Stoker Stove Output VRS. Hand Fired Stove Output

franco b wrote:

Rob R. wrote:The Hitzer 50-93 seems to be a real solid performer.

Yes it is but I can't picture stuffing 200 pounds in it to achieve a 100,000 BTU rating.

Me either, maybe 60-70% of that if conditions were right. I didn't think of the amount of coal required to actually hit that figure when I made my previous post. I used to have a Hitzer 82 also, I think the most I ever put through that in 24 hours was 120 lbs...and that was with the dial maxed out.

oliver power wrote:Where as a hand fired stove, it can be pushed over it's rated BTU's/hr.

I doubt any modern hand-fired or stoker stove can be pushed over the advertised rating, most of them can't achieve it in the first place. I suppose that some are better than others. Some stoker stoves are rated based on "input" of coal to be burned, and that is also misleading in my opinion.

I have run a hand fired and a stoker. I prefer the hand fired because it's well,,, hand fired. I don't have any hobbies and the hand fired is pretty much it. Yeah I know.....

Anyway as a minister my hours can be very erratic. When I ran the hand fired before I would set it up and plan on being back sometime in the next 8 hours. An "emergency" would come up that delayed me anywhere from 4-6 hours and I would come home to cold iron. I gave it away and got a LL Econo 1 stoker as a scrap yard rescue. I rebuilt it and fired it up. I knew that I could go at least 24 hours on a full hopper with no problem. That was one hassle in my life that kinda took care of itself, simply by changing stoves. It kept us warm. I had to watch coal quality closely and amount of fines. It was a boring stove to run!!! Put coal in take ash out.

With more study and reading I settled on the hand fired VC2310. It is rated at 20K BTU's less than the stoker but my schedule has evened out a lot more. I can set up the Vig and if I have any inkling that I'm going to have a "bad" day I can dial it back a bit and it will go 14-16 hours without a hiccup. I can push it over it's RECOMMENDED limit if I stay right with it. There was no way to get more out of the stoker. You adjusted the stroke until you had burning coals were falling off the grate and that was it. With the hand fed I can burn just about anything that will have BTU value. Fines, no problem just don't coat the entire bed with them. Wood, no problem, Bit coal no problem.

With the Vig, my available fuel range is huge. Both stoker and hand fed do the job. You have to weigh out the druthers.

The original post seemed to indicate that hand-fed stoves had a more conservative rating than stoker stoves. The convenience of one vs. the other could be an entirely different discussion.

blrman07 wrote: I can push it over it's RECOMMENDED limit if I stay right with it.

How much coal per hour does your VC2310 burn when it is "over the limit"?

I haven't measured the amount of coal used like many others on here calculate. I calculate by is Momma warm and happy? Normally I will use about 40 # a day if it's not stupid cold out. I watch the temperature of the stove as measured on the griddle. I normally run between 500-600F. I assume that most any stove rating is based on exactly measured coal quantity along with exactly known BTU rating under lab conditions. Lab conditions nobody has no matter how close they try to monitor their equipment.

I assume that just about any stove is no more than 80% efficient at best. You have to waste some heat to establish draft and without doing that no draft is experienced. My stove is rated at 50K. If I assume that is the correct rating and the 80% rule of thumb applies then the most I should be able to get is 40K. If I am normally running 40# a day then I am somewhere around 21K per hour. Since I know that my stove is not running at 80% and more likely at 60% based on real world usage my max should be around 30K which from experience tells me it's closer to reality.

When I am burning hard I will use around 70# a day which puts me at around 36k per hour. Reality tells me that I can stuff more coal in a hand fired where I can only feed so much through a stoker. Anything is possible but is it likely that you can over fire a stoker like you can over fire a hand fed. Leave the ash door open on a stoker and nothing happens. Leave it open on a hand fed and what do you get.

blrman07 wrote:I haven't measured the amount of coal used like many others on here calculate.

I know you often mock the folks that keep detailed records, but I wasn't asking for ounces per hour, two 5 gallon pails per day or something like that is close enough.

blrman07 wrote: When I am burning hard I will use around 70# a day which puts me at around 36k per hour

Does VC list the maximum operating temperature in the manual?

Correction. I do not mock anybody. I have commented that for me I do not need to keep such detailed burn records to calculate my coal usage. I asked the question as to why people kept such detailed burn records and received replies ranging from it's a hobby with me to I have to know because I don't want to run out of coal. As I have said before I am within 15 minutes of 5 different breakers so I do not have to calculate my winter usage due to a fear of possibly running out. I recognize that if your hours from your supply or you have a winter surcharge to deal with you may need to calculate down to a gnats whisker how much your going to use.

And yes the manual gives operating ranges. Following copied from VC2310 manual. First their disclaimer about lab conditions....

Vigilant II Coal Stove Model #2310
Coal type.................................Anthracite or bituminous
Coal size........................................................Pea or nut
Maximum heat output...........................50,000 Btu’s/hr*
Maximum area heated...................................2,000sq.ft.
Fuel Capacity..........................................45 lbs. (20 kg)
Fuel Loading..............................................................top
Glass Panel..............................Hi-temperature ceramic
Weight..................................................425 lbs. (212kg)
Flue exit position...........................................Top or rear
Flue exit size................................................6” standard
......................................................................8” optional
*This value can vary depending on how the unit is operated, and the type and moisture content of the fuel used. Figure shown is based on maximum fuel consumption obtained under laboratory conditions and on average efficiencies.
**These values are based on operation in building-code conforming homes under typical winter climate conditions in New England. If your home is of nonstandard construction (e.g. unusually well insulated, not insulated, built under ground, etc.) or if you live in a more severe or more temperate climate, these figures amy not apply. Since so many variables affect performance, consult your Vermont Castings’ Authorized Dealer to determine realistic expectations for your home.

Next is the part of the manual dealing with operating temperatures....

The normal range of operating temperatures is between 400° and 700° F, although temperatures slightly outside of this range may be expected. However, if temperatures go above 700° F for extended periods, decrease the air supply (move the thermostat lever to the right) and slow the fire to avoid overfiring.

Hence recommended max temperature is 700F. I can push past this 700F mark very easily and have done so in the past for short periods of time when I goosed the stove with the ash pan door. Why? To knock an initial chill off the house and then settled it back down to around 500-600F steady burn.

My point was you can goose a hand fired but you can't goose a stoker. You can shovel more coal on the grate by hand but that's about it. They both have their pro's and con's.

blrman07 wrote:Correction. I do not mock anybody.

I guess it is a matter of perception.

blrman07 wrote: My point was you can goose a hand fired but you can't goose a stoker.

It depends on the stoker. The bigger Keystokers for example have quite a bit of adjustment beyond what the factory uses to give them a BTU rating. My neighbor has a KC-10 that was struggling with demand at the factory recommended settings...a bump in the feed adjustment cured that.

When you adjust a stoker to max stroke and you have burning coals falling off the grate, then what do you do to goose the fire?

blrman07 wrote:My point was you can goose a hand fired but you can't goose a stoker.

I found out last night while making some adjustments I could 'goose' the stoker to run at about 700* by adjusting the air baffle on the combustion fan. My firebox vs. flue pipe draft reading indicated I may have been able to give even a little more combustion air too.

I didn't leave it there but closed it slightly so its max is about 100* less than that when it runs flat out as it has been this past week.

Rob R. wrote:The original post seemed to indicate that hand-fed stoves had a more conservative rating than stoker stoves. The convenience of one vs. the other could be an entirely different discussion.

blrman07 wrote: I can push it over it's RECOMMENDED limit if I stay right with it.

How much coal per hour does your VC2310 burn when it is "over the limit"?

Exactly Rob R, A consumer, looking to buy a STOVE rated at 100,000 BTU (stoker or hand fired), would assume they'd put out around the same amount of heat. I recently had first hand experience comparing the KETSTOKER 105 (stoker stove), and the HITZER 50-93 (Hand Fired). Both very good stoves. Both in old farm houses. Both rated about the same. Both put out a lot of heat. However, the KEYSTOKER was running flat out. One could get no more performance from the KEYSTOKER. The HITZER was cranking away as usual. The heat coming off the 50-93 was way more intense. And I know the 50-93 can be pushed further if needed. Just one new observation of Hand Fired VRS. Stoker I had not given much thought about. Oliver

blrman07 wrote:When you adjust a stoker to max stroke and you have burning coals falling off the grate, then what do you do to goose the fire?

You adjust the flux capacitor to get more air.

j/k...you are right, once you have maxed out the air and adjusted feed to get burning coal on the entire grate, there is nothing else you can do.

In my example of the KC-10, there was still a long ways to go with the air and fire size.

I wish coal appliances had something like an IBR rating on boilers...a rating you could "take to the bank".

Rob R. wrote:The original post seemed to indicate that hand-fed stoves had a more conservative rating than stoker stoves. The convenience of one vs. the other could be an entirely different discussion.

blrman07 wrote: I can push it over it's RECOMMENDED limit if I stay right with it.

How much coal per hour does your VC2310 burn when it is "over the limit"?

Rob, I'll venture an answer about my Vig-II experience. With Superior nut that I had about 5-6 years ago, I got about 80+ lbs through it. That was pushing it and basing the coal weight fed on 2 heaped 5 gallon buckets loaded in 24 hrs starting the tally with a very full firebox.

The Vigilant II 2310 is designed to operate at 700°F measured on the griddle and is rated, as Larry stated, at 50K BTU/hr. I normally run my Vig-II at 700°F max on the griddle all winter long. Normally I'll feed ~ 50-60 lbs of nut/24hrs. I don't move the thermostatically controlled primary air setting daily, I leave it set for 'cold winter', 'not so cold winter', and might bump it a smidge to reach my target temperaures After a new load and while the entire batch isn't glowing max-red, the reading will be 600-650°F for a few hours. After several hrs (3+) it will settle in on 700 +/- 10°f for the entire burn time of 14+ hrs without ending up with a thin fire. The grates must be kept clear enough to not choke off areas of the grate. That's a matter of knowing how the coal ash forms and the skill to clear it as evenly as possible without wasting unburnt coal. I've learned to read the red glow on the bottom surface of the ash drop.

IMHO, you can push a hand fed beyond it's design if you have excess draft that can provide extra combustion air and if an adequate heat exchange area was designed into the stove. A stoker is limited by force-supplied combustion air design and designed mechanical coal feed/combustion rate. A hand fed is rated at "X" inches of draft but you can exceed that and gain a little more coal combustion if the stove can pull the heat out of the combustion gases before they go up the chimney. All this is installation specific: Your max chimney draft may be different. The Vig-II is small but has a large heat exchange area and a design that creates air turbulence across the heat exchange surfaces. By design, the Vig-II does this without a fan and the stove regulates the amount of combustion air relative to the amount of heat washing off the stove's surface. Stoker stoves/furnaces do this by means of the circulating fan's CFM capacity to move the heat off the heat exchanger and the temperature of the make up air. Boilers use water temperature and storage volume. I don't have a lot of experiences with coal fired boiler or furnaces so those statements are probably really simplistic.