Navigating Boiler Choices

Wood boilers are a great heating choice for families and businesses seeking sustainable and cost effective heating solutions especially in rural and off grid locations. There are, however, many misconceptions and misleading information about these heating systems. One fundamental issue stands out: are pressurized or non-pressurized boilers the superior choice?

This guide attempts to outline the differences between these two boiler types and address some common misconceptions about pressurized boilers that are prevalent in the industry. We will discuss the pros and cons of each system, what circumstances make sense for each type of system, and how to mitigate common issues and concerns with each type of boiler.

Pressurized Boilers: Efficiency Champions

Pressurized boilers, also known as closed-system boilers, operate under low levels of pressure (typically under 30 PSI) to produce hot water for heating. These boilers offer numerous advantages:

1. Enhanced Efficiency: The pressurized environment within these boilers boosts heat transfer efficiency, resulting in more effective heating with reduced energy consumption. This increased efficiency translates to lower utility bills and reduced environmental impact. In side-by-side tests, we have regularly seen our pressurized boilers provide as much or even more heat than their non-pressurized counterparts while using up to 50% less wood over the course of a heating season. That can mean reducing your wood use from 20+ full cords in a season down to 10 cords or less depending on the quality of the wood you burn and your specific heating needs.

2. Consistent Performance: Pressurized boilers maintain a steady pressure level, ensuring consistent heat delivery throughout the system. This ability to maintain consistent temperatures throughout the entire system reduces wear and tear over time due to drastic heat fluctuations which can crack, twist, and compromise the integrity of the boiler. Consistent temperatures also allows wood to burn steadily for optimal fuel utilization and provides occupants with stable heat.

3. No Need For Water Treatments or Lab Results: Most unpressurized boiler manufacturers require that you use their proprietary water treatment formula and, in some cases, distilled water in their boiler. They also require that you collect and send test samples to them every single year to verify you are using the correct water to retain your warranty. This is a frequently overlooked detail in the fine print that regularly causes boiler owners to inadvertently void their warranty. Pressurized boilers, however, do not need to be filled with treated water. The pressurization drastically reduces the amount of corrosive oxygen in the system so the boiler can last significantly longer than even the most meticulously maintained unpressurized systems with no tests, treatments, and no lost warranty.

4. Space-Saving Design: With compact and streamlined designs, pressurized boilers require minimal space, making them suitable for indoor installations in tight quarters such as utility closets or boiler rooms. Indoor boilers also keep you out of the elements when it’s time to add more fuel.

5. Compatibility with Modern Systems: In most cases, pressurized boilers seamlessly integrate with modern radiant heating and under floor heating systems, offering versatile solutions for diverse heating needs.

6. Never Need to be Refilled: Pressurized boilers are outfitted with an auto-fill valve as part of a standard installation. This means that they always stay filled to the optimal level without you needing to raise a finger! This is a major benefit over unpressurized boilers as you typically need to add water to an unpressurized system every 3-7 days depending on your circumstances. Neglecting to maintain the proper water levels in a boiler can lead to catastrophic warping, cracking, and leakage. It is important to note that damage due to neglect and under filling is not typically covered by warranty which may leave the homeowner liable for thousands of dollars worth of repairs or in need of a new boiler altogether.

Despite their many benefits, pressurized boilers have some drawbacks:

• Higher Initial Cost: The upfront cost of installing a pressurized boiler may be higher than non-pressurized alternatives. However, the long-term savings from improved energy efficiency often offset this initial investment.

• Complex Installation: Professional expertise is recommended for the installation of pressurized boilers due to the complexities associated with pressurized systems. Homeowners may incur additional expenses for professional installation services.

• Fear of Being “Pressurized:” One of the most common hesitations we see with pressurized boilers is the fact that they are pressurized. This word seems to create mental images of pressure cookers full of mashed potatoes exploding all over the kitchen ceiling. A pressurized boiler, however, is nothing to be afraid of. Most systems are pressurized at or below 30 PSI and include multiple pressure relief safety features. For some context, your water heater is somewhere around 100 PSI and the plumbing inside your home is typically around 60 PSI. 30 PSI is equivalent to a garden hose or most faucets in your home and poses no threat of exploding. In fact, the pressure serves many important purposes including preventing the water inside the system from freezing and damaging your boiler or plumbing.

Non-Pressurized Boilers: Traditional Reliability with Risks

Non-pressurized boilers, also known as open-system boilers, operate at atmospheric pressure. While they offer simplicity and reliability, they come with their own set of risks:

1. Simplicity of Design: Non-pressurized boilers feature straightforward designs, making them easy to install and maintain. Homeowners with basic DIY skills may find these boilers more accessible.

2. Lower Initial Cost: Non-pressurized boilers typically come with lower upfront costs compared to pressurized counterparts, making them attractive for budget-conscious consumers.

3. Essential Equipment Still Needed: Non-pressurized boilers will still need a brazed-plate heat exchanger, among other essential components, for proper installation. This list of components can often be just as, or even more expensive than a pressurized boiler and cutting corners here can have devastating consequences to the longevity and effectiveness of the boiler.

However, non-pressurized boilers pose significant risks if not properly maintained:

• Catastrophic Damage: Neglecting to refill non-pressurized boilers can lead to catastrophic damage due to overheating. Without sufficient water, these boilers can reach dangerously high temperatures, causing components to warp, crack, or even rupture. This type of damage is very difficult to repair and may leave the homeowner in need of a new boiler much sooner than planned.

• Increased Fire Hazard: Dry-firing of non-pressurized boilers, caused by insufficient water levels, can lead to overheating of the heating elements, increasing the risk of fire and property damage.

• Voided Warranty: Failure to adhere to manufacturer's guidelines for refilling non-pressurized boilers may void warranties, leaving homeowners liable for repair or replacement costs.

Making the Informed Choice

While both pressurized and non-pressurized boilers offer heating solutions, the risks associated with neglecting non-pressurized boilers underscore the importance of proper maintenance.

Pressurized boilers, with their enhanced efficiency, reliability, and lower maintenance needs emerge as the preferred choice for discerning homeowners and businesses.

Whether you're breaking ground on a new construction project or considering a boiler upgrade, prioritizing safety and efficiency is paramount. With pressurized boilers, you're not just investing in heating technology — you're investing in peace of mind and safeguarding against potential disasters.

PRESSURIZED

• Less erosion
• Infrequent refills and ability to auto-refill
• Not required to use distilled or treated water
• No need for water tests
• Capable of burning unseasoned wood and alternative fuels
• No need for massive storage tanks

NON-PRESSURIZED

• Easier for DIY install (in some circumstances)
• Water levels must be maintained
• More difficult to auto-refill
• Shorter lifespan