Things to Consider When Buying an Outdoor Wood Boiler

Factory warranty, wood furnace design and quality of materials should be on the top of your list when choosing your outdoor wood furnace or indoor wood furnace. There are many options out there so be please be careful when making your chose. Question your dealer to make sure that he or she gives you accurate answers to your questions.  Royall™ dealers are very good at what they do and will tell you if Royall™ brand products are a good fit for your application needs. 

Please check the following when considering outdoor wood furnaces for your home.  Remember that this is the opinion of Royall™ and you have the right to disagree.

Furnace door

The fuel door can be a large safety factor.  Having an access door that you must open before reaching the fuel door is a huge safety benefit.  If you have any children that would play around the outdoor wood boiler, this benefit would put your mind at ease. 

Fuel door gaskets

The best doors for your wood furnace (in Royall™ opinion) are made of cast iron and have a recess in the door gasket for a firm fit to your door jam. This is recess in the casting is covered by a fireproof rope gasket that makes an air tight seal. Silicone or rubber gaskets will melt or become deformed due to the heat and eventually break down. An air leak in your door can cause run-away fires.

 Fuel door construction

Fuel doors need to be adjustable in all directions; however, if you don't have a gasket rope seal in the door itself, the adjustment of the door will not make a difference.  From Royall™ experience, water jacketed doors are more prone to corrosion and also have hoses that can leak. Doors that are close to the ground make the stove hard to open and hard to load wood in the winter. This type of door requires constant removal of debris. 

Legs vs. skirting

A greater chance of heat loss is eminent with a boiler that sits on the ground or is sand filled.

Rust control

This needs to be addressed with all outdoor wood boiler manufactures.  Many if not all outdoor wood furnace manufactures have a rust factor spelled out in there warranties.  You must read the warranty to understand this issue to find if you are covered should anything unforeseen happen to your outdoor wood boiler.

What kind of steel is appropriate?

Remember that this is Royall™ opinion.  Stainless steel is truly meant to hold water, dairy products and fuels; not hold water while burning acidic wood and boiling out the water that is keeping the steel cool.  Stainless will fatigue and breakdown should this happen.

409 stainless is not the answer either. 

Mild steel has the ability to be welded should there be a breakdown in the outdoor wood boiler.  Mild steel will rust out over time if you have an outdoor wood boiler that is non-pressurized.       

What is the deal with antifreeze?

Antifreeze is used in case of a power outage for freeze protection.  Antifreeze also enhances the thermal conductivity of the water during the heat transfer process.  Antifreeze when used in outdoor non-pressurized wood boilers will boil out over a short time frame.  In all sincerity, antifreeze is a debated argument amongst heating contractors.  A simple answer to this issue is very simple – keep your circulation pump that transfers the hot water back to your home circulating at all times.

What are the differences in insulation?

There are three types of insulation: glass, spray foam and bubble wrap. Supposedly, spray foam has a better R value per inch than any of the other types of insulation; however, when exposed to the continuous amount of heat from your outdoor wood furnace, it tends to crystallize and break down. Outdoor wood furnaces will condensate, but foam insulation does not allow it to breathe causing corrosion or the rust factor that was talked about above. The use of bubble wrap only works if used on top of another type of breathable insulation.  Make sure the insulation you have can breathe.

Water jackets

Over the years, this has been a debate whether to have a water jacket extend underneath the actual flame or keep the water jacket at the same level where the wood sits during combustion.  Royall™ products are a horseshoe style water jacket and sit at the level of the fire wood.  We can prove that this design works with over forty years of manufacturing our pressurized outdoor wood boiler.

Water storage

People have the tendency to think that more water is better.  This is not an accurate statement.  Outdoor non-pressurized wood boilers do need to have an abundance of water to maintain water levels.  Royall™ brand pressurized wood boilers are a true boiler that works like a Rinai water heater by giving you heat on demand.  Less water do not mean more wood or shorter burn times, it is actually the opposite of that.  Royall™ does urge and strongly promotes using water storage tanks specifically for our gasification line of wood boilers.  Contact your local dealer for further information.

Natural drafting vs. forced draft combustion

Natural drafting outdoor wood furnaces tend to smoke more than forced draft.  When considering outdoor wood boilers, look for placement of the draft fan.  Does the fan blow right into the firebox, or does it blow under the grate system that the manufacturer has designed.  Technically, you can shut down an outdoor wood boiler when loading the boiler with wood when you have a draft fan than one that drafts naturally.  Safety is important. 

Pressurized vs. non-pressurized wood boilers

When considering an outdoor wood boiler, consider a pressurized boiler.  Pressurized boilers that are built to the American Society of Mechanical Engineers standards are very good boilers.  These wood boilers will last the test of time.  Royall™ brand boilers have over forty years of empirical data to back this statement.  Royall™ pressurized wood boilers virtually do not have any warranties to speak of.  True heating contractors will tell you that a pressurized boiler with that kind of certification is rare and would rather install them versus the other type of outdoor wood boiler that this more prone to warranties.

Ash removal

Look at the outdoor wood boiler that you are considering purchasing and imagine how you are going to safely remove the ashes from the wood boiler.  Outdoor wood boilers and indoor wood boilers that have actual ash doors will be safer and much easier to clean out.  Wood boilers that have the ash system that requires a shovel to remove the ash from the fuel door are harder to work with.  In addition, you will have to build a new fire every time you clean your ashes out.

Warranty

Look really hard at the warranty.  The number one thing is the overall years of full coverage.  If a company is offering a twenty year warranty and they have not been in business for that amount of time could raise a red flag.  Companies often (including Royall™) have a prorated warranty.  Royall™ wood furnaces start prorating after the fifth year of use.  Always make sure the warranty spells out the manufacturers rust factor.  You have made an investment for the future not replacing your investment in five to seven years.  For the record, you do not have warranties with a pressurized outdoor wood boiler.