Secondary Air for a Crane 404

michaelanthony · Post by **michaelanthony** » Mon. Dec. 15, 2014 10:33 am

windyhill4.2 wrote:Maybe my stove works fine for secondary air because I didn't tighten the glass very much & a little air slips in around the glass ???

right on...we all need a little secondary air.

coalvet · Post by **coalvet** » Mon. Dec. 15, 2014 1:11 pm

I have no baro or mpd on my 404 and it burns fine. I'm not sure why you're having problems with stove regulation or secondary air problems. Maybe you should try the same technique as windy and me since we do ok with the stove as it is with no modifications at all!

ddahlgren · Post by **ddahlgren** » Mon. Dec. 15, 2014 1:38 pm

Problems I have are as follows
Can't get below 375 on stove top though no visible leaks checking with smoke, baro did help a bunch. I am thinking some good fitting steel plates with fire brick on top to cut grate area in spring and fall.

The gates really are not that effective for clearing the red ash I have been getting some powder like and some coarse that block the grates. Had I known this I would have raised the stove more so easier to poke and slice.

Slow to restart after loading unless I crack the loading door but that but I have things to do beyond sitting and waiting with doors open If I close the ash pan door it still builds heat but have to wait to add more coal. With all the talk about puff backs I am very reluctant to just fill and walk away. If I had it to do again I would have left a gap in the corners of window glass on bottom for a little secondary air. I don't want to chance breaking the glass so off the table in my mind.

Does this all make sense?

coalvet · Post by **coalvet** » Mon. Dec. 15, 2014 1:48 pm

I've never had a puffback with mine. Also after reloading a full charge all at once I never open the feed door again until it's time to tend the stove again. Opening the feed door only lengthens the recovery time for the stove.

windyhill4.2 · Post by **windyhill4.2** » Mon. Dec. 15, 2014 1:51 pm

Lower the stove temp by shaking less ash down or buy some pea size coal to mix in to help slow the draft down. With a baro,it should stand wide open during the heavier draft times if the draft is so high. Just yesterday my stove top was under 300* & revived just fine last evening. Coalvet,are you saying that you can just refill the fire pot to the top,not worry about seeing flames, close up & walk away.?

ddahlgren · Post by **ddahlgren** » Mon. Dec. 15, 2014 2:14 pm

windyhill4.2 wrote:Lower the stove temp by shaking less ash down or buy some pea size coal to mix in to help slow the draft down. With a baro,it should stand wide open during the heavier draft times if the draft is so high. Just yesterday my stove top was under 300* & revived just fine last evening. Coalvet,are you saying that you can just refill the fire pot to the top,not worry about seeing flames, close up & walk away.?

The full load and walk away has me curious!

coalvet · Post by **coalvet** » Mon. Dec. 15, 2014 2:16 pm

Yes I do fill it up with one load and then open the ash door and wait in the room of course for the blue ladies to start. On average it usually takes about 15 minutes. After that I close the ash door and I'm done for the next 12 hours. One spinner open about 1/2 turn will give me about 350 to 400 degrees on stove top.

Post by **Lightning** » Mon. Dec. 15, 2014 2:22 pm

Just because he can do that without puff back doesn't mean you can.. Every set up is different. He must have enough air coming in, whether its from over or under the fire to keep the gases diluted until they can ignite safely. I've noticed also that white ash coal has less volatiles. When I was using red ash I got the bajesus scared outta me a few times if I didn't follow the rules..

windyhill4.2 · Post by **windyhill4.2** » Mon. Dec. 15, 2014 2:26 pm

I need both spinners open 1/2 turn for those temps,i do have a baro because of the gusty winds we so often get here. What I have observed with this stove so far is that it seems to get secondary air coming up around the fire pot,may explain why it is not prone to puff backs. ?

coalvet · Post by **coalvet** » Mon. Dec. 15, 2014 2:29 pm

If his 404 needs a baro and an mpd just to control the burn then he has plenty of draft. I have neither and I can literally stop this stove in it's tracks with just my primary air controls.

ddahlgren · Post by **ddahlgren** » Mon. Dec. 15, 2014 2:37 pm

I need them open an 1/8 or less. Before the baro light was easy but going down to 0.03 has made it a lot tougher. At 0.05 of a bit more real easy.

ASHDUMP · Post by **ASHDUMP** » Wed. Dec. 17, 2014 7:45 pm

Can someone explain to me what the secondary air is and why its needed? From what I can tell secondary air is air that does not pass thru and up the bottom of the coal? Air that goes over the coal and out the vent pipe?

why are the dancing blue ladies so important? I get blue flames every once in a while but always maintain a normal temp of 500+. I usually only get the blue flames when the top and ashpan door are open.

Post by **Lightning** » Wed. Dec. 17, 2014 8:15 pm

Secondary air is combustion air that comes in over the fuel bed. It's important for burning volatile gases that are being baked out of the fuel. With anthracite, there is a release of hydrocarbons shortly after a fresh charge is added. This is when it's good to use a fair portion of secondary air.

After the fresh charge gets hot and begins baking out the hydrocarbons, the blue ladies ignite. You can gain some btus if the fire is being given the right amount of secondary air. Once most the hydrocarbons are baked out, secondary air isn't quite as important and usually ends up being a vehicle to carry heat out of the stove. I believe a very small amount of secondary air will help burn some carbon monoxide into carbon dioxide later in the burn cycle too.

windyhill4.2 · Post by **windyhill4.2** » Wed. Dec. 17, 2014 8:17 pm

Secondary air is indeed air that does not come up thru the grates. I think on my 404 the secondary air comes up around the edge of the fire pot,at least it looks that way. I follow the Keep It Sensibly Simple rule & If It Ain;t Broke Why Fix It .I also do not try to figure out how many hours of sunlite my lima beans had by how they taste. I put coal into my 404 after taking the ashes out & it in return rewards us with steady even bone warming heat.I have done as coalvet said,load the coal in wait till flames appear , close the ash door,DONE. I guess that doesn't give you much in the way of technical details,but thats the way my stove & I function.

I think the Crane 404 has the air supply designed into it so we non-thinkers can load & go.

Post by **Lightning** » Wed. Dec. 17, 2014 8:24 pm

I've also found that extra secondary air has a side benefit that helps drafting during warm days/low slow burns with a chimney that doesn't normally cooperate under those conditions..