Frequently Asked Questions

For Customers

The Greenwood Frontier Series is designed to be installed so that it is sheltered from the weather in your basement, garage, shed or other protected location. It meet strict ETL and CSA standards for indoor heating appliances, so it is safe to install in a building.

Important Note: Installation must comply with local building codes and state/local regulations. Residents of the State of Vermont should insure compliance with state regulations referenced here.

The Greenwood wood furnace do one thing extremely well — it produces  hot water. You can use that hot water in almost any way you and your heating contractor can imagine:

– hydronic radiant heating (in-floor, radiators or baseboards) for your home, garage and outbuildings

– forced air heating (using a water-to-air heat exchanger that fits into existing ductwork)

– domestic hot water (in conjunction with your existing water heater)

– heating a hot tub, swimming pool or greenhouse

– melting the snow on your walk and driveways

While a perfect 100% combustion efficiency is not possible to achieve, Greenwood Frontier CX come close to it. Temperatures in the firebox approach 2000º F, assuring maximum gasification of the wood fuel. Little particulate matter remains to create smoke, creosote or ash.

Greenwood systems are some of the most energy-efficient hydronic wood furnaces on the market. It achieves up to 85% thermal efficiency depending on the stage of the burning cycle. 


Greenwood appliances have been designed and tested to ETL-391 (U.S.) standards for solid-fuel and combination-fuel central and supplementary furnaces and CSA B366.1-M91 (Canada) standards for solid fuel-fired central heating appliances.

In February 2007, the U.S. Environmental Protection Agency announced the voluntary EPA Outdoor Wood-fired Hydronic Heaters Program. The HH program encourages wood boiler manufacturers to improve air quality through developing and distributing cleaner, more efficient outdoor wood-fired hydronic heaters, like the Greenwood Frontier Series wood boiler and Greenwood Denali Series pellet boilers. This program is a recommendation by the EPA and each State will evaluate if and how it will apply it. We are in complete support of tighter air quality standards and the programs that lead to them. Program qualified units are easily identified by an White Tag.


A single hydronic wood furnace can provide heat and hot water for your home, as well as your garage, greenhouse, barn or other outbuildings. It can also heat your swimming pool and even provide snow-melt for your walks and driveway. A simple network of insulated pipes or PEX tubing can connect the wood boiler to each location. Keep in mind that each application adds to the demand on the furnace, so it is important to plan ahead and install a unit with sufficient capacity to handle the full load.

Correct sizing of the hydronic furnace is very important for safe and efficient operation. The installation contractor will perform a heat load analyses of your home to determine the wood furnace output required and assess your desired operating behaviors to determine which unit is appropriate for your situation. Many factors must be considered in determining the size of the wood furnace you need, including local winter temperatures, size and insulation rating of your home, additional applications or requirements for heat, and so on.


We are not able to help individual consumers but rather refer this work to a local resource — the Authorized Greenwood dealer, architect, or HVAC contractor, in your area. Local building codes and regulations vary from location to location. An on-site visit will determine the proper location and installation details.

The Greenwood Frontier Series work best when burning seasoned cord wood. Burning wet or unseasoned log wood will lower the efficiency of the system and potentially create smoke and other byproducts that will degrade the long-term performance of your unit. As far as the type of wood to use as fuel, some species produce more heat than others, however we recommend burning whatever wood species is most readily and economically available in your area.


The Greenwood Frontier wood furnace is designed, built and certified to burn solid wood fuel only. Other fuels such as dimension lumber, pellets, corn, oil, railroad ties, trash, etc., are likely to cause over-firing of the furnace or other unsafe conditions. Use of any fuel other than solid wood will void the furnace warranty.

The burn duration of each wood load depends on the amount of wood loaded and the demand for heat. You should tailor the amount of wood placed in the firebox to the current weather conditions. If the weather is severe and there is high demand for heat, the firebox should be fully loaded and refilled every 8-12 hours, and sometimes more often. If conditions are milder, less wood is required and the firebox should be checked every 12 hours. Please see the load – output chart to better understand your reload frequency.

The Greenwood Frontier firebox is made of refractory ceramics which is specially formulated to withstand high temperatures and act as a storage reservoir for heat. The firebox is made of super-duty, cast ceramic refractory. The firebox walls are 2 to 4 inches thick and will withstand years of use. 


There are several answers to this question. Inside the firebox the temperature reaches 2000º F, but thanks to our unique design, the outside surface is only warm to the touch. The temperature of the heat transfer solution reaches 180º F as it flows out of the wood boiler. The temperature of exhaust gases range from 250 – 450º F depending on firing rate.


We recommend a vertical flue that is at least 12 feet tall. Proper chimney sizing and venting are extremely important to the efficient and safe operation of the furnace. Your installation contractor should check for local code requirements and carefully follow the instructions in the Greenwood Owner’s Manual.

The size of the flue pipe varies with the size of the furnace. The Model CX requires a 6 inch flue.

Greenwood’s wood boiler provides heat-on-demand and does not require a large hot water storage tank.

We recommend keeping the existing heating source (e.g. furnace, boiler, etc.) as your backup. Greenwood systems are the most efficient way to heat your home during the heating season. But at other times of the year, when heating demands are drastically less, there are more economical ways to heat your home. If this is a new construction, we recommend installing a high efficiency gas or oil water heater (Bock or Polaris are excellent choices) in parallel with your Greenwood wood boiler. The water heater serves as the back-up heat source in winter and the primary in summer.

Your first point of contact for support your dealer or contractor. In most situations, Greenwood will refer you to your local dealer, but if necessary you may also contact Greenwood at Our dealer support team will reply as soon as possible.

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