# Sizing question (check my calculations)

### Sizing question (check my calculations)

Hi, great forum here!

I am very seriously considering a Harman VFR3000 to replace my oil burner. It feeds cast iron radiators and works well but the time is right to switch.

I use approx. 525 gallons per years. At 142,000 BTU/gallon, that comes up to an annual usage of 74MBTU.

Now, coal is 14,000 BTU/LB, so dividing 74MBTU by 14,000 gives me 5325 lbs, or 2.67 tons.

525 gal X \$3.00 (and who knows what next fall's price will be?) = \$1575

3 tons rice coal in bulk X \$200/ton (?) = \$600

Also, with the hot water coil I'd be saving approx. \$40/month on heating water X 6 months = another \$240 savings

So, bottom line: if I am figuring this right, I'll be saving approx. \$1200 per year.

Am I looking at this right? Certainly makes sense to go ahead with this if my computations are correct.

Priced one yesterday, \$4700 including the hot water coil, delivery, and tax.
nomoreoil

### Re: Sizing question (check my calculations)

Does your 525 gal oil include DHW?

If so (CH+DHW) your annual burn looks pretty good. My calc shows a stoker w/DHW coming in @ 2.8 tons/year on an equivalent to 525 gal oil. Real world, you're probably looking at 3.5 tons.

With your (low) oil price of \$3.00 and \$200/ton coal, you'll save \$1006/year (4.7 year payback on \$4700).

\$3.71 oil (my current), you'd save \$1379/year with a 3.4 year payback.

If your current burn does not include DHW, you're looking at \$1900 savings (w/\$3.71 oil) and 4.5 tons of coal.
Last edited by Charlie Z on Sun Mar 23, 2008 8:36 am, edited 1 time in total.
Charlie Z

Stove/Furnace Make: Coalbrookdale
Stove/Furnace Model: Darby

### Re: Sizing question (check my calculations)

Currently I am using a propane water heater, so yes I will save that when the boiler is running. I do not think I would run the boiler during the warmer 6 months of the year just to make hot water.
nomoreoil

### Re: Sizing question (check my calculations)

I would be a little more conservative in my figures.

I would use about 13,000 btu for my coal and assume less efficiency for the coal boiler compared to the oil fired boiler, especially if the oil boiler is not very old. Remember the coal fire burns all the time, it just gets larger and smaller. I would figure closer to 4 tons annual coal usage. Looking at it that way you are looking at a 5 year return on investment which is not bad considering the boiler will outlast you with proper maintenance.
Other risk factors to consider is the price and supply of coal and oil in the future. No one knows what prices and supplies will be like going forward but it would be safe to assume coal and oil will cost more in the future, how much more, who knows?
gaw

Stoker Coal Boiler: Keystoker KA-6
Coal Size/Type: Rice from Schuylkill County

### Re: Sizing question (check my calculations)

You should find someone that uses a coal fired boiler and go maintain it for a week then multiply that by about 27 and see if your up for the work the 4-6 ash tubs a week gets real old after the first month.
Last edited by Ripple on Sun Mar 23, 2008 8:36 am, edited 1 time in total.
Ripple

### Re: Sizing question (check my calculations)

nomoreoil wrote:Currently I am using a propane water heater, so yes I will save that when the boiler is running. I do not think I would run the boiler during the warmer 6 months of the year just to make hot water.

It would be worth considering. Nothing will prolong the life of a boiler more than keeping it hot forever

You have to see if it can be done for break even, or I would even do it if it cost a little bit more.
gaw

Stoker Coal Boiler: Keystoker KA-6
Coal Size/Type: Rice from Schuylkill County

### Re: Sizing question (check my calculations)

Ripple wrote:You should find someone that uses a coal fired boiler and go maintain it for a week then multiply that by about 27 and see if your up for the work the ash tubs get real old after the first month.

Good point! I am willing to trade a little time and effort for the money saved. I grew up with coal so I knew what I was signing up for when I switched back. Coal heat is not for everyone, consider it carefully.
gaw

Stoker Coal Boiler: Keystoker KA-6
Coal Size/Type: Rice from Schuylkill County

### Re: Sizing question (check my calculations)

You're also using 'gross' m/btu numbers. Everything (except electric) aren't that efficient. Oil boiler and stoker operate at 78% and 72% (conservative) efficiency.

You have net heat needs of 57M/BTU for your central heat requirements (6 mos) and 32 M/BTU for DHW (annually) - 89 M/BTU total, estimated on your oil burn figure

Edit: So, you'd need 2.8 tons for CH (6 mos) and 1.7 tons for DHW (annually) or 4.5 tons.
If you only burn the stoker for 6 mos for both CH and DHW, estimate is 3.7 tons.
Last edited by Charlie Z on Sun Mar 23, 2008 8:57 am, edited 2 times in total.
Charlie Z

Stove/Furnace Make: Coalbrookdale
Stove/Furnace Model: Darby

### Re: Sizing question (check my calculations)

I don't know what boiler Ripple is referring to but I've never had more than two ash tubs per week, even in the coldest of weather. Don't get me wrong, its not "fun" but it is most satisfying to walk past the oil burner and it is silent. I burned 0 gallons of oil this year. For the 2K a year it saves me in oil, I'll carry two ash tubs a week. You don't list your location but the price for the boiler seems alittle high. Where are you?
coalkirk

Stoker Coal Boiler: 1981 EFM DF520
Coal Size/Type: anthracite/rice coal

### Re: Sizing question (check my calculations)

have you considered a keystoker kaa-2 very well built and will last forever. i am heating about the same space as you and i am only burning a bag evey 24 hours. my oil burner only came on once this year and that was for the reason is we were at work and lost power for several hours and the coal went out. you are lookingat huge money savings i plan to break even in 2 years unless oil alls on its face.
1975gt750

Stoker Coal Boiler: keystoker kaa-2
Coal Size/Type: rice coal / blaschak
Other Heating: pensotti oil boiler with riello 40 burner
Stove/Furnace Make: keystoker
Stove/Furnace Model: kaa-2

### I'm in northern Maryland

Very close to the PA line... price is from Finch up in Hanover PA.

What do you guys do to dispose of your ash?
nomoreoil

### Re: Sizing question (check my calculations)

Hi nomoreoil.. check via a search or look in the first forum or the 'best of' forum for threads on ash disposal... there are several long threads on ash disposal..

With your location, choice of boiler, and fuel use, I think you will be very happy burning coal.. Check around for that boiler,, there are several members that bought one from a dealer in NH I think for a very fair price..

Greg L

.
LsFarm

Stoker Coal Boiler: Axeman Anderson 260
Hand Fed Coal Boiler: Self-built 'Big Bertha' SS Boiler
Baseburners & Antiques: Keystone 11, Art Garland

### Re: Sizing question (check my calculations)

I guess the delivery is the difference. That's where I bought mine and my wifes cousin bought his but we both picked ours up. I've got an acre of woods. I use the ash as a paving material for paths through the woods. I'm in Harford County MD and I shopped around. Finch had the best price.
Also, When you say replace your oil burner, are you planning on actually removing it or just not using it?
coalkirk

Stoker Coal Boiler: 1981 EFM DF520
Coal Size/Type: anthracite/rice coal

### I plan to disconnect it

and just mothball it in the basement. That way I'll have it if I ever need to go back to oil.
nomoreoil

### Re: Sizing question (check my calculations)

Ripple wrote:You should find someone that uses a coal fired boiler and go maintain it for a week then multiply that by about 27 and see if your up for the work the 4-6 ash tubs a week gets real old after the first month.

I grew up with coal in an efm conversion stoker which had two conveyors that dumped the ash into buckets. Half the time the buckets were overflowing. After Uncle Sam needed my brother and I, the stoker wasn't far behind in leaving home.

Brought on by the first "energy crisis" in '73/74, we decided to heat with all wood when we built our house in '77 and for the last 31 years I've been adding wood 10 times a day; so there are worse things that can happen than coal ash buckets to empty.

I use the term "worse" loosely. We always enjoyed a warm house and lately, free hot water.
stoker-man

Hand Fed Coal Boiler: 1981 efm wcb-24 in use 365 days a year
Coal Size/Type: Anthracite/Chestnut
Other Heating: Hearthstone wood stove