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External Gas Boiler


The external gas boiler is the result of deep searches to reach the capacity of a gas boiler to run a heating system installed outside in the cold weather and remaining reliable and efficient as well.

Developped with the Natural Gas Technology Center (NGTC) and PM Bowle inc., the PM Bowle boiler is ETL approved for outdoor operation as low as -40C (-40F).

Mostly made out of stainless steel, the PM Bowle external boiler is strongly built and will last longly. Installed on the market for over 10 years, the boiler has been through severe conditions from mother nature and still remain efficient over the years. Its durable components and the low maintenance required makes the PM Bowle external boiler number one of its category.


The P.M. Bowle boiler is designed for outdoor installation only, along a wall or directly on the roof. This patented unit features a copper winged heat exchanger and a forced draft burner, combined with a premixed air/gas ventilator. Seasonal combustion efficiency attains 84% and NOx emission levels comply with the strictest North American norms. The unit’s main components and housing are made out of stainless steel, for longer life.

The design of the double exit stack ensures safe unit operation. All boiler components and the latest generation silicone nitrate-surface ignition system have been approved for temperatures as low as -40C.


The PM Bowle boiler works either with natural or propane gas for outdoor operation only. It heats up a mixture of glycol and water used to warm up a variety of apparaus such as venting coil, water voil, radiant floor, domectic water etc...

Initialy used for heating unit converison (retrofit on make-up air), PM Bowle team developped reached new markets such as ventilation, plumbing, heating, process, radiation, food, etc....



The PM Bowle external gas boiler helps to save space from the mecanic room. In does not require air supply as an indoor boiler requires. Plus there are no chimney required during its installation. Thus you avoid smoke problem and air vaccuum problems plus fresh air supply chinmey hole.

Its seasonal efficiency of 84% ensures low heating costs.

Low maintenance

Maintenance is quick and easy. The intervention requires a gas licensed technician. A normal maintenance routine is advised at least once a year and the inspection consist of: liquid pressure verification, ignition precision, high limits fonctionality and flame probe verification.


Safety is one of the most important thing with PM bowle. During different steps of the assembly, the external gas boiler is submitted to several tests to ensure quality.

Its well insulated combustion chamber ensures no heat transfer to the boiler cabinet. Thus the casing stays temperate.

Its outdoor installation places gas piping outside. Risks of explosion due to gas leak are then 99% eliminated.

Environnementaly Friendly

Natural gas and propane gas are two clean combustibles. Built with a precise and stable combustion system, the external gas boiler stays clean even after years of running. It is CO2 and O2 tested during the testing process to ensure it meets the North American laws.


PM Bowle external gas boiler installation can be upon a roof or on a sidewall. One big advantage to place it wherever required is certainly the avaibility to place it as close as needed to the heating point.