Bushel of Ashes Should Weigh...?

How much should a bushel of ashes weigh if burnt properly?

We've all read the posts talking about complete burning, incomplete burning, clinkers, black coal in the ashes, etc.

But wouldn't it be a good measurement to WEIGH a bushel of ashes to determine how much is being burnt/wasted to evaluate the coal quality and combustion settings?

When I get my next ash change, I'll top it off level with the other ash pan and weigh mine. NO PACKING IT DOWN.

Anyone else care to share?

I don't think a specific weight for a specific volume will be very accurate. Some ash is light and fluffy, some is heavy and more powder like mortar mix. IMO, it's best to weigh the ash against the coal used to get a percentage. The "average" ash/coal ratio is about 12% but that varies with coal too so you need to know what the specs are on your coal if you really wanna nail down your efficiency.

Different coal makes different ashes. Harmony ash weighed 22-25 lbs for my #1 square tub. Lehigh is heavier coming in around 30lbs/tub. Hudson was the lightest at around 15-18/tub. The harmony had no unburnt coal. The Lehigh has unburnt coal. The Hudson has no unburnt coal but have to take the tub out x2. Direnzo's ash was heavy also. But with the heavier ash came longer times between emptying. Gales ash was heavy and empty x2. Just my uninformed observations.

Thanks for the quick replies!

I know carbon content and other factors vary between different coals and each burns a little differently.

I realize measuring coal input and BTU output of the boiler is obviously the "best" way to evaluate the efficiency of the coal, your setup- boiler, draft, feed rate, standby running, combustion and idle fans, etc.

But I also realize that is pretty time/effort intensive. Each bucket added should be weighed (or standardized), then tracked over a period of multiple refills. In a hand fired stove I could count the number of shovels used in a given period and be fairly accurate, but my stoker would be more difficult to accurately do this.

Since it seems you can't just weigh the ashes output per volume and use it to determine the BTUs used without a Coal-input measurement, here's another idea I have.

If I am tracking the amount of TIME the stoker part run (feed motor), do you think it would be a steady enough feed rate that I can measure the feed rate, then use that to weigh (pun!) against the weight of the ash tub?

I am waiting on a few very particular components before I can add the arduino measurement and controls to the system. For now I am concentrating on adding inputs and connecting to relays for actions. Initially, they will be connected in parallel to shadow the system and will trigger a dummy load while we work on logging and "stuff"

At some point we'll flip-the-switch and let the arduino handle it all, likely a few items at a time at first.

All that to say I can add the monitor/recording feature to the stoker (feed) motor sooner rather than later and use that to determine the coal used, per ash pan.

It is also going to be warm enough to shut down the boiler and run the stoker for an hour without a fire and weigh the fresh ash pan to see how much coal it feeds in 60 minutes. Think that would be accurate enough to figure out the feed rate to use in my calculations?

Unless you have the option of buying coal from many different sources, I am not sure what you will be able to do with the information.

Your idea of measuring the feed rate is a good one, that way you can track run time with an hour meter and see how it is impacted by other changes to the system/house.

Low ash coal won't help you if you have to burn twice as much to get the job done. Coal that provides a lot of BTU's with an average ash content has been the best for me.

I've thought about this since my last post. Remember the old school way of determining your gas mileage? You start the trip with a topped off gas tank, take the trip and record the miles. Then top off the tank again and look at the pump to see exactly how many gallons it took, which will be exactly the same as what was used for the trip. Now you have the exact fuel usage and miles driven. So lets take this and impose it on a stoker.

Start with an empty ash pan and a full leveled off hopper. Run it for two days, and weigh the ashes. Then with a weighed bucket of coal fill the hopper back up to full and level. Now you have the exact coal used and the exact weight of the ashes. Divide the coal used into the ash weight and you have your accurate ash/coal percentage. I've done this with my hand fed over a series of 7-10 consecutive days and get around 15% ash/coal ratio. Given that my coal is roughly 12% at spec (+ or - a couple %) I can confidently say that my unburned coal that falls thru the grates is somewhere between 2-4% which is pretty respectable given the aggressive ash clearing job it entails.

Rob R. wrote:Unless you have the option of buying coal from many different sources, I am not sure what you will be able to do with the information.

Your idea of measuring the feed rate is a good one, that way you can track run time with an hour meter and see how it is impacted by other changes to the system/house.

Low ash coal won't help you if you have to burn twice as much to get the job done. Coal that provides a lot of BTU's with an average ash content has been the best for me.

I do have a couple of options available, but it's going to be more about tracking the BTUs used in a given configuration of blowers, feed, and of course load configurations.

1. I'll play with some settings once we get the full control of the system, see if the coal fed vs ashes out changes for the better or worse.

2. I'll play with the loads, zone temps, and other things to get efficient use of the BTUs.

It seems prudent to test the burn efficiencies under various conditions, with a known/measurable basis (coal fed vs ash output by weight), which should allow me to determine if my changes are better or worse- and by how much.

It would sure simplify things to know a precise amount of coal fed and the burn efficiency rate of the coal (measured by the coal vs ashes number).

CoalisCoolxWarm wrote:I do have a couple of options available, but it's going to be more about tracking the BTUs used in a given configuration of blowers, feed, and of course load configurations.

In that case, just track hours of stoker run time vs. degree days. The amount of coal going in is the only thing that hits your wallet. The ashes can be a curiosity, but it is possible to have "better looking ash" and burn more coal due to the excess combustion air.

Lightning wrote:I've thought about this since my last post. Remember the old school way of determining your gas mileage? You start the trip with a topped off gas tank, take the trip and record the miles. Then top off the tank again and look at the pump to see exactly how many gallons it took, which will be exactly the same as what was used for the trip. Now you have the exact fuel usage and miles driven. So lets take this and impose it on a stoker.

Start with an empty ash pan and a full leveled off hopper. Run it for two days, and weigh the ashes. Then with a weighed bucket of coal fill the hopper back up to full and level. Now you have the exact coal used and the exact weight of the ashes. Divide the coal used into the ash weight and you have your accurate ash/coal percentage. I've done this with my hand fed over a series of 7-10 consecutive days and get around 15% ash/coal ratio. Given that my coal is roughly 12% at spec (+ or - a couple %) I can confidently say that my unburned coal that falls thru the grates is somewhere between 2-4% which is pretty respectable given the aggressive ash clearing job it entails.

Yes, this was exactly the method I was referencing (and the same gas mileage example), when I talked about the long way of doing things. I've done this with the fuel many times. The best results are spread out over several tanks.

Obviously this would take some time and require diligence if you are the only one filling the hopper.

But I like the stoker feed rate as a one time measurement better. Sure, it does require a shutdown, feeding a bed or two full of coal into the ash pan first, then starting with a new, empty ashpan and running as close to full pan of only coal. But I think it will give me the other part that I was going to determine anyways- how much coal is required for a load and how much is being fed.

I appreciate you giving the question the extra thought

IF all goes well, by the end of this heating season we should have some pretty good numbers to work with and likely ALL parts of the system reading data and possibly being controlled by the arduino.

The end game is to apply "smarts" to it

The Purpose? Mostly to teach my daughter electronics and programming, allowing her to develop these modules and components- with me acting as SME and IV&V (well, not so "independent" LOL)

If we like it and it's practical, I may help her "bring it to market" for a couple of buddies' systems, so she can learn about proof of principle, prototyping, testing and documenting, product development and "marketing" (very limited audience), and presenting it in a manner to "investors."

She can use all this for her school STEM and preparation for college in 2 years.

Hopefully we will end up with a pretty tuned system and learn some things along the way

Rob R. wrote:

CoalisCoolxWarm wrote:I do have a couple of options available, but it's going to be more about tracking the BTUs used in a given configuration of blowers, feed, and of course load configurations.

In that case, just track hours of stoker run time vs. degree days. The amount of coal going in is the only thing that hits your wallet. The ashes can be a curiosity, but it is possible to have "better looking ash" and burn more coal due to the excess combustion air.

Thanks for that, Rob.

Yes, BTUs vs degree days, PLUS factoring in usage/demand per zone. Our usage changes all the time, so have to account for that.

Additionally, I believe that insulation and heat losses are greater factors at lower outside temps.

We hope to work with outside temps, too, much like outdoor resets work.

Sure, we could buy some of these components, but where's the fun in that? LOL. Besides, they don't always work together as we expect or would like

A bushel is about 9.3 gallons. So one could weight quart jar and multiply by 9.3 * 4 for the bushel value .... or otherwise ....

I say we do so, and see what variations are noted .... clinkers, powdery ash, random sampling from your ash ...

Sounds like fun. Maybe include stove burnt in and sized coal and source co. for coal as data to also include

I'll post back with my results ....

Posting back !

My MT container weighed 3.5 oz (postal scale) = 99.2 g

My Ash filled container weighed : 2 lbs 11.0 oz or 27 oz = 765 g --------- (- MT container mass) final mass of just ash = 665.8 g

My water filled container weighed: 6 lbs 3.6 oz or 99.6 oz = 2820 g ----- final wt/mass of just water = 2720.8 g

Assuming density of the water = 1 , then

The bulk density of ash = 665.8 / 2720.8 = 0.245

1 bushel = 35.2 L

bulk density = 0.245 = 0.245 Kg/l

.245 Kg/l * 35.2 l/bushel = 8.62 Kg/bushel

8.62 Kg/bushel * 2.20 lb / Kg = 19.0 lb/bushel

Sample info:

Anthracite nut coal
Hitzer 503
Reading coal

davidmcbeth3 wrote:Posting back !

My MT container weighed 3.5 oz (postal scale) = 99.2 g

My Ash filled container weighed : 2 lbs 11.0 oz or 27 oz = 765 g --------- (- MT container mass) final mass of just ash = 665.8 g

My water filled container weighed: 6 lbs 3.6 oz or 99.6 oz = 2820 g ----- final wt/mass of just water = 2720.8 g

Assuming density of the water = 1 , then

The bulk density of ash = 665.8 / 2720.8 = 0.245

1 bushel = 35.2 L

bulk density = 0.245 = 0.245 Kg/l

.245 Kg/l * 35.2 l/bushel = 8.62 Kg/bushel

8.62 Kg/bushel * 2.20 lb / Kg = 19.0 lb/bushel

Sample info:

Anthracite nut coal
Hitzer 503
Reading coal

Wow, great post!!!

I am planning to do a shutdown later this am. Have a full bushel pan of ashes that I can weigh and will do the stoker feed for 30 mins of only coal without a fire (after clearing the bed with the stoker feed)

I won't be quite as quantitative as you, using water to determine exact volume (impressed!), but my feed rate of lbs/30 mins should get me a pretty good lb/min.

I can then fill an empty ash pan with coal (shovel is faster) and weigh it to compare to the full ash pan weight.

Thinking about running the stoker until the ash pan is full of coal, but then realize the challenge of getting it exactly full, being there to watch and stop it, shaking the pan so it is level, etc. That's where the 30mins test comes in.

Although I didn't see it, I'm sure this is a common test people do to determine their feed rate, right?

The query was " how much does a bushel of ash weigh", right?

Requires all these simple measurements...unless you have an actual bushel hanging around...or a calibrated container wherein the known volume is already known.

I just grabbed an MT food cylinder and used that...easy enough to do.

Only took 3 actual measurements on a scale....rest is all math and computation using my bulbous brain that my wifey says is useless.

davidmcbeth3 wrote:....rest is all math and computation using my bulbous brain that my wifey says is useless.

Oh...so its not just me that has his dearest hold that opinion of him