Considering the Switch From Oil to Coal

Re: Considering the switch from Oil to Coal

PostBy: LsFarm On: Wed May 28, 2008 10:33 pm

TriciaR wrote:
LsFarm wrote:Hello TriciaR,, Welcome to the forum. I would recommend the following: Keep your existing oil furnace, use it as a backup heater for when you go away for a vacation, or a long weekend. When I say we need to replace the oil furnace it's not just because oil is too expensive, the furnace is corroding and is becoming unsafe - it has an awful lot of aluminum tape on the firebox because of rusting. We were going to replace it with another oil burner but that seems like a real waste of money with the price of oil heading higher all the time. So not sure keeping it in is going to be feasible - will the corrosion stop if we aren't using it? We never leave the house unattended - even when on vacation my dad comes up 2X a day to feed the animals so filling the hopper won't be an issue. I do wonder if having only a coal furnace would affect resale value though?

Install a boiler, use a water to air heat exchanger that installs in the furnaces' ductwork. This transfers the boiler's heat into the ductwork,, this way the house thermostats stil control the heat in the house,, You can stay very simple with the thermostatic controls, or get really 'exotic'.. but you can still control the heat with a thermostat, and use the ductwork to distribute the heat..

Then hook the boiler into you DHW, domestic hot water,, your hot water is roughly 25-30% of your yearly heating bill,, so why not use the virtually free heat from the coal boiler, since it's hot anyway?? Save your electric hot water for the summer. Just curious how much water does a boiler pull from a well? Is it mostly a reservoir and how much water is lost due to evaporation as steam? I have a well that produces approx 2 gallons per minute for about 2 hours before the reservoir is emptied. I try to conserve water and have never pumped the well dry yet but I worry.

Hot air is the poorest conductor of heat,, water is nearly the best.. A boiler will save and store the heat overruns when the thermostat is satisfied, and the ductwork fan shuts off, but the coal fire is still burning strong,, it takes several minutes for the fire to die down,, and this excess heat cannot be stored in forced air furnace.. this is where the boiler is great,, it can store the heat in the water,, letting it get hotter, and then giving the heat off into the house instead of up the chimney between heat demands. Add this feature to the abilty to give virtually free DHW all winter long., and I think that a boiler is the only way to go, even with forced-hot-air ductwork for heat distribution. This type system sounds perfect actually - will have hubby ask about these systems specifically when he goes out looking for info on Saturday (I'm out of town or I'd go with him).

The above system is very common, and works very well, there are quite a few forum members with just such a system.. Hopefully they will show some photos and have a vew comments on their systems.

Greg L.

OK, I didn't understand that the existing oil furnace was corroding away. The corrosion will not stop when the oil burner is no longer used.. But there is no danger of combustion fumes getting in the house through the corroded areas,, the heat exchanger is just circulating hot water..

A boiler does not use any fresh water,, it recirculates the water in the boiler continously,, there is no fresh water added to the system unless there is a leak. it is a sealed system, there is no loss to steam. The systems usually operate at 160-180* well below boiling so there is no steam generated.

The DHW system can be hooked up to heat the electric hot water tank, or most boilers can be equiped with an internal hot water coil for direct heating of domestic hot water.

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

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Re: Considering the switch from Oil to Coal

PostBy: Martin1650 On: Wed Jun 11, 2008 5:28 pm

I have just purcahsed an Alaska Stoker from Tricia's local distrubutor (Berne, NY) after alot of research. Our house is 4200 sq ft and is presently under construction completed this August. I have r-38 in the cellings and r21 in the walls. There is a propane furnance now but with the increase of propane prices we decided to go with the coal stove.
Now for the question, There are three zones in the house, great rm, bedrm area, and upstairs (@1000sq ft), anyone have an idea how much coal I will need to keep the house at 70 degrees? I am thinking about 5 tons!
Thanks for any replys,

Re: Considering the switch from Oil to Coal

PostBy: TriciaR On: Wed Jun 11, 2008 6:53 pm

Actually the closest distributor to me is in Fort Plain. :) I still haven't gone to seem them as Saturday's have all been full and they aren't open on Sunday and not open late enough to go weeknights.

Re: Considering the switch from Oil to Coal

PostBy: rberq On: Wed Jun 11, 2008 8:37 pm

Martin --

5 tons of coal x 25 million BTU per ton x 80 percent efficiency would be 100 MBTU delivered to your house. Can you check with whoever designed the propane system, and find out what they estimated for a season's heat? If they give it to you in gallons you can convert to BTU -- I think the formula is 92,000 BTU per gallon times whatever efficiency a propane furnace provides.

And when you say "propane furnace" do you mean a hot-air FURNACE, or do you really mean a BOILER that feeds hot water baseboards or radiators? Either way you very probably can tie a coal BOILER into the system and keep the propane as backup, since it's there already. Look around on the forum; there are lots of postings about tying two systems together; and about supplying your domestic hot water from the coal boiler as well.

You say you've done a lot of research, so I'm assuming you have sized the coal system to provide enough BTU per hour to meet peak needs. Again a cross-check against the propane design should give a reality check, though in my (limited) experience installers tend to oversize oil and propane systems.
Hand Fed Coal Stove: DS Machine 1300 with hopper
Coal Size/Type: Blaschak Anthracite Nut
Other Heating: Oil hot water radiators, propane

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