LL110 coal usage

I'm not sure if I was expecting a different result, but my coal usage seems high. I burned 440 lbs this week, and 360 lbs last week and last week was colder. I've burned a little over 3,000 lbs from the middle of October. I burned about 600 gallons of oil last year, so I was expecting to only burn about 3- 3 1/2 tons per year. I burned 1,480 lbs for December and 880 lbs for November. At this rate I'll be past 3 tons in February. Are my calculations and or my assumptions wrong, or do I need to look at the boiler a little closer?

Is your heating load the same as before? Same # of people in house, same indoor temperature, same amount of heated area?

Have you cleaned the boiler since firing it up?

I went through 1,130 lbs. in November, and 1,492 lbs. in December, so it appears we are burning at somewhat similar overall rates. Since October 14th I've used 3,312 lbs. of anthracite.

Have you noticed (as I have) that your December efficiency was much better than your November efficiency, and leagues better than your October efficiency? I burned a bit more than 38 lbs. per day in October, a bit less than 38 lbs. per day in November, and a tad over 48 lbs. per day in December.

Are you also heating all of your homes hot water with coal, and did you factor this into your anticipated usage calculations? If you are heating the homes water with coal you are probably using about 5 lbs. per day of coal on average to provide for your homes hot water. About 1,000 lbs. of coal for the heating season should be fair guess for your DHW demand.

Allowing for various factors such as coals inherent water content and a boilers nominal efficiency, I believe its best to assume that in the end you should realize quite close to 10,000 BTU's of actual output from each pound of coal that you add to your boiler. If you used 600 gallons of oil for home heating only, and your oil furnace is 85% efficient. then putting it all together I get:

600 gal. x 138,600 BTU's/gal. x 85% eff. = 70,686,000 BTU's
70,686,000 BTU's/ 10,000 BTU's per lb. of coal = ~7,069 lbs (3.5 tons) of coal required for heat only
Add to this roughly 1,000 lbs. of coal required for hot water and you should have a projected need for a tad more than 4 tons of coal for the season.

Have you also considered that unlike conventional fuels, coal fires must never go out, so in the warmer days and/or months there is some level of inherent waste of coal simply because you will need to burn 'X' pounds of coal per day merely to keep the fire alive, whether your home or homes DHW will utilize it or not. For example, if on a particular day you need the BTU's from only 10 lbs. of coal, but you need to burn 25-30 lbs per day just to keep the fire lit, then on that day your coal loss is 15-20 lbs.

In October my dump zone was set to my garage. By some time in early November I had changed it to the basement. Next season I may change it again, to my living room, dining room, and kitchen loop. I was merely throwing heat to the wind when my dump zone was my garage loop. I also raised my dump temperature by 10 degrees in early November.

Between needing to keep my fire alive and dumping heat to my garage, I wasted a bunch of coal in October that I did not initially anticipate wasting.

Is a baro installed on the stovepipe? Do you have a thermometer on it?

Rob R. wrote:Is your heating load the same as before? Same # of people in house, same indoor temperature, same amount of heated area?

Have you cleaned the boiler since firing it up?

My heating load hasnt changed, actually my house is a little tighter than last year ( attic insulation), and my wife has the t-stats locked down at 68
My DHW should be a little more efficiant, as I've added a DHW storage tank to the tankless coil.

As far as cleaning, I Vacuun out the tubes every Sunday morning. Last week I had an outfire due to "I'll fill the hopper in the morning", and I gave the boiler a thurough cleaning.

coaledsweat wrote:Is a baro installed on the stovepipe? Do you have a thermometer on it?

Baro, yes thermometer, no.

I do hold a steady .04 draft.

Can you touch the stovepipe at idle and if so how long?

lsayre wrote:I went through 1,130 lbs. in November, and 1,492 lbs. in December, so it appears we are burning at somewhat similar overall rates. Since October 14th I've used 3,312 lbs. of anthracite.

Have you noticed (as I have) that your December efficiency was much better than your November efficiency, and leagues better than your October efficiency? I burned a bit more than 38 lbs. per day in October, a bit less than 38 lbs. per day in November, and a tad over 48 lbs. per day in December.

Are you also heating all of your homes hot water with coal, and did you factor this into your anticipated usage calculations? If you are heating the homes water with coal you are probably using about 5 lbs. per day of coal on average to provide for your homes hot water. About 1,000 lbs. of coal for the heating season should be fair guess for your DHW demand.

Allowing for various factors such as coals inherent water content and a boilers nominal efficiency, I believe its best to assume that in the end you should realize quite close to 10,000 BTU's of actual output from each pound of coal that you add to your boiler. If you used 600 gallons of oil for home heating only, and your oil furnace is 85% efficient. then putting it all together I get:

600 gal. x 138,600 BTU's/gal. x 85% eff. = 70,686,000 BTU's
70,686,000 BTU's/ 10,000 BTU's per lb. of coal = ~7,069 lbs (3.5 tons) of coal required for heat only
Add to this roughly 1,000 lbs. of coal required for hot water and you should have a projected need for a tad more than 4 tons of coal for the season.

Well, at least my math isn't off! Your calculations are what I came up with. My old oil boiler was 84% on a good day. I used the old boiler's tankless coil for DHW last year so the load shoould be the same. When I installed the LL110, I added a storage tank to its tankless. I think a nice Weil McLain indirect may be in my future, and Ill use the storage tank as a summer dump zone....

However, the way my DHW works, it never calls in the low limit to satisfy recovery?

plumber wrote:My DHW should be a little more efficient, as I've added a DHW storage tank to the tankless coil.

Splitting hairs here, but with the small but real heat loss of an insulated storage tank, wouldn't that make your DHW a bit less efficient?

coaledsweat wrote:Can you touch the stovepipe at idle and if so how long?

At idle, its almost cool. My c/o door at the top of the boiler is warm ( 180-200 ish?), the flue is about (WAG here) 150-160 before the baro.

Doesn't look like it's going up the chimney. Are you running the house warmer now than with oil? That cost in your mind might have moved the comfort zone up.

coaledsweat wrote:Doesn't look like it's going up the chimney. Are you running the house warmer now than with oil? That cost in your mind might have moved the comfort zone up.

Nope, t-stats are kept at 68, that's the temperature my wife says I'm comfortable at.

The funny thing is I'm burning more coal on 40 degree days than 25 degree days, that's why I'm scratching my head.

On warm days are you seeing a lot of partially burned to unburned coal in the with the ashes?

Not getting unburned coal in the ashes. Although, I'm wondering if the high consumption on warmer days have something to do with my dump zone? I just came from downstairs, and my dump zone radiator was cranking hot! I believe the worst part of the LL110 is its best part. It's too efficient.