Written By Heather Hilson.

Posted on September 28th, 2020.

Tagged with Wood Products.

Share it!

Have you ever thought about using an outdoor wood boiler to heat your home? For the past six years, Heather Hilson has used one to keep her house warm during the heating season in Upstate New York. In this week’s blog, Heather shares her experiences with installing, operating, and maintaining an outdoor wood boiler, including installation and operating costs.

In 2004, my husband and I bought a “new” house in Delhi, NY. The house was new to us but it was actually a one-room schoolhouse built in 1860 with an addition added in 1960. Needless to say, the house was in need of some TLC and since 2004 we have been renovating it to the best of our abilities.

The house had baseboard hot water radiators heated by an oil furnace in the basement. The oil furnace also heats the domestic hot water supply. In addition, there was a large woodstove in the basement that vented into the dining room via a floor grate. The system wasn’t very efficient. The wood stove vented into the same chimney as the oil furnace (not safe or up to code). The floor grate only heated the dining room and we used fans positioned around the house to push the warm air to other parts of the house. Plus, the baseboard heaters were ugly (painted several times over), noisy, and furniture could not be pushed up against any wall with a radiator on it - which was most walls. After approximately 10 years living this way with annual fuel costs of $3k-$4k, we decided that an upgrade to the heating system was necessary and we invested in an outdoor wood boiler. The savings in heating costs, positive experiences from friends with outdoor boilers, and improved safety by moving the fire outside the house aided in the decision. Neither of us mind cutting and splitting tree-length logs into firewood and we had been doing so for the woodstove in the basement anyways.

After a little research, we went with a Hawken GX10 outdoor wood boiler that was rated to heat a house of approximately our size (2,000 sqft). I think the equivalent model today is the Greenhawk 10. It’s a gasification model, so it maximizes energy efficiency through a gasification process that the Hawken company calls “Afterburner Technology”. Basically, when operating at full temperature, the only product coming out of the boiler chimney is water vapor. These boilers burn 40% less wood than traditional wood furnaces and the Environmental Protection Agency estimates that emissions are reduced by over 90% compared to traditional furnaces. Amazing right?!

We also decided to upgrade to European-style wall mounted radiators throughout the house, which my husband could install. These are slim heaters that take up very little wall space and can be turned off individually.

image1

Myson radiator – installed.

Luckily, we are somewhat handy and we own a tractor with a backhoe, so we were able to do the site prep by ourselves using plans that were included with the boiler purchase. We also ordered and buried the recommended insulated pipe(s) that circulate the hot water from the furnace into the house, and the electric supply.

image2

The trench for the insulated pipe.

image3

Installing the insulated pipe.

With site prep finished, the wood boiler was delivered and winched onto the prepared pad. Handy we may be, but plumbing in the wood furnace and “piggybacking” it to the oil furnace was well out of our comfort zone. Luckily, we have a friend in the plumbing and heating business who helped us out.

image4

The oil furnace (red in front) and the plumbing for the wood boiler on the wall behind.

image5

The Hawken wood furnace installed with added bluestone slab in front.

In simple terms, here’s how our outdoor wood boiler works:

  • The wood boiler has a firebox for the wood fire.
  • The wood heats the water in a water jacket around the firebox to between 170 and 190 degrees F.
  • The water from the water jacket in the boiler is circulated to a heat exchanger in the basement of the house through 90 ft of buried insulated pipe.
  • The heat exchanger then heats the hot water supplies circulating throughout the radiators, the domestic hot water, and a hot water storage tank in the house.
  •  If the water temperature from the outdoor furnace drops below 170 degrees (for example if the fire goes out) the oil furnace will take over and continue heating the hot water in the house automatically.
  • Two thermostats in the house (upstairs and downstairs zones) regulate the temperature inside the house as they did before.

image6

Log-length wood delivery.

image7

The load of logs ready to be cut, split and stacked for the heating season. 

image8

Here’s where the hard work begins!

Costs (approximately):
Hawken GX10 Wood Boiler: $9,400
Insulated Pipe: $500
Heat Exchanger: $420
Plumbing (labor and supplies): $2000
New Radiators & Fittings (10): $2000
TOTAL: $14,320

Operating Costs:
One tractor-trailer load of log-length firewood every 2 years: $600 - $700
Our time and effort to cut, split and stack the firewood: free

So. Prior to installing the wood boiler we were spending $3k-$4k per year in fuel oil costs. This means that the wood boiler paid for itself in a little less than 4 years and we have saved anywhere between $2.5k-$3.5k per year in fuel costs. During the coldest Upstate NY winters our house is a toasty and constant 70 degrees F.

Other notes of interest:

  • We were required to get a building permit from the town to install the boiler at a cost of $50.
  • The boiler does have to be cleaned once a month during the heating season. This takes around 2 hours and it is dirty work, but it helps the furnace run more efficiently. 
  • When running, the wood boiler has to be filled every 12 hours or so on the coldest days. On warmer days it can be filled every 18-24 hours. 
  • The firewood has to be seasoned for a minimum of 9 months for the boiler to work efficiently (trust me on this!!)
  • There is no loss in water temperature within the 90 ft of insulated pipe that goes from the boiler to the house, even on the coldest of NYS days!
  • The water in the boiler has an additive in it to stop rust forming inside the jacket. We send a water sample in once a year to Hawken for testing to see if more additive is needed. The test is free.
  • We installed a couple of radiators in the basement that were not there before to help keep that space dry and warm. Bonus!
  • Because we only use the wood boiler during the heating season (approximately November through May), we have to utilize the oil furnace during the rest of the year to heat the domestic hot water. This means that our oil bill is close to zero during the heating season and around $300 for the warmer months!

Any questions?
Email me at This email address is being protected from spambots. You need JavaScript enabled to view it.

Helpful links:
Hawken Outdoor Wood Furnaces
Insulated Underground Pipe 
Myson Wall Mounted European-style Radiators


Share it!