Something to ponder for the 'whole house' stoker gang

Re: Something to ponder for the 'whole house' stoker gang

PostBy: Rob R. On: Fri Jul 11, 2014 10:58 am

samhill wrote:As I said Rob, my first statement was meant to be light hearted but I guess that wasn't plain enough. It's easy for me to know that my investment has paid for itself rather quickly as my main source of heat was propain before I went to coal. Now if I had a setup similar to you I might just make a spread sheet, nah I have to be honest I'd just sit there, enjoy the heat & the cold beer. Being less young & even being on a limited income I find that many things in life just don't matter all that much while others matter all the more so I tend to be thankful for what I have & enjoy the time left. :D


my list of things that matter has shortened considerably since I became a dad of two boys. I barely have time to enjoy a cup of coffee in the morning let alone measure how much coal I have burned. I hate to admit it, but I totally forgot to check the ash tub in my EFM last week and it overflowed by an impressive amount. I guess that means things are running good if you can forget that the boiler is even running.
Rob R.
 
Stoker Coal Boiler: EFM DF520
Hand Fed Coal Stove: Hitzer 50-93
Other Heating: Dad's 1953 EFM Highboy

Re: Something to ponder for the 'whole house' stoker gang

PostBy: lsayre On: Fri Jul 11, 2014 11:10 am

Pacowy wrote:
lsayre wrote:After the HVAC guys calculate a homes heat loss, how much padding factor do they (or better, should they) apply above that level in order to size a furnace or boiler?


The "HVAC guys" I would listen to are the ones who use the heat loss computations to check/ensure the adequacy of the installed radiation, and then size the boiler so that it is adequate to power that radiation. Failure to do so opens the door to a world of performance problems that are most evident in steam systems, but - as shown in various forum threads last winter - also can be troubling in hydronic systems.

The heat delivered by the installed radiation needs to be scaled up by a "pick-up" factor to account for distribution line losses when setting the output requirement for the appliance. Pick-up factors are somewhat arbitrary, and vary quite a bit. In the olden days, numbers in the 1.3-1.4 range were often used. Nowadays, the "net" (of pick-up) boiler ratings of some manufacturers differ from their gross output ratings by less than 1.2.

Mike


Thanks Mike! I was initially thinking along the lines of 25%, or 1.25. I agree that 1.3 to 1.4 is probably a good padding factor range to use for coal (due to its characteristics, primarily what I naively have called lag), and for my home that would mean that with a heat loss of around 44,000 BTU's, a coal boiler that is rated to deliver a reliable output of about 60,000 BTU's should suffice for my homes heat, but then I believe that I would still need some extra padding applied on top of that for DHW. Since my AHS S130 Coal Gun only ran (on and off in response to T-Stat calls) about 1/2 of the time throughout the single day when it hit -17 degrees here, I could probably have gotten by with a somewhat smaller and less expensive boiler. Perhaps AHS will consider making an S90 Coal Gun at some juncture?
lsayre
 
Stoker Coal Boiler: AHS S130 Coal Gun
Coal Size/Type: Anthracite Pea
Other Heating: Resistance Boiler (if I ever get it fixed)

Re: Something to ponder for the 'whole house' stoker gang

PostBy: lsayre On: Sat Jul 12, 2014 8:14 am

Another way to approach determining the "padding factor" hearkens right back to the accurate observation that Pacowy made regarding the limitation of the "rule of 2.5X" as a precise tool to determine a homes heat loss due to its only computing to the mean coal consumption on the coldest day of the year and not the "peak" coal consumption during the coldest temperature experienced.

I actually have developed two separate rules involving 2.5's. One which says that for every degree of extra heat (either desired or required) to sustain a target temp 2.5% more energy is required. The other which says that you can calculate (estimate) your maximum coal consumed on the coldest day of the season by taking your daily average consumption for the season and multiplying this by 2.5.

For my specific case last year, the coldest day of the year saw a high of +4 degrees, and a low of -17 degrees, for a mean of -6.5 degrees. And as I understand the Pacowy argument, If I burned 110 lbs. to keep my home warm and at a steady (T-Stat set point) temp for a mean of -6.5 (this coming to 4.583 lbs. per hour) , what hourly burn rate would I need to sustain it at the desired T-Stat temp setpoint during the time when it was actually -17 degrees outside.

The difference between -6.5 degrees (the mean temp) and -17 degrees (the actual coldest temp experienced) is 10.5 degrees. If I need to consume 2.5% more energy per degree then 2.5% x 10.5 degrees of difference = 26% more energy was being burned when it was actually -17 degrees outside. Therefore for my case the burn rate for -17 degrees becomes 1.26 x the mean of 4.583 lbs. per hour, or 5.77 lbs. per hour of feed rate required, and my padding factor for this case is 1.26 (which becomes 1.3 when rounded). Therefore 1.3 it is for the ideal "padding factor".

Putting it all together this brings yet a third rule of thumb into play. The actual rule of how to compute your homes heat loss on the cheap becomes 2.5 x the "padding factor" of 1.3 = 3.25X. The "Rule of 3.25X" is born.

The three separate (though linked) rules of thumb to be extracted from all of this are thus:

1) On the coldest day of the year you will burn approximately 2.5 times the average daily fuel (coal, etc...) you burn for the entire heating season. Thus the "Rule of 2.5X"
2) For each degree of additional warmth desired (or required to sustain a T-Stat setting as the outside temperature varies downward) you will consume approximately 2.5% of additional energy. Thus the "Rule of 2.5%"
3) A homes "heat loss" can be approximated by multiplying the average daily fuel (coal, etc...) used for the entire season by 3.25X and then multiplying this amount of fuel consumed by its BTU content, then multiply this by the efficiency of your heating appliance, and finally divide by 24 hours. Thus the "Rule of 3.25X"


Putting it all together for my case:

Since I burned 11,086 lbs of coal from October 1st through May 31st (my T-Stats "on" season), for me this becomes:

Total days of my (T-stats are on) heating season = 243

Average daily usage for the entire season = 11,086 / 243 = 45.6 lbs.

"Rule of 2.5X" ballpark estimate of coal to be burned on the coldest day of the year: 2.5 x 45.6 = 114 lbs (vs. my actual of 110 lbs)

Rule of 3.25X estimate of "home heat loss":
Step 1) 3.25 x 45.6 avg lbs. burned = 148.2 lbs.
Step 2) 148.2 lbs. x 12,150 BTU's/Lb. x 0.80 (my appliances efficiency rating) / 24 (hours) = 60,021 BTUH

And finally, to match home heat loss to the required heating appliance, divide the homes computed "heat loss" by the efficiency of the appliance.

60,000 BTUH (heat loss) / 0.80 (for 80% efficiency) = 75,000 BTUH input required for my homes ideal heating appliance if such were rated at 80% efficiency
Last edited by lsayre on Sat Jul 12, 2014 8:50 am, edited 4 times in total.
lsayre
 
Stoker Coal Boiler: AHS S130 Coal Gun
Coal Size/Type: Anthracite Pea
Other Heating: Resistance Boiler (if I ever get it fixed)

Visit Lehigh Anthracite

Re: Something to ponder for the 'whole house' stoker gang

PostBy: blrman07 On: Sat Jul 12, 2014 8:33 am

When I burned my stoker my rule of thumb was a 5 gallon joint compound bucket a day if it was cold, 1/2 a bucket when it wasn't in order to maintain the Director of Domestic Tranquility's practice of never wearing a sweater or long sleeve anything while inside the house.

We maintained mid to upper 70's all winter this last season. 1/2 bucket when not cold, 1 full bucket when cold, 1 and about a third when it got ridiculous. One bucket of rice coal from Keystone Anthracite ran about 38 pounds.

Exception was when I caught the flu and we had to go back on oil till I got well enough to tend the stove again.

I am looking forward to getting the VC 2310 back together and setting it up. Lite the fire day will be a celebration of going back to a hand fired stove.

My honest to goodness rule of thumb is:

"Whatever it takes to keep Momma happy."

Rev. Larry
New Beginning Church
Ashland Pa.
blrman07
 
Hand Fed Coal Boiler: Bucket a Day
Hand Fed Coal Stove: Vigilant Casting 2310
Coal Size/Type: Pea/Nut/Wood in the VC and anything that will fit in the Bucket a Day. It's not fussy.

Re: Something to ponder for the 'whole house' stoker gang

PostBy: lsayre On: Sat Jul 12, 2014 8:39 am

blrman07 wrote:My honest to goodness rule of thumb is:

"Whatever it takes to keep Momma happy."

Rev. Larry
New Beginning Church
Ashland Pa.


That's a powerful rule of thumb! :clap:
lsayre
 
Stoker Coal Boiler: AHS S130 Coal Gun
Coal Size/Type: Anthracite Pea
Other Heating: Resistance Boiler (if I ever get it fixed)

Re: Something to ponder for the 'whole house' stoker gang

PostBy: SMITTY On: Sat Jul 12, 2014 11:29 am

Math and I don't jive that well. All I know is, right now I'm using roughly 20 lbs. per 24 hour period. In the worst of January, one time I burnt 80 lbs. in the same amount of time.
SMITTY
 
Stoker Coal Boiler: Patriot Coal - custom built by Jim Dorsey
Hand Fed Coal Stove: Harman Mark III (not currently in use)
Coal Size/Type: Rice / Blaschak anthracite
Other Heating: Oil fired Burnham boiler

Re: Something to ponder for the 'whole house' stoker gang

PostBy: coalnewbie On: Sat Jul 12, 2014 1:48 pm

I'm not a numbers guy either but now I think about it the 2.5 rule seems about right. Now all I need is what to do with the information. I know one thing 18 tons from last winter has to be dropped down a lot this winter. If I make 12 tons I will be real pleased. So once I get going past shoulder time this rule will guide me as to whether I stand a dogs chance of making it. good stuff - I think.
coalnewbie
 
Hot Air Coal Stoker Stove: LL AnthraKing 180K, Pocono110K,KStokr 90K, DVC
Hand Fed Coal Stove: Hitzer 50-93,
Baseburners & Antiques: Invader 2 Wings Best, Glenwood #8 + Herald 116x
Coal Size/Type: Rice, Chestnut
Other Heating: Heating Oil CH, Toyotomi OM 22

Re: Something to ponder for the 'whole house' stoker gang

PostBy: Sunny Boy On: Sat Jul 12, 2014 2:53 pm

Don't have a whole house number for coal....yet.

But interestingly enough, that 2.5:1 factor is very close to what my oil burner did when that's all I heated with.

Paul
Sunny Boy
 
Hand Fed Coal Boiler: Anthracite Industrial, domestic hot water heater
Baseburners & Antiques: Glenwood range 208, # 6 base heater, 2 Modern Oak 118.
Coal Size/Type: Nuts !
Other Heating: Oil &electric plenum furnace

Re: Something to ponder for the 'whole house' stoker gang

PostBy: lsayre On: Mon Jul 14, 2014 5:47 pm

Sunny Boy wrote:Don't have a whole house number for coal....yet.

But interestingly enough, that 2.5:1 factor is very close to what my oil burner did when that's all I heated with.

Paul


The count now stands at five who agree with 2.5:1 and one who does not.
lsayre
 
Stoker Coal Boiler: AHS S130 Coal Gun
Coal Size/Type: Anthracite Pea
Other Heating: Resistance Boiler (if I ever get it fixed)

Visit Lehigh Anthracite