Wild secondary burn control options

[burninwood]

Hi Folks,

Just thought I would introduce myself to the community - been cruising the forum for years but this will be my first post. Tons of great content on here so keep up the good work.

I've been having issues with absolutely nuclear secondary combustion in my PE Vista. This is a main floor install, story and half house, stove in centre of home and roughly 23-24' of chimney (all of which would be interior to the house - aside from 3-4' where it exits on roof).

I have ruled out stove leaks, replaced door/windows gaskets, sealed the ash dump and installed a damper about 24" up in the double wall connector. The damper helps, but no matter what, once I close down the primary, the secondaries will eventually go rogue as the draft increases and the stove warms up. This isn't a matter of me cutting the air too late - I can shut it down when the fire is burning quite poorly, with flue temps around 250 f, but the secondaries will eventually take over and go nuts. No lazy flames here, just the depths of hell roaring out of the baffles with flue temps into 600+...chews wood.

There is no secondary intake control/linkage off of the primary. I believe this design to be different than the Super or Summit stoves (correct me if I'm wrong). So the secondary is always wide open I guess, and once the primary is closed off, the secondary intake tube sucks air in hard which is causing the problem.

Any suggestions on what to do next? Cow magnets? Weld something up and create an adjustment for the secondary intake?

Thanks for any advice! Sorry for the novel.

 

[branchburner]

flue temps into 600+...chews wood.

Welcome aboard! Is that 600f, and measured how/where? How long are the burn times, and what does the stove top temp hit? How old is the stove, and has it always behaved this way?

Most stoves have unrestricted secondary air, but in the past I've put foil over the opening to restrict it (the suction would actually hold the foil in place). With that stove, I still experienced hotter and shorter burn times with less air, and no coals remained at the end of the burn cycle (and I also installed a pipe damper to slow it down).... so I'm pretty sure it leaked somewhere, but I never located the problem. How did you rule out a leak... with a smoke test?

 

[Hubby with a C]

Welcome to the forum. It seems like you have excessive draft. Probably the best thing to do would be to install a stovepipe damper. This would give you control over how much are the chimney draws through the secondary air system after you have closed the primary air. In the mean time you may want to try closing the primary air a little sooner. A slightly cooler chimney may not draw as hard.

 

[Smoked]

Yep, I have liked the extra control the pipe damper gives me. If that is an insert, someone on here last year posted a thread where they connected a rod to a key damper so they could control it through the front cover. Before last year, I controlled mine with the load. Very large splits take longer to break into nuclear mode

 

[begreen]

Already has a pipe damper. Burning thicker splits is an option.

 

[Smoked]

Totally glassed over the damper part...duhhhh Maybe someone needs to make a tighter damper. OAK with a ball valve on the intake side??? I was thinking about that but the damper got me what I needed.

 

[huauqui]

burninwood,

great first post, welcome! I had a summit series A in my basement until last Saturday. I removed it because of the same things you mentioned in this post. I simply was not able to keep the secondaries under control and for me it meant way to high of stove pipe temps. The two things, besides the chimney damper that helped me were 1. I sealed the air intake for the ebt completely shut so it could no longer add air to the firebox. 2. a magnetic strip covering half of the air intake on the lower back of the stove (not the round hole on the back of the pedestal but the actual rectangular hole that runs up the back of the stove feeding everything.

Having to modify it to be safe made me remove it. My insurance would have balked if I had ever had a fire.

I will write a full post on my experience soon but I did all the things you listed as well to no avail.

Hope you find a good solution,

huauqui

 

[BenTN]

do you have an OAK (outside air kit)? does the stove have an option for an OAK? they make an inline damper with remote control for 3-5" fresh air kits. might help control the total intake air both primary and secondary.

 

[burninwood]

Hi Guys,

Thanks for all the suggestions and tips - didn't expect to get so many replies!

I'll try to answer all the inquiries in one post here, rather than doing a bunch of inline quoting.

• All temps quoted are in degrees Fahrenheit measured with a flue probe thermometer about 19" from top of stove top
• No stove top temps as it is a Classic model (freestanding, not insert) with the enameled steel 'floating' casing around the stove - not sure if readings would be accurate off of the decorative casing
• I can get max 4 hr burn times - mainly burning ash, sugar maple, ironwood...basically all hardwood in my last load of logs
• Stove has always behaved this way (since my wife and I moved into the new place a few years ago)
• It is a model B Vista I think - pretty sure it was installed around 2007-2008
• I checked for leaks with a smoke test
• I did install a damper (ICC UBD section...don't get me started on the price...should have bought the $8 one from Home Hardware)
• It will eventually go crazy with both large or small splits...larger splits definitely take longer to go nuclear but they will eventually
• I can cut air when temps are around 250 f and fire is burning poorly - will still draft really hard eventually as it heats
• I don't have an OAK - it would be pretty tough to do given where the stove sits in house

As a test late last night I put on a leather glove, reached in underneath and stuffed my hand up to block the primary intake - the secondaries get worse. I then reached to the secondary intake and blocked it off about 75% with the glove and I was delighted to see the 'magical' lazy secondary burn showcased in those unrealistic youtube videos...I guess this is the problem. Maybe I'll invest in some big flat magnets. Anyone know where one could buy these? Flat cow magnets or something from a co-op or a hardware store?

"huauqui", too bad about your situation with the Summit...I get the whole EPA thing and think the stoves are generally awesome, but I wouldn't buy a car without brakes!

Thanks again

burninwood

 

[begreen]

By restricting the primary air flow, more air is going to be pulled through the secondary air ports. I would say that it did not get worse, it got better. You want robust secondary combustion in the firebox. More secondary burn will usually drop flue temp and increase stove top temp. I sent this in a PM to you this morning. Coincidentally I had a similar situation occur.

Normally our flue temp stays about 100ºF below the stove top temp. Our stop has been bent so that the opening when the air is closed off is about 50% of the factory setting. I usually don't close the air down to the stop. But this morning I did a reload on a nice coal bed and the flue temp shot up to 800F, with the stove top catching up at only 500F. I closed the air all the way down to the stop and the flue dropped to 600F in 5 minutes while the stove top heated up to 650F. In another 5 minutes the stove was running normally at 675F with the flue at 550F. About 30 minutes later I could open up the air a tiny bit (15%?) for normal burning. The flue temp remains about 100F below stove top temp.

Today is quite windy and that plus nice dry wood on a hot coal bed is probably what caused the temporary spike in flue temp.

My suggestion would be to try bending the stop for the primary air so that the air can be reduced further, maybe half the factory stop setting. Then try running the stove a couple days with the decreased stop setting. If flue temps still don't drop then consider a restriction of the secondary air port starting around 50%. A flat magnet should work. Maybe try one of these?
http://www.homedepot.com/p/MASTER-M...PIPHorizontal1_rr-_-203613147-_-203613132-_-N
or
http://www.amazingmagnets.com/show-decimal-q063p.aspx

 

[burninwood]

After reading a similar post regarding a Super 27, I figured I should follow up with this for others' future reference.

Nothing worked until I went out and bought two 3/8 x 7/8 inch magnets from Home Hardware. Blocking off the secondary air intake by half, along with blocking the primary intake just a tad more than the factory stopper would allow, I now have total control of the stove, I get way more heat out of it since I'm not dumping it out the chimney, and I don't churn through would like before. It was suggested that I bend the tab stop for the primary intake so it would close more, however, I wan't comfortable doing this for fear of insurance issues.

One thing I will say is that I required BOTH magnets to make this work. Blocking the primary more with the magnet would make the secondary pull hard...sure it burned clean but it also raised the flue temps because the flames were rushing vigorously out of the baffles and up the flue. Just blocking the secondary (no magnet on primary), still wouldn't slow it down enough for me to get heat from the stove top. One word of warning: When I tried using both magnets on the secondary intake such that the opening was like a quarter of what it should be, the secondaries were burning so slow and so hot that I believe it overfired the stove (I could see stove collar faintly glowing when I turned out lights and the stove was throwing heat like never before). When I reached under and removed them, the stove temps dropped and the flue temp went up.

I see a ton of suggestions on here for turning down the air earlier, or installing dampers. For some, this may work, but in my case (and others, I am sure), these suggestions just did not cut it.

Thanks to all for the replies and suggestions.