W.E.Reynolds,L.L.C. Heating Contractor |
| Wood Boilers and Furnaces |
Providing heat through a central heating system, using motorized or thermostatically operated dampers allow wood boilers
and furnaces to have a controlled burning rate based on demand. However, just like a wood parlor stove or fireplace, you
have to put the wood in the firebox two or more times a day. Without a form of automatic back-up heating, you can not
leave for more than half a day.
Today's Wood Boilers and Furnaces are available in several basic designs;
Before Installing a Wood Boiler or Furnace;
Wood systems will heat your home..........But it involves work.
and furnaces to have a controlled burning rate based on demand. However, just like a wood parlor stove or fireplace, you
have to put the wood in the firebox two or more times a day. Without a form of automatic back-up heating, you can not
leave for more than half a day.
Today's Wood Boilers and Furnaces are available in several basic designs;
- Natural Draft or
- Forced Draft / Gasification
- Stand-alone wood or
- Combination wood & oil / gas
Before Installing a Wood Boiler or Furnace;
- Check with your insurance company,
- Determine if the addition of a wood burning unit will affect your premium,
- If additional coverage is needed, or
- If coverage would be excluded.
- How many flues are there?
- Generally a Stand-alone wood unit can not be installed in the same flue with another appliance.
- Check that the flue is in very good condition, has an interior size equal to or greater than the cross sectional area of
the flue connection on the furnace or boiler........ and it must be lined! - Think about living with wood,
- Do you have wood to cut, and if so how much time will that involve?
- Will you have to buy wood and how much will it cost?
- Remember there will alway be some mess around the wood unit.
- If wood is stored in the house be aware of termites.
- Wood contains moisture, moisture can be released into the house.
- Even with the wood unit in the basement there will likely be smoke or at least the smell of smoke in the house.
- Ask a Realtor how it will affect the value of house,
- Combination units are still primarily wood units and usually burn wood very well, but lose efficiency when run in
the oil mode. - Even with automatic controls, wood fires do not stop and start like oil or gas. In the spring and fall the unit may
over heat the house and room temperature may make wider temperature swings than conventional systems.
Wood systems will heat your home..........But it involves work.
The choice between a combination wood & oil / gas and a straight wood unit is more a matter of the manufacturer's design
requirements and how those requirements match with your site.
The choice between a natural draft and a gasification wood boiler has more to do with efficiency.
A typical natural draft unit will operate much like a wood stove. There will be a damper, operated by a thermal control. When
there is a call for heat the damper is opened. Air movement through the firebox increases, the fire burns hotter. When the call
for heat ends, the damper closes down, but continues to burn.
In a gasification wood boiler, the operation is more like an oil or gas boiler operation. On a call for heat a blower starts. As the
fire burns, combustion gases are forced through a high temperature ceramic combustion chamber. Secondary air is mixed
with the combustion gases and a temperature of 1800 degrees is produced. This type of combustion is much more complete
then a natural draft type unit's combustion. These units should produce little to no tars or creosote, with an efficiency of 80%.
Between heat calls, once a fire is established, the heat retained in the ceramic is high enough to maintain and restart the
combustion process when the next call for heat occurs.
There is also a substantial price difference these two types of units. (See the "LINKS" section for links to manufacturers)
requirements and how those requirements match with your site.
The choice between a natural draft and a gasification wood boiler has more to do with efficiency.
A typical natural draft unit will operate much like a wood stove. There will be a damper, operated by a thermal control. When
there is a call for heat the damper is opened. Air movement through the firebox increases, the fire burns hotter. When the call
for heat ends, the damper closes down, but continues to burn.
In a gasification wood boiler, the operation is more like an oil or gas boiler operation. On a call for heat a blower starts. As the
fire burns, combustion gases are forced through a high temperature ceramic combustion chamber. Secondary air is mixed
with the combustion gases and a temperature of 1800 degrees is produced. This type of combustion is much more complete
then a natural draft type unit's combustion. These units should produce little to no tars or creosote, with an efficiency of 80%.
Between heat calls, once a fire is established, the heat retained in the ceramic is high enough to maintain and restart the
combustion process when the next call for heat occurs.
There is also a substantial price difference these two types of units. (See the "LINKS" section for links to manufacturers)
PERSONAL OPINION:
My preferred installation; is a split system / stand-alone units, that is, one in which the wood is a separate unit from the
back-up oil or gas unit.
Reason 1: Wood units are designed to burn wood.
A wood boiler should have a large water volume. Why? Volume is needed to store heat so that when the thermostat calls,
there is a large mass of hot water to prevent thermal shock to the boiler and allow time for the damper to open and the fire to
build. Oil and gas boilers require much less water volume because they are able to come up to operating temperature faster.
In fact while a wood boiler may hold 30 or more gallons of water, high efficiency gas boiler of equal or greater BTU output may
contain less then one gallon of water. Efficiency involves not only how well the fuel is burned, but how much fuel you have to
burn, to get heat into the living area. Burn wood in wood units, burn oil or gas in heaters designed for oil or gas.
Reason 2: Wood units are often going into existing houses where there is only one chimney flue. Unless the two units are
single flue listed (approved for combined use in a single flue) two flues are required. To eliminate having to build a second
chimney, install a direct vent oil or gas heater tied into the central heating system, along with the wood unit. Direct vent means
that the unit can be vented out the side of the building without connecting to a chimney. In fact many high efficiency gas units
vent to the outside with standard schedule 40 PVC pipe, the same type used in the plumbing piping. Having separate units
also means that if the house is sold, and the new owner does not wish to burn wood, the wood boiler may simply be shut off.
The system can then be operated with the oil / gas unit achieving a better operating efficiency than would be achieved with a
combination unit used solely in the oil or gas mode.
My preferred installation; is a split system / stand-alone units, that is, one in which the wood is a separate unit from the
back-up oil or gas unit.
Reason 1: Wood units are designed to burn wood.
A wood boiler should have a large water volume. Why? Volume is needed to store heat so that when the thermostat calls,
there is a large mass of hot water to prevent thermal shock to the boiler and allow time for the damper to open and the fire to
build. Oil and gas boilers require much less water volume because they are able to come up to operating temperature faster.
In fact while a wood boiler may hold 30 or more gallons of water, high efficiency gas boiler of equal or greater BTU output may
contain less then one gallon of water. Efficiency involves not only how well the fuel is burned, but how much fuel you have to
burn, to get heat into the living area. Burn wood in wood units, burn oil or gas in heaters designed for oil or gas.
Reason 2: Wood units are often going into existing houses where there is only one chimney flue. Unless the two units are
single flue listed (approved for combined use in a single flue) two flues are required. To eliminate having to build a second
chimney, install a direct vent oil or gas heater tied into the central heating system, along with the wood unit. Direct vent means
that the unit can be vented out the side of the building without connecting to a chimney. In fact many high efficiency gas units
vent to the outside with standard schedule 40 PVC pipe, the same type used in the plumbing piping. Having separate units
also means that if the house is sold, and the new owner does not wish to burn wood, the wood boiler may simply be shut off.
The system can then be operated with the oil / gas unit achieving a better operating efficiency than would be achieved with a
combination unit used solely in the oil or gas mode.
 |
| |
 |
| |
 |
| |
 |
| |
 |
| |
 |
| |
 |
| |
 |
| P.O.Box 494, Turner, Maine 207-225-2126 (office & fax) 207-240-1407 (cell) |