Which Outdoor Furnace Is Right for You?
Choosing the right outdoor furnace starts with understanding the difference between hydronic and forced-air heating.
Hyprotherm offers two different approaches to outdoor wood heating. Both can provide reliable heat, but they work differently and are suited to different applications.
Hydronic Outdoor Furnace
Heats Water for More Heating Options
A hydronic outdoor furnace heats water and circulates that heated water through insulated underground lines to the building.
A hydronic system may be a good choice when you want flexibility in how you distribute heat throughout your property.
Benefits of a Hydronic Furnace
- Heats your home or shop
- Can heat multiple buildings
- Can provide domestic hot water
- Works with in-floor heat, baseboard, or heat exchangers
- Can be located farther from the building
Typical Distance
Approximately 30 - 200 feet from the building
The heated water travels through insulated underground lines between the furnace and the building.
Forced-Air Outdoor Furnace
Heats Air Directly – Simple & Efficient
A forced-air outdoor furnace heats air and sends it through insulated ductwork to your home or building.
This can be an excellent option for buildings that already have compatible ductwork.
Benefits of a Forced-Air Furnace
- Heats your home or shop
- Connects to insulated ductwork
- Simple system with no water or pumps
- Great for existing buildings with ductwork
- Fast heat when you need it
- Furnace is typically located closer to the building
Typical Distance
Approximately 15 - 50 feet from the building
The furnace connects to the building using insulated underground ductwork.
Hydronic vs. Forced-Air
The biggest difference is how the heat gets from the outdoor furnace to your building.
| Hydronic | Forced-Air |
|---|---|
| Heats water | Heats air |
| Uses insulated underground water lines | Uses insulated underground ductwork |
| Can heat multiple buildings | Excellent for compatible duct systems |
| Can provide domestic hot water | Simple heating system |
| Works with radiant/in-floor heat | Works with existing ductwork |
| Can be located farther away | Typically located closer to building |
Which System Is Right for You?
There isn't one furnace that's right for every property.
The best choice depends on your existing heating system, the buildings you want to heat, how far the furnace will be from the building, and how you want heat distributed.
Have a home with existing ductwork?
A forced-air furnace may be a straightforward solution.
Want to heat multiple buildings or use radiant floor heat?
A hydronic system may give you more flexibility.
Not sure which one you need?
Give us a call. We'll help you compare the options based on your property.
How Do We Know What Size Furnace You Need?
It's More Than a BTU Number
One of the most important things to understand when choosing an outdoor furnace is that you can't always compare furnace sizes simply by looking at the BTU rating.
Hydronic and forced-air furnaces transfer heat differently, so their ratings need to be considered differently.
Hydronic Furnace Sizing
We Can Measure the Water
A hydronic furnace heats water and circulates that water through insulated lines to the building.
One way to determine the heat being transferred is by measuring:
GPM x Temperature Rise (°F) x 500 = BTU/hr
Because water flow and temperature change can be measured, the amount of heat being transferred can be calculated.
Forced-Air Furnace Sizing
It's a Different Animal
A forced-air furnace heats air and sends that heated air through insulated ductwork into the building.
Airflow and temperature rise can be measured to determine the amount of heat being delivered.
That means BTU ratings between hydronic and forced-air furnaces shouldn't simply be compared side-by-side.
Different systems require different ways of measuring their heat output.
Real-World Example
FLRH-185 Hydronic vs. FLFA-1000 Forced-Air
A hydronic furnace and a forced-air furnace can have very different specifications even when they are being used for similar-sized buildings.
FLRH-185 Hydronic
- BTU Output at 180°: 207,293
- Firebox Capacity: 19.77 cubic feet
- Approximate Heatable Area: 5,182 sq. ft
FLFA-1000 Forced-Air
- BTU Output: 91,000
- Firebox Capacity: 16 cubic feet
- Approximate Heatable Area: 4,375 sq. ft.
The numbers demonstrate why BTU output alone shouldn't be used to compare a hydronic furnace to a forced-air furnace.
What Really Matters With a Forced-Air Furnace?
When selecting a forced-air furnace, there are several things to consider together.
BTU Output
More heat output can be important when heating larger or less-efficient buildings.
Firebox Capacity
A larger firebox can hold more wood and may allow longer burn times between loading, depending on the wood, weather, building, and operating conditions.
Burn Time
Wood type, moisture content, outdoor temperature, thermostat settings, insulation, and building size can all affect how frequently the furnace needs to be loaded.
Square Footage
The size of the building matters, but square footage alone doesn't determine the correct furnace.
Insulation, construction, windows, ceiling height, climate, and desired indoor temperature all affect heating requirements.
Forced-Air Furnace Models
| Model | Firebox Capacity | BTU Output | Approx. Heatable Area |
|---|---|---|---|
| FLFA-1000 | 16 cu. ft. | 91,000 | 4,375 sq. ft. |
| FLFA-2000 | 24 cu. ft. | 135,000 | 6,575 sq. ft. |
| FLFA-3000 | 33 cu. ft. | 165,000 | 8,600 sq. ft. |
| FLFA-4000 | 41 cu. ft. | 205,000 | 10,700 sq. ft. |
Heating capacity and performance depend on building construction, insulation, outdoor temperature, wood quality, installation, system design, and other conditions. The figures above are the listed capacities shown in the supplied Hyprotherm material.
Bigger Building? No Problem.
Whether you're heating a house, shop, garage, farm building, or multiple structures, choosing the right furnace starts with understanding your complete heating situation.
Let Us Help You Find the Right Furnace
Tell us:
- What are you heating?
- How many square feet?
- How many buildings?
- Do you have existing ductwork?
- Do you want radiant or in-floor heat?
- How far will the furnace be from the building?
- What heating system are you currently using?
We'll help you compare hydronic and forced-air options and determine which type of Hyprotherm outdoor furnace may be appropriate for your project.
Call Midwest Outdoor Furnace Today
Let us help you find the right fit for your home, shop, or property.
