What You Need to Know About Gasifying Pellet Boilers
Mainers are looking for home heating alternatives that are cheaper and more environmentally friendly than burning fossil fuels. The good news is that today's high-efficiency gasifying boiler technology gives us the option to heat with locally produced and sustainable wood pellets. ReVision Energy has installed many pellet boilers and our goal is share our wisdom and experience such that you can make an informed decision about whether a pellet boiler is right for you.
Environmental Impact
Gasifying wood and pellet boilers are 'carbon neutral' if the fuel supply is sustainably harvested from Maine woodlots. Carbon neutral means that the small amount of CO2 emitted by the boiler is actually 'digested' by the remaining live trees on the woodlot, resulting in net zero atmospheric emissions. Studies have shown that Tarm gasifying boilers emit less than 1 gram of smoke per hour-equivalent to the amount of smoke produced by one cigarette. The laws of Physics dictate that fossil fuels can never be sustainably harvested, nor combusted with net zero emissions. In Maine, the sustainable harvesting rule of thumb is that an acre of land can produce between one-half cord to one full cord of firewood per year. As long as the wood or pellet fuel is burned in a high efficiency gasifying boiler, the net emission effect is zero.
Pellet Logistics & Volume
Pellets can be bought from your local hardware store in 40 lb. bags, but most people with a pellet boiler have pellets delivered to their driveway by the ton. Delivered pellets come on a pallet that holds 50 bags (each bag weighing 40 pounds). The homeowner is then responsible for getting each 40 lb. bag of pellets into the basement. It takes about an hour for one able-bodied person to carry a ton of pellets down a flight of stairs by hand. Although automatic fuel supply technology exists for pellet boilers today, we are still waiting for the infrastructure to deliver pellets in bulk to the basement. Europeans commonly have wood pellets delivered directly into their basement storage by a delivery truck and we anticipate this luxury becoming available to Mainers with the next year or two.
To get an idea of your pellet fuel requirements, it's good to know that a ton of pellets burned in a Tarm pellet boiler will offset roughly 130 gallons of oil (this ratio fluctuates based on how high you set your thermostat and how well your home is insulated). If you're burning 900 gallons of oil in a heating season, you'll need roughly 7 tons of pellets. ReVision Energy can give a more accurate estimate of total pellets needed through a site evaluation.
Saving Money
Many people see a pellet boiler as a great way to save money on heating costs. How much will you save if you burn pellets in a high-efficiency gasifying pellet boiler? If each ton of pellets has the same amount of fuel as 130 gallons of heating oil, and pellets cost is $285 a ton, then each ton of pellets you burn will save you $235 compared to the equivalent amount of oil at $4 a gallon. Obviously, the price of pellets and oil will change over time, and that will affect savings. In general, most people believe that the days of cheap oil are over and wood pellet fuel-well, it grows on trees.
Elbow Grease
Pellet boilers need tending on a regular basis. Tarm pellet boilers have large storage hoppers affixed to the boiler and they burn fuel very efficiently; as a result, they only require trips to the basement every 2 to 3 days during the coldest winter months, and less during the other seasons. Pellet boilers should have the ash pan cleaned every week or so during the coldest months, and less often as the season warms.
Shoulder Seasons and Summer Domestic Hot Water
Pellet boilers don't want to run for long periods without a demand for heat. On warm days in the spring and the fall, the boiler should be either be shut off, then lit again at night, or shut off altogether to allow the backup boiler to take over.
The future of Wood Pellets
For a great white paper on the future of wood pellets, go to the Maine Pellet Fuel Association at www.mepfa.org/White_paper_section_description.htm. This paper lays out the price structure of pellets, and the long term future of the resource.
Does this sound like a lot of work? If it does, pellet boilers might not be for you, or, you may have to wait for the next generation of pellet boilers that has automatic feed capability built in, and bulk delivery. Then pellet boilers will be a lot more like oil boilers, and a lot more expensive.
Still Serious About a Pellet Boiler?
Then read on!
The Flue
Your pellet boiler needs a flue. The flue for the boiler needs to be dedicated (no other appliances on the flue). This may change over the next year or so, but, as of today, you need a spare flue with nothing else occupying it. There are many issues related to proper flues. This is not meant to be a definitive design guide, but a preliminary list to qualify a chimney's suitability for a solid fuel boiler and to give some indication of where the boiler should be installed.
Masonry Chimneys
If there is a masonry chimney, that chimney needs to be lined with a ceramic liner at a minimum; a stainless steel insulated liner is best. If the masonry chimney is on the exterior of the residence, or if there are places where wood is within 2" of the chimney, the masonry chimney needs to be lined with a "supa flue" product, which is a stainless steel, insulated and lined chimney: (http://www.supaflu.com/products.htm). It is never wrong to line a chimney with insulated pipe, as this keeps the flue gasses warm and keeps creosote from condensing.
Metal Chimney
If you have an easy venting situation, such as a one story house, or a boiler in the garage or a shed, installing a metal chimney can be a good solution. Check out http://www.selkirkcorp.com/Selkirk/Product.aspx?id=208. Metal chimneys are easy to install, and are usually installed by carpenters. Chimneys need to terminate 2 feet higher than any roof 10 feet away. All of the Tarm Pellet Boilers are designed for 6" masonry chimneys.
Pellet Boiler Backup System
Your pellet boiler needs backup for a number of reasons-to keep the insurance company happy, to keep your house from freezing if you're not around, and, if you don't have thermal storage, to provide domestic hot water in the non-heating season. If you do not have a spare flue, here are your options:
- Power-vent the oil boiler
- Install a direct vent gas boiler or an electric backup boiler.
- Install a new Insulated metal type HT flue
Power Vent the Oil Boiler
If you want to keep your existing Oil boiler, but only have one flue for the wood boiler, one option is to power vent the oil boiler. Power vents can be installed on most modern oil boilers. Termination requires 4' from windows and doors. Power venting typically adds roughly $1000 to $1500 to the cost of the installation.
Gas Boiler Backup
If the oil boiler is on its way out, or you want to switch from oil to propane or natural gas, consider switching to a gas-fired low mass boiler. Oil makes a poor back up fuel, due to the fact that oil boilers are high mass and, as such, they run very inefficiently in periods of low demand. Oil boilers maintain efficiencies of roughly 20% of the their rated efficiency during the non-heating months (when used for domestic hot water only).
The Prestige gas boiler is a beautiful boiler that we've installed with lots of success. It's a simple boiler, easy to install, and maintains very high efficiency, even during periods of low demand. (http://www.triangletube.com/CondensingBoilers/PrestigeOverview.htm) For Projects where up-front costs are a factor, and where gas usage is expected to be minimal, we recommend the Biasi Riva. This is a non-condensing boiler, but is well-built by a respected European manufacturer, and is the one of the best values for wall hung boilers.
Schematic Diagram of Tarm pellet boiler with gas boiler backup:
Electric Backup
It sounds crazy, but electric back up makes more sense every day. When you heat primarily with wood pellets, a back up system is just that. It provides domestic hot water during the non-heating season and heats the house while you're away. Ideally, a back up system is inexpensive to install, reliable, and burns fuel efficiently during low demand. Electric back up boilers do all that. At current prices, look at how various fuel options pan out in terms of $ per Million BTU's.
For current fuel prices see http://tonto.eia.doe.gov/dnav/pet/pet_pri_wfr_dcus_sme_w.htm.
- Wood @$200 per cord…………$10 per M BTU
- Pellets@$280 per ton…………$17 per M BTU
- Oil @ $5 per gallon…………$36 per M BTU
- Propane @$3 per gallon…………$32 per M BTU
- Electricity @ $.15 per KWHR…………$44 per M BTU
These numbers represent raw energy, so they don't take efficiency into account. Electricity at 100% efficiency costs less than oil at 40% efficiency, which is what you'll see most oil boilers perform at in a backup capacity. We use the thermolec electric boiler (www.thermolec.com).
Schematic Diagram of Tarm pellet boiler with electric boiler backup:
Boiler Location Options
The Basement
There are several issues that need to be addressed when figuring out the best place to install your pellet boiler, including flue availability, access for wood storage and delivery and arrangement of heat distribution. If you have good access to the basement, either through a walk out basement or a nice bilco door, and you have a spare flue, then the basement is a no-brainer. If you don't have a spare flue, and power venting or adding new boilers is not attractive, or you don't have good access for bringing pellets into a basement, then you might consider the garage or a shed.
The Garage
Maine law makes garage installations tough. You can not open a door from the room that stores the wood boiler directly into a room that can store a car. You can build a hallway, make a room that you can only access from the outside of the garage, or you can wall off one half of a two bay garage and make it so a car can't park in the half with the wood boiler. The state is concerned that if an automobile gas tank develops a leak, the flame in the wood boiler could ignite the gas. The garage is a great site because it can make pellet loading easy, and venting is also straightforward, but you have to be prepared to lose the ability to park a car. Also, you'll have to consider make up air AND freeze protection if it's in the garage.
Build a Shed
A shed is a great place for a pellet boiler, either attached to the house or free standing. Of course, a boiler in a remote shed will require painstaking measures to insulate the boiler piping between the shed and the house. Boilers installed in sheds are easy to vent, and easy to bring pellets to. The nice thing about building a shed for the pellet boiler is that the same shed can store the pellet fuel.
The Boilers
Currently, the Tarm Multi Heat is the only pellet boiler that we offer. We like the fact that it is the most efficient pellet boiler on the market today. It is a horizontal tube boiler, which means that it does a better job of pulling heat out of the flue gases. It has a modulating fan, which means that it runs longer at lower rates, compared to a binary fan. It has a fantastic warranty, and it is a time-tested European boiler built by a company with 70 years of experience. The Multi Heat can be adapted for automatic fuel feed, but it was primarily designed as a hopper fed boiler; it has a very large hopper. The boiler comes in three sizes: 50,000 BTUs (MH 1.5), 85,000 (MH 2.5) and 135,000 (MH 4.0). For most houses, currently using up to about 1200 gallons per year, the MH 1.5 is more than adequate. We prefer to undersize our boilers, to the extent that on the very coldest nights, the backup boiler may need to fire. Undersized boilers burn more efficiently the rest of the year. The Tarm MH does not have automatic ignition, but rather features a pilot mode, which slows the pellet feed to a trickle just sufficient to maintain a small flame until there is a new heating demand.
Rough Prices
How much is all of this going to cost? The short answer is that you need to think of this as a long term investment that will pay for itself over time. More important than saving a few thousand dollars on such a large, long term investment is setting yourself up for something that you can live with for a long time. It needs to suit your needs and your life. It needs to be the right boiler for the job, and system needs to be properly designed and installed.
It is very difficult to put down installed costs on paper because every house is different and therefore every installation is different. Distance from our shops is a factor for us when we price installed systems. The prices below are simply ballpark rough estimates. Once you have a clear idea of what system seems right for you, we're happy to schedule a site visit to determine actual costs for your location, and to thoroughly assess feasibility (please read about scheduling a site visit below).
If there is an existing flue, and relatively easy access to the basement, and not a lot of surprises in the installation, the full service, installed price of a pellet boiler is in the neighborhood of $20,000 for a Tarm Multi Heat 1.5 and upwards of $23,000 for a MH 4.0.
In general, installation costs about $7,500-this is the fee that you add to our "built boilers" pricing. Built boilers include pumps, controls, and safety equipment, already built in our shop and ready to go. Please refer to our "Boiler Pricing Options" sheet for built boiler prices of various boilers. Difficult delivery, additional overheat protection, piping modifications, or the need for installing additional controls will all push the installation costs higher.
If a spare flue is not available, keep in mind that the installation of a power vent for an existing oil boiler usually adds between $1000 and $1500. Installation of a Gas Direct Vent back up boiler adds between $5,000 and $9,000. Installation of an Electric Back up boiler adds roughly $4,000 and requires a 200 amp electrical service.
Who Should Install your Wood Boiler?
ReVision Energy can provide you with any level of service; from full installation to A La Carte Pricing for the services you receive. Our technicians are fully licensed and insured. If you are interested in dealing only with ReVision Energy, and you are willing to pay for our premium service, we are happy to be your full service installer. If you have a fixed budget in mind, and you want to get the lowest-priced installation, then working with our A La Carte Menu and finding an installer local to you may be more attractive.
With our A La Carte Menu, you purchase only the level of services that you need to get the job done right. We can sell you a "naked" boiler in our shop, and avail ourselves to you or your installer for stock drawings for piping and wiring, and we can answer any questions over the phone. We can also offer custom design services, delivery, and boiler firing or troubleshooting as needed.
Want to Learn More?
Contact ReVision Heat for a free pellet heating consultation!
Or call us, (207) 989-8500.
