Multi Pass Series – Affordable Outdoor Stoves

MULTi Pass series
Traditional Furnaces. Advanced Technology.

Outdoor Coal Furnace

The Multi Pass outdoor boilers combines the proven design of a traditional outdoor coal furnace with technology engineered for greater efficiency and cleaner combustion. Built with 409 Titanium Enhanced Stainless Steel, each furnace features a triple-pass water-filled heat exchanger, Turbo Draft System, and cast iron shaker grates with a removable ash pan for efficient heat recovery and easy maintenance.

With multiple models and heating capacities available, the Multi Pass Series provides dependable outdoor heat for homes, shops, garages, barns, greenhouses, commercial spaces, and other applications.

409 Titanium Stainless Steel

The firebox and water jacket are built with 409 Titanium Enhanced Stainless Steel for excellent corrosion resistance, heat transfer, and strength in the high-temperature gasification environment.

Triple Pass Heat Exchanger

The triple pass system directs combustion gases through multiple passes to maximize heat transfer and recover more usable heat. Stainless steel heat exchanger tubes support efficient heat transfer while helping facilitate secondary combustion, resulting in higher efficiency and lower fuel consumption.

Turbo Draft System

The turbo draft system allows for a cleaner, more efficient burn inside the firebox while permitting secondary gases to be burned before escaping out of the furnace chimney.

Stainless Steel Chimney

A durable stainless steel inner and outer shell provides long-lasting performance. The insulated, double-wall design allows for easy expansion with interlocking chimney lengths.

Water Level Indicator

An easy-to-read water level indicator helps you quickly monitor the furnace and know when additional water is needed.

Digital Control Panel

Easy-to-read digital controls help maintain consistent heat while making it simple to monitor and adjust furnace operation. The illuminated display is easy to read day or night. They are also economical and easy to replace.

turbo draft system

Maximum Efficiency. Cleaner Burn.

Our Turbo Draft System delivers controlled air flow throughout the entire firebox, creating higher temperatures and a more complete combustion. The result is more heat, less fuel, and lower emissions.

Secondary combustion for cleaner, more complete burn.
Turbo charged air flow for maximum heat extraction.
Lower fuel consumption and reduced emissions.

multi pass models

7200mp

multipass series

Approx. btus 165,000

Approx. area 2,000-3,000 sq.ft.

Water capacity 140 gal

Firebox length 30 in

Weight 1,450 lb

Epa certified – no

7300mp

multipass series

Approx. btus 275,000

Approx. area 4,000 – 6,000 sq.ft.

Water capacity 180 gal

Firebox length 38 in

Weight 1,800 lb

Epa certified – no

7350MP

multipass series

Approx. btus 350,000

Approx. area 6,000 – 8,000 sq.ft.

Water capacity 260 gal

Firebox length 44 in

Weight 2,050 lb

Epa certified – no

7400mp

multipass series

Approx. btus 400,000

Approx. area 8,000 – 10,000 sq.ft.

Water capacity 320 gal

Firebox length 48 in

Weight 2,500 lb

Epa certified – no

7500mp

multipass series

Approx. btus 750,000

Approx. area 18,000 – 20,000 sq.ft.

Water capacity 600 gal

Firebox length 60 in

Weight 4,000 lb

Epa certified – no

applications

Residential Homes

Commercial Spaces

Greenhouses

Barns & Agricultural

Heat your home with a Multi Pass centralized outdoor furnace while keeping wood, ash, smoke, and debris outside.

Heat medium-to-large size commercial buildings and facilities with a properly sized Multi Pass furnace.

Use the Multi Pass furnace to support temperature control and maintain consistent temperatures in greenhouse applications.

Provide heat for barns, livestock buildings, and other agricultural spaces with the Multi Pass series.

Domestic Hot Water

Garages & Workshops

Hot Tubs & Pools

Radiant In-Floor Heating

The Multi Pass outdoor furnace can provide heat for domestic hot water when properly installed and equipped.

Comfortably heat detached workspaces, garages, and workshops with the Multi Pass outdoor furnace/boiler.

Use your Multi Pass outdoor furnace as part of a properly designed hydronic system for heating pools and hot tubs.

Deliver consistent hydronic heat through radiant floors in homes, shops, garages, and other buildings with the Multi Pass Series.

Frequently Asked Questions

The Triple Pass Water-Filled Heat Exchanger forces hot exhaust gases through three separate passes before exiting the chimney. This allows more heat to be transferred into the water jacket instead of being lost through the exhaust, improving efficiency while maintaining strong heating performance.

The Multi Pass Series is designed to burn coal and other biomass fuels, offering flexibility for different heating needs. The Pristine Series uses advanced gasification technology and is engineered specifically for burning seasoned cordwood with maximum efficiency and low emissions.

The Multi Pass Series is designed to burn coal. Always refer to your owner’s manual for a complete list of approved fuels and follow all operating guidelines.

The Triple Pass Water-Filled Heat Exchanger is designed to capture more heat from the combustion process, helping maximize fuel efficiency while delivering dependable heating performance.

Fuel consumption depends on the size of the furnace, outdoor temperatures, your heating demand, and the type and quality of biomass fuel being burned.

Routine maintenance includes removing ash and periodically inspecting the heat exchanger and chimney. Cleaning frequency depends on usage and the type of biomass fuel being burned.

Yes. Electricity powers the blower, circulating pump(s), and electronic controls that regulate furnace operation.

Yes. When installed with the appropriate heat exchanger, the Multi Pass Series can provide domestic hot water while heating your home.

Yes. The Multi Pass Series can often be integrated with existing forced-air furnaces, boilers, radiant floor heating systems, and other hydronic heating systems. Your local dealer can recommend the best installation for your home.

For the best performance, use clean, dry biomass fuels that are approved for the Multi Pass Series. Following the recommended fuel guidelines helps maximize efficiency and extend the life of your furnace.

The Multi Pass Series is built from domestically sourced 409 Titanium Enhanced Stainless Steel for exceptional durability, corrosion resistance, and long service life.

The Multi Pass Series is backed by a 20-Year Limited Warranty, providing long-term confidence in your investment.

Yes. With properly sized insulated underground piping, one furnace can heat multiple buildings, including homes, shops, garages, barns, and other structures.

With proper installation, routine maintenance, and regular care, a Multi Pass furnace is built to provide many years of dependable heating.

Loading frequency depends on the outside temperature, your heating demand, and the type of fuel being burned. Coal typically provides long burn times, helping reduce the frequency of refueling compared to some other solid fuels.

Crown Royal Stoves recommends removing ash from the ash pan weekly and the heat exchanger every 2-3 weeks. The less ash in the Heat Exchanger the higher the efficiency.

Depending on the fuel type and heat demand, typically you should shake the grates once a week after a coal bed is established.

Both the Multi Pass and Pristine series are designed for 12 hour burn times when sized appropriately. Speak to your local dealer for accurate sizing of a unit. A site visit may be necessary to size a unit appropriately.

All Crown Royal Stoves come with a preset temperature set point of 180 Degrees F with a 10 degree differential. Optimum fan speed for the Multi Pass stove is in the medium to low range as indicated at the rheostat fan speed controller. All coal varies in quality. Most of our customers have found the greatest success with a temperature set point of 180 degrees F with a 1-2 temperature differential, and the fan speed as low as possible to still ignite the coal bed while not blowing out the fire in the coal bed.

The two types of coal recommended to burn in your Multi Pass stove is anthracite and bituminous. Anthracite: also known as hard coal. The highest quality of coal. It is a hard, brittle, and lustrous black coal. Anthracite burns hotter for longer periods of time producing the highest BTUs of any other type of coal. It is also the cleanest burning type of coal. Bituminous: also known as soft coal. Bituminous coal is a middle rank coal between subbituminous and anthracite. Bituminous usually has a high heating (BTU) value. There are different grades of bituminous coal, some that have higher sulfur content than others. Bituminous coal appears shiny and smooth when you first see it but look closer and you may see it has layers.

The best size coal to burn in your Multi Pass stove is Nut coal (13/16’ – 1 5/8” Diameter), Stove coal (1 5/8” – 2 7/16” Diameter), and Egg coal (2 7/16” – 3 1/4” Diameter).

Yes, as long as a good size coal bed has already been established using smaller sized coal. You may find that smaller coal may burn easier.