Oh Great, Another Cracked Grate!

I just went to shake down the stove and the grate locked up. After a quick inspection I noticed the grate was cracked. I just cracked a grate last season and changed my tending in hopes of resolving the problem. Odd...both grates cracked in the same exact spot, right where the primary air comes in. I used to shake the crap out of the grates getting every last bit of ash off of them. After experiencing a cracked grate prematurely I started to ease up on the shaking and leave a bit of ash on the grates. My thinking was that the ash would help insulate the grates from the coal bed. Well, it didn't seem to help as I just cracked another grate. I'm burning in a Coal Chubby and reached out to Larry Trainer hoping for some guidance. All other advice is welcome as I try to straighten this issue out.

I run on a 12 hour tending cycle as most probably do. Here's my routine, maybe there is a flaw in it that I'm missing.
- Open the MPD and primary air 100% and throw a few scoops of coal on. I empty the ash pan from the previous tending.
- After about 10 minutes I close the primary air completely and proceed to shake down the stove.
- After shaking down I fill the fire pot to the top and set the primary air back to 100%.
- After about 15 minutes (blue flames present) I adjust the primary air and MPD to the desired settings.

I be sure not to allow the ash to build up past the lip of the pan. If this happens I empty the ash pan immediately after shaking down the stove. So I can rule out ash in the pan as an issue. I can also rule out over shaking since I still experienced a cracked grate after leaving a bit of ash on the grates. Larry explained to me that by opening up the primary air 100% I'm creating a blast furnace effect on the grate which in turn damages it prematurely. I thought the rush of air would actually help cool the grates. I used to follow his instructions like a bible but experienced long recovery times between tending and was hoping to cut down on the heat loss, so I started cranking open the primary air during tending. He says it's impossible to put that much gas up the 6" flue at once. My house is poorly insulated and in the heart of winter it's hard making up for the heat loss we experience. Back to square one, follow Larry's advice!

Tcalo,

I just sent you a PM.

dj

Was that a new grate after the last one cracked? New cast grates should be seasoned. There are two ways to do it. First put a new grate in the oven at 325. Every 30 minutes increase the oven temp by 25 degrees until the oven is maxed out. Or you can accomplish the same thing by having 5 small kindling fires, allowing the grate to cool between fires. Following these procedures should give you better service life from your grates.

I wouldn't put fresh coal on before shaking. It's just extra weight for the grates to deal with while shaking. Every little bit of weight on top adds a lot of stress to the grates. Shake first then add fresh coal after.

One of the old stove Co. says to build a wood fire and heat up the stove.
Then let it go out and cool down, do this 3 times to season the grates.
I can't remember which Co.

Well since opening up the primary air 100% causes the blast furnace effect as Larry states, I would do your drill but crack the ash pan door and get air spread over a bigger area less stress on a small spot. Your recovery should be about the same if not sooner. I don't have a primary air inlet so us Vigi folks use the ash pan door and viola! Get the 2 brazed and use 'em and keep a new one for emergencies.
Mike.

tcalo wrote:My house is poorly insulated and in the heart of winter it's hard making up for the heat loss we experience. Back to square one, follow Larry's advice!

I think this is 99% of your problem. You are asking this stove to simply do more than what it is intended to do in relation to your situation. You have several options.

1) Tighten up the house

2) Get a bigger stove

3) Add a second stove/furnace

4) A combination of the above.

Hand feds for the most part aren't designed to heat a whole house. They are supplemental heating units. Many of course can and do heat their entire homes with simple hand fed units but it is on a case by case basis. Continue on your quest for a BB and get a big one like a Crawford 40 or Glenwood 8 as it sounds like you need some serious BTU's to keep the house warm.

Follow Larry's advice and instructions. He has forgotten more about coal burning than most of us will ever know.

michaelanthony wrote:Get the 2 brazed and use 'em and keep a new one for emergencies.

Once the grate cracks it swells from the heat and gets stuck. Just a paper weight at this point. I think part of the problem is the design. The grate pivots on a center pin which holds the weight of the coal. I feel this makes the outer edge of the grate susceptible to warping and cracking from the weight of the coal.

I cracked a grate last year and was wondering what to do. I took the remains of the old grate to a steel fabricator and he cut me one out 1/2 inch steel plate. Plasma cutter would be my guess. Amazing how precisely those things cut metal. Worked great with no issues.

Some time back, someone graciously offered to sell me grates for a Glenwood Oak 30. I thought I was all set with the grates I bought from another source but the casting is bad and the handle doesn't fit it well.

If you happen to see this and the grate/grates are still available, I'd be interested.

Thanks, Mark

i have a chubby also. I tend mine basically the same way you do to. except I do not add any coal prior to shaking. I am on my third grate in as many years owning my chubby. my first grate was already in bad shape when I bought my stove. my second grate cracked in the exact same spot as yours. I felt as though I could have taken a grinder to it on the outer circumference and still be able to use it but I replaced it instead. my newest grate I seasoned in the oven. and I also added the ash ring that I also seasoned. I then made several small wood fires over the course of a few weeks during the warmer weather. so far it is holding up well. but I also have not ran the stove as hard as I had to last winter. I live in a old stone house that is not energy efficient at all. last winter was brutal around here, and for quite a while I was averaging 700 degree stove temperatures. we had to tend to the stove 3 times a day at those temperatures. at first I was a little upset about my grate only lasting a year. but after figuring how hard I was running my stove, and how much I saved on fuel oil, that money spent on the grate really didn't bother me as much. one of the things I have been doing for the past few years is that heat shrinking clear plastic you put over your windows. I have over 30 windows in my house. most are newer but 10 of them are very old and drafty. that plastic is cheap and annoying to do but I feel it makes a nice difference.

tmbrddl wrote:I cracked a grate last year and was wondering what to do. I took the remains of the old grate to a steel fabricator and he cut me one out 1/2 inch steel plate. Plasma cutter would be my guess. Amazing how precisely those things cut metal. Worked great with no issues.

i also considered making my own grate out of steel. in fact I am going to keep an eye out for a nice piece I can borrow from work.

Eb426 wrote:i have a chubby also. I tend mine basically the same way you do to. except I do not add any coal prior to shaking. I am on my third grate in as many years owning my chubby. my first grate was already in bad shape when I bought my stove. my second grate cracked in the exact same spot as yours. I felt as though I could have taken a grinder to it on the outer circumference and still be able to use it but I replaced it instead. my newest grate I seasoned in the oven. and I also added the ash ring that I also seasoned. I then made several small wood fires over the course of a few weeks during the warmer weather. so far it is holding up well. but I also have not ran the stove as hard as I had to last winter. I live in a old stone house that is not energy efficient at all. last winter was brutal around here, and for quite a while I was averaging 700 degree stove temperatures. we had to tend to the stove 3 times a day at those temperatures. at first I was a little upset about my grate only lasting a year. but after figuring how hard I was running my stove, and how much I saved on fuel oil, that money spent on the grate really didn't bother me as much. one of the things I have been doing for the past few years is that heat shrinking clear plastic you put over your windows. I have over 30 windows in my house. most are newer but 10 of them are very old and drafty. that plastic is cheap and annoying to do but I feel it makes a nice difference.

tmbrddl wrote:I cracked a grate last year and was wondering what to do. I took the remains of the old grate to a steel fabricator and he cut me one out 1/2 inch steel plate. Plasma cutter would be my guess. Amazing how precisely those things cut metal. Worked great with no issues.

i also considered making my own grate out of steel. in fact I am going to keep an eye out for a nice piece I can borrow from work.

The grates of these stoves are made from ASTM A319 cast iron. That's an excellent material and far surpasses the heat resistant abilities of steel. For both of you guys, I'd highly recommend getting a larger stove. The grates Larry is putting in these Chubbies are top notch. If you run the stove real hot for a long time - you will burn out the grates.

dj

You are probally correct about needing a bigger stove. As I said I ran mine very hard last winter. But 75% of last winter my chubby had no problem keeping my 1st floor at 75 degrees with a stove temperature of 400 degrees. It was only when the outside temperature was at 10f or lower that I had to crank it up to the higher temps. For my situation in my house a stoker boiler would be the better option. Maybe next year.

Eb426 wrote:i have a chubby also. I tend mine basically the same way you do. I am on my third grate in as many years owning my chubby. my second grate cracked in the exact same spot as yours.

I was beginning to think I was the only one with this issue. I haven't heard from any other Chubby owners regarding warped and cracked grates.

dlj wrote:I'd highly recommend getting a larger stove.

Although I'm not arguing the point that I could benefit from a larger stove, I know this isn't the issue. If I was pushing the stove beyond it's capabilities trying to maintain a warm house then I would have to agree. My stove temp is averaging 550-575 degrees in the heart of winter, occasionally tipping into the 600 degree range. Well within the 400-650 degrees operating range stated by Larry.

I think it's safe to say it's not a casting issue since I don't hear of many warped and cracked grate problems for these stoves. It must be operator error! Now I just have to pin-point what I'm doing wrong. I believe Larry is onto something about opening the primary 100% after reloading. I'll follow his recommendations about keeping the primary air chocked down after a reload and see if it helps. I still feel like I'm not leaving enough ash on the grates. After a shake down the grates are glowing red, this can't be good. It's a fine line...too much ash removed and I could run into grate problems, too little ash removed and I run the risk of choking the fire. I've read about others shaking until hot coals start to fall into the ash pan. Different stoves, different techniques I guess!

michaelanthony wrote:Well since opening up the primary air 100% causes the blast furnace effect as Larry states, I would do your drill but crack the ash pan door and get air spread over a bigger area less stress on a small spot. Your recovery should be about the same if not sooner. I don't have a primary air inlet so us Vigi folks use the ash pan door and viola! Get the 2 brazed and use 'em and keep a new one for emergencies.
Mike.

As mike stated here about opening the ash door. I have been doing this for a while. It does get the fire roaring good pretty quick. Plus I think mike is right about spreading the air over a larger area. Thinking of it now and looking at your grates and thinking of my cracked grates. Where those cracks are is the closest spot where the incoming air is coming into under the grates. It's a good possibility it may cause the grates to overheat in that spot.
I have tried brazing my old grates to no avail.
I then tried welding them. Cast iron is a little bit of a challenge to weld. I have done it successfully with proper preheating, proper slooooow cooling. And the correct welding rod. When I tried welding my old grate though I did none of that. And that was the end of that grate.
I still shake my stove down until the red coals are down on the grate. About 40 to 50 pulls on the shaker rod. I then poke up through the bottom to try and remove more ash and make air holes in the burning coal.
So far so good this year with my grate. As I said I took precautions with this one by seasoning it and building several small wood fires then allowing it to cool down. Its still early in the season though. I have my fingers crossed.