Rsf Opel 2 secondary air modification

Crocks

Burning Hunk
Nov 5, 2018
109
Camptonville CA
My stove came with secondary air, so I really can't help you there. I haven't even operated a stove without secondary air in the last 18 years.

It really depends on what your definition of a 10-12hr burn is, with my stove after 10hrs I really only have a small shovel scoop of glowing coals left in and amongst the ashes. The bulk of the heat with mine is already released by the 6 hr mark. A lot of stoves with secondary air the size of yours are only quoting 10hr burn times as well, 12 hrs is a pretty big stretch for a non cat stove. A big reason for this is emissions, you need to burn enough fuel to keep the firebox hot enough to continue with the secondary burn. A long smoldering fire isn't good for creosote buildup, efficiency, or particulate emissions. The only way I know how to reliably stretch burn times to 12hrs or more is to buy a catalytic stove built specifically for that purpose.
Yeh my definition of burn time is from reload to reload. Typically I will not reload untill I'm left with a shovel load or two of coals. What degrees to you wait for untill you close the primary air down? Any way you could upload a video of your stove burning?
 

ABMax24

Minister of Fire
Yeh my definition of burn time is from reload to reload. Typically I will not reload untill I'm left with a shovel load or two of coals. What degrees to you wait for untill you close the primary air down? Any way you could upload a video of your stove burning?
Ok so similar reload times to what I get. I go some by flue temps but also by sight, I gradually close down the primary over about 5 minutes, but the point at which my flue probe hits 600F I'm turning the primary down to 25% or less. Part of it is based on my fuel load, I usually only turn mine down all the way when I have a full load of fuel, if its a partial load my stove cruises best at about 10% open on the primary.

I'll try to get you a video, but I'm back off to work for a few hours, maybe tomorrow.
 
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Crocks

Burning Hunk
Nov 5, 2018
109
Camptonville CA
Ok so similar reload times to what I get. I go some by flue temps but also by sight, I gradually close down the primary over about 5 minutes, but the point at which my flue probe hits 600F I'm turning the primary down to 25% or less. Part of it is based on my fuel load, I usually only turn mine down all the way when I have a full load of fuel, if its a partial load my stove cruises best at about 10% open on the primary.

I'll try to get you a video, but I'm back off to work for a few hours, maybe tomorrow.
I wish my stove came with a more rigid primary air control. Right now if I try to set say at 10 percent it will draft hard enough to actually pull the plate closed. When I go to open it I can actually feel the suction from the draft of the stove trying to hold it closed . It also has a big mettalic damper built in that keeps you from over firing the stove if you forgot to close down the primary control. It's also controlled by a lever to a chain that goes up to the linkage for the damper plate.itself. one day I will install a much better/ rigid design.
 

begreen

Mooderator
Staff member
Nov 18, 2005
85,058
South Puget Sound, WA
Is there a tension spring on the air control valve?
 

ABMax24

Minister of Fire
Here's a low burn from last night, this is 1.5 hrs into the burn with the flue temp at 425F.

As you can see I could probably cut my secondary air a little yet, but I'd rather less emissions over burn time as I live in the city.

 
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ABMax24

Minister of Fire
I burnt about 4.5 cords last winter.

Lol, it gets cold, I'm 450 miles north of the Canada US border, generally we have snow on the ground from the beginning of November to mid April. We usually get -40 every winter and last winter got as cold as -44.

Screenshot (108).png
 

Crocks

Burning Hunk
Nov 5, 2018
109
Camptonville CA
Brrr that is chilly willy!
I wanna move your way to have some real competition on my hands . I blocked half the holes and put in a .516 if washer as a orifice in both ends.

I can't say that the secondary burn is more efficient or better. I can tell you that so far it doesn't seem like the fire can get ahead of itself any more. It seems I can damper down alot sooner at about 300 stove top temp and she slowly climbs up with increasing temps. With a small load it will top out at about 550.

I am overall pretty happy as she sits right now. To give some comparison.

Without secondary air I was getting say 6 hr burn times with the heat never going much over 400. I would also have to wait till I got the temps up over 400 before I could close her down.

Now I easily I get 8-10 hr burns temps over 500.
I find the best thing with the secondary mod is that I can cut the primary air sooner and lower than typical and still maintain a clean hot burn. Then after a few, when the secondarys die off, there isn't a lot of primary air so the coals last a really long time. Still more trial testing to be done overall I am pleased with a warm house.

I owe a huge thanks to all who have gotten me this far and continue to chime in. I appreciate all the feed back guys! Keep on burning on
 

ABMax24

Minister of Fire
Do you have a video of it now? I'm curious to see what it's like at 0.516" orfices. That's pretty small even for 45 holes.
 
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begreen

Mooderator
Staff member
Nov 18, 2005
85,058
South Puget Sound, WA
Here's another one just after the stove was lit, 20% open on the damper, 600F flue temps.

The fire looks good, but that is not just after the stove was lit. All the wood is fully involved and has been burning for awhile. Some is already approaching the coaling stage.
 

ABMax24

Minister of Fire
The fire looks good, but that is not just after the stove was lit. All the wood is fully involved and has been burning for awhile. Some is already approaching the coaling stage.
Half an hour roughly, that's a load of somewhat rotten yet dry spruce, it burns down quick in my stove.
 

Crocks

Burning Hunk
Nov 5, 2018
109
Camptonville CA

.516 orifice/ 45 5/32 holes in reburn tubes. Small load. Closed primary at 400 degrees stove top. This was about 45 mins later at 450. peaked about at 500. No smoke out the stack. Besides relighting I almost never see any smoke out the stack anymore. Been so happy with it I have not messed with anything the last few days. Just waiting in some real cold weather
 
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IowaRSFBurner

Member
Dec 27, 2017
30
Pella, Iowa
I think that burn looks pretty good. Here is a video of my catalytic unit burning some ash.

 
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ABMax24

Minister of Fire
I think it looks pretty good it's getting secondary combustion.

Personally I like to fiddle with these things lots, I'd be sizing up that orfice just to see what it does.

Another thing I'd be attempted to try is to drill 10 or so 1/8" holes in the large 1.5" tube pointing toward the glass. On my tube stove I use the front most tube as an indicator of how well the secondary burn is working. If I have consistent flames coming off of those holes as the gases go around the baffle I know I'm not getting enough air on the back 3, if the flames are intermittent or not affected by the addition of extra air I know I'm getting enough on the back 3 tubes.

It just depends on how much you want to experiment. It looks like you are most of the way there with what you already have, it probably burns cleaner than it ever did in stock form too, and if your satisfied with the burn times and heat output then just leave it.
 
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Crocks

Burning Hunk
Nov 5, 2018
109
Camptonville CA
I think it looks pretty good it's getting secondary combustion.

Personally I like to fiddle with these things lots, I'd be sizing up that orfice just to see what it does.

Another thing I'd be attempted to try is to drill 10 or so 1/8" holes in the large 1.5" tube pointing toward the glass. On my tube stove I use the front most tube as an indicator of how well the secondary burn is working. If I have consistent flames coming off of those holes as the gases go around the baffle I know I'm not getting enough air on the back 3, if the flames are intermittent or not affected by the addition of extra air I know I'm getting enough on the back 3 tubes.

It just depends on how much you want to experiment. It looks like you are most of the way there with what you already have, it probably burns cleaner than it ever did in stock form too, and if your satisfied with the burn times and heat output then just leave it.
I feel that adding holes on my front main tube would really rob from my 9/16 tubes that need all the air they can get. My setup is backwards from most, my secondary inlet is on the front of my stove .

Another thing I was thinking. Depending on draft. The Ideal oridice size probably ranges alot. My stove is hooked up to about 16' of 8" . Very strong draft. My stove is only designed to run 7"
 
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ABMax24

Minister of Fire
I feel that adding holes on my front main tube would really rob from my 9/16 tubes that need all the air they can get. My setup is backwards from most, my secondary inlet is on the front of my stove .

Another thing I was thinking. Depending on draft. The Ideal oridice size probably ranges alot. My stove is hooked up to about 16' of 8" . Very strong draft. My stove is only designed to run 7"
I really don't believe it would, that main trunk tube has more airflow capacity than your 4 9/16" tubes have combined. You would just need to upsize the orfice slightly.

Your thinking on orfice sizes varying is correct in my experience. Mine is set to a happy medium, in warm temps (about freezing) I'm probably a little shy on secondary air, in -40 I have a bit too much. at about -15 (which is average most of the winter) it's about perfect. But I'm okay with extra air at low temps, I can use the extra heat in the house anyway. But I also have 36' of vertical height on 6" chimney from my stove top to chimney cap, so I'm an extreme case compared to most.

I'm also not a believer that an 8" chimney has more draft than a 7", unless you are pushing high flow rates through that chimney. On low setting your stove won't know the difference between the 2. Draft is predominantly a function of flue temperature and height. Which is a reason why stove runaways become a problem, it's really hard to slow a stove down as flue temps increase. More heat in the stove means higher flue temps, which creates a stronger draft, which pulls more air into the stove, which creates a more intense flame, which creates more flue heat, which creates a stronger draft, and so on. Until something breaks the cycle, which in most cases is the stove begins to run out of fuel, assuming the stove is already on it's lowest setting. Which is the primary reason of my secondary modifications.
 
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jjfmetal

Member
Apr 5, 2010
59
Northwest Arkansas
I think that burn looks pretty good. Here is a video of my catalytic unit burning some ash.

looks good IowaRSFBurner ! I have the Original opel 2000, I would love to see some pictures of that catalytic when she cools down. They use to sell the Cat kit for the Opel2000 but its now discontinued. Would love to see how yours is installed, It looks like they kept alot of the original design on your Opel 3. Thanks!
 
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jjfmetal

Member
Apr 5, 2010
59
Northwest Arkansas
I think it looks pretty good it's getting secondary combustion.

Personally I like to fiddle with these things lots, I'd be sizing up that orfice just to see what it does.

Another thing I'd be attempted to try is to drill 10 or so 1/8" holes in the large 1.5" tube pointing toward the glass. On my tube stove I use the front most tube as an indicator of how well the secondary burn is working. If I have consistent flames coming off of those holes as the gases go around the baffle I know I'm not getting enough air on the back 3, if the flames are intermittent or not affected by the addition of extra air I know I'm getting enough on the back 3 tubes.

It just depends on how much you want to experiment. It looks like you are most of the way there with what you already have, it probably burns cleaner than it ever did in stock form too, and if your satisfied with the burn times and heat output then just leave it.
Hey ABMax24 thanks for all the info very helpful! So i have the same fireplace as Crocks and im currently building a similar setup to his. Our Air wash comes down above the glass and my question is do you think by drilling the 1/8'' holes in the bigger Tube pointing toward the glass would effect the way the air wash works in a negative way? Thank you!