Portage & Main

| BLOG | 

An insight to Outdoor Boilers

Portage and Main manufactures boilers that can utilize different fuel sources such as wood, coal, or wood chips, wood pellets or other bio-mass. The boilers come in various model and sizes and generate varying amounts of BTU’s. We look to size every boiler to the needed heat load for a given application or install.

Portage and Main boilers are designed and built to be installed outside and are fully capable of handling whatever the outdoor elements throw at them. Quality construction and insulation ensure that the outdoor elements have minimal effect on the performance of an outdoor boiler. As an example, if a boiler has collected snow on its roof, then this snow will not melt as a result of any heat loss from the boiler. The snow will remain there until melted from the sun or warmer outside temperatures.

Boiler Operation – conventional boiler

The wood burning boilers are a manual load system that would typically require loading with firewood twice a day in cold temperatures. A boiler system that is adequately sized to its application generally will burn for 12-14 hours on a load of fuel, in colder temperatures. The boilers have minimal electrical components; simply a blower fan and two aqua-stats. The primary digital aqua stat regulates the temperature of the boiler water, and controls the fan operation to re-therm the boiler water temperature when required, to its pre-set temperature. The second aqua stat exists as a redundancy, in the event the first one ever fails, and will shut off the fan system to prevent overheating.

The heated boiler solution is transported into a home or building through a buried insulated line. Once the water is brought into a building, it is distributed through a heat distribution system or manifold. Polypropylene or “pex” pipe is then used to transport the hot boiler water to the different heat zones in the building. The heat from the boiler water is then transferred to heat a given space or room. This heat transfer can occur through various means such as water to water transfers, i.e., using flat plate heat exchangers, which transfer the heat from the boiler water to another water sources such as domestic hot water, pools or spas. Water to air exchanges are done by radiators, baseboard heaters, or radiant floor heating.

 P&M boiler – Main Components

A boiler system will require multiple main components to complete a system. These main components include things such as, Insulated line, circulation pumps. heat exchangers, misc. fittings/pipe and may include various controls for regulating the various zones


Boiler Install Configuration

HSP recommends that each customer complete a review of their heating requirements to best determine the components desired and configuration to use. This is done to determine not only what size of boiler to use, but also what heat distribution method should be employed

Insulated Line

All installs begin with the insulated line, typically the 1″ Logstor Dual Pex Flex insulated line is recommended. This line must be installed in a seamless run to ensure no water penetration issues occur over the lifetime of use. The Logstor Dual Pex Flex insulated line uses two (2) one (1) inch pex lines, ( supply and return) these line have a inside diameter of 1″ inch. Other brands of insulated line may have a 1″ inch insulated line that have an inside diameter of 7/8. As the Logstor Dual Pex Flex have a inside diameter of 1″ inch, it not only allows for a larger flow of boiler solution, it requires specialized fittings or adapters. Each run of insulated line with require four adapters.

For most installs, HSP recommends configuring the system to include a main manifold or header to feed the various zones in the building(s).

Once a manifold is planned the interior runs can then be planned using pex pipe. Based on the use of the manifold, this would mean each zone is fed with a dedicated supply & return line. This will optimize the operation of the system to ensure each zone recieves the hot water it needs to transfer heat to each of the zones.

Heat Exchangers should be reviewed and resulting recommendations should take into account; heat load of zone, preferences or budget of customer, BTU output of heat exchanger ( ensure it is adaquate to meet the heat load, even under less than ideal circumstances – ie feeding a zone with 155 f water.

Circulation Pumps

Typically recommend the use of a mid – sized circulation pump, as the main circulation pump for the boiler system. A grundfos 26-99 or Wasser GPD-25-10SF are midsized pumps which offer variable speed and produce 22-33 GPM/29 Feet of head pressure.
A small circulation pump such as the Grundfos 15-58 or the Wasser GPD-15-6SF which offer variable speed and produce up to 17 GPM/ 19 feet of head pressure. Small circulation pumps are a great fit for a dedicated pump for a in-floor pad or DHW production.
Inhibited Propylene Glycol

Inhibited Propylene Glycol is recommended as part of any boiler solution. The recommended minimum ratio is two thirds 2/3 water to one third 1/3 glycol. Only proplyene glycol is recommended, as it is NON TOXIC. If inhibited propylene glycol is used in combination with DHW production, if a leak occurs no one will get poisoned or die. Further if a customer has a leak and is using ethylene glycol, then any leaks, even outdoors can pose serious risks to humans, small animals or livestock. ( a tablespoon of ethylene glycol can kill a cat).

By using the recommended inhibited propylene glycol, user will benefit from three advantages;

Freeze Protection – level of protection dependant on ratio of glycol used
Contains additional corrosion inhibitors( we can never get enough of those)
Assists with the lubricity of the boiler system, specifically pumps.

Heat Exchangers

Many varieties of heat exchangers exist, typically only limited by budget.

Heat exchangers will break down into one of two categories;

Water to water – transfers heat from one fluid to another fluid, such as Tube & Shell, or Flat Plate heat exchangers.
Water to air – transfers heat from a fluid to air, such as Hydronic radiators, baseboards, wall & ceiling heaters. Some water to air heat exchangers also have convection or forced air fans to aid in the dispersal of hot air.
When reviewing options for forced air heat exchangers, there are several options available;

Hydronic Radiators – come in various sizes and BTU outputs. Hydronic radiators are installed in the plenum of a existing forced air heating system. The radiators offer an inexpensive way to interface an outdoor wood boiler into a conventional force air heating system.
Stand alone Air Handlers – come in various sizes and BTU outputs. These self contained units contain a squirrel cage blower, hydronic radiator and a logic board that manages the variable speed fan and thermostat regulation.
Baseboard heaters, wall or ceiling heaters also offer various options for a water to air heat exchanger.

Managing your boiler

In order to extract maximum longevity out of your boiler, we recommend following a few key areas;

Water filtration: by using a side stream filter assembly, the boiler solution can be filtered down to 10 micons. This will aid in the removing or capturing any particles or sediment. Typical water used in any outdoor boiler can vary in Ph, dissolved solids,minerals, etc. As the boiler water ages some particles will bind tighter to become bigger, the filtration system can capture and remove these. Improving the water quality through filtration can go a long way to ensuring a high quality boiler solution.
Water testing & treatment – Portage and Main offers free testing of the boiler water. We will then make recommendations if anything needs to be added to the water. This can ensure that P&M customers have an optimal water solution in their boilers
Following a regular maintenance schedule along with the annual shut down procedures, will ensure your boiler is clean and in good order.

Portage and Main Logo

About Portage & Main

Our head office is located in Prince Albert, Saskatchewan, Canada. Our dealer network spans North America and we would be glad to put you in touch with one of our knowledgeable agents. Our staff oversees the development of new products, monitors production, designs heating systems, and offers tech support for installers. All our wood furnaces are designed for installation outdoors and deliver wood heat indoors.






(306) 922-1722


Monday-Friday : 8am to 5pm CST

Mailing Address

Courier Delivery

Follow Us

Request Quote