raked ape!

 

[Savaneiro]

OhioBurner, I feel your pain. IIRC you were trying some longer splits to increase burn times. I take it your not having much success. I have about a cord of 20in splits that are on the large side(7-8in across) that I will be trying later this winter. My hope is to increase burn time and reduce peak temps.