FAQ - Boilers

What size boiler do I need?

The boiler size needed depends on the construction of the house, the size and type of heating system, the geographical location of the house and the amount of radiation in an existing structure (A detailed heat loss study should be conducted by a qualified heating contractor). The number of people, types of fixtures, number of bathrooms and usage patterns of the inhabitants also determine the appropriate tank size.

My boiler isn't working. I have no heat. What can I do?

Generally it is recommended to:

  • Check that the thermostat is on the "heat" position.
  • Check that the circuit breaker and service switch is in the "on" position.
  • If it is a gas boiler, check that the pilot is lit. If not lit, follow the instructions on the boiler or in the instruction manual.
  • Check your manual to determine if your gas boiler has a vent damper. If so, check manual for its location and put vent damper in "hold open" position. If this works, it is still necessary to have a qualified service technician determine the cause of the vent damper failure and make necessary repairs to reestablish efficient operation.
  • If none of the above correct your problem, call a qualified service technician for assistance.

Does my boiler require maintenance?

Yes, boilers require maintenance. A qualified service technician should perform the maintenance procedure shown in the installation manual on an annual basis.

It is essential that the following is observed at all times:

Keep the area around the boiler free of objects which are flammable or which could obstruct the flow of air into and around the boiler.
Do not store or use sources of hydrocarbons such as bleaches, fabric softeners, paints, cleaners, refrigerants and cat boxes near the boiler. Traces of these chemicals can be drawn into the boiler, causing severe corrosion damage to the boiler and/or objectionable odors.
Do not expose the boiler to large amounts of dust such as that generated by dry wall construction or woodworking.
The owner should visually inspect the venting system on a monthly basis. If any of the following conditions are found, the boiler should be shut down and a qualified service technician called to correct the problem before the boiler is placed back in service:

  • Loose joints, corrosion or other deterioration.
  • Condensate leakage
  • Sags in horizontal runs of vent pipe
  • (JSE Series only) - Blocked vent switch not attached to external draft hood.
  • During the heating season, the owner should also perform a monthly visual inspection of the boiler and the surrounding system piping. To do this, remove the boiler jacket door. If any of the following is found, a qualified gas service technician should be consulted immediately:
  • Deterioration of the visible controls, wiring and sheet metal components
    Water leaks
  • Carbon ("soot") in or near the burner compartment area
  • Carbon ("soot") in or near the burner compartment area is an indication of a potential carbon monoxide hazard. If carbon is found, the boiler should be shut down immediately and inspected by a qualified gas service technician. The cause of the sooting should be found and corrected before the boiler is restarted.

Failure to regularly blow down the float type low water cut-off can result in severe damage to the boiler.

If it is necessary to either manually or automatically add water to the boiler more than once a month, a qualified gas service technician should inspect the system for leaks or defective vents. Frequent additions of fresh water could result in severe damage to the boiler.

Should I be concerned about combustion air?

Both quantity and/or quality of combustion air can affect the safe operation of your boiler. It is necessary to ensure that the boiler is provided with enough clean air for proper operation. For a more detailed explanation refer to your installation manual.

How to determine what type of heating system is installed:

Warm Air Heating Systems - Furnaces:
If the heat in your building is provided by warm air that flows out of ceiling, wall, or floor air supply registers into the occupied space, or if your heating system uses a water-to-air heating system then the air which warms the living space is probably being delivered through large or small diameter ducts, registers, air filters, and a furnace blower, and the air is being heated by a gas, oil, or electric furnace, or perhaps by a heat pump or a geo-thermal system.

Hot Water or Steam Heating Systems - Boilers:
If the heat in your building is provided by warm or hot metal radiators, heating baseboards containing finned copper tubing, or wall convectors that look like a radiator but contain finned copper tubing, or if heat is provided by flexible rubber, plastic, or metal tubing run in building floors or ceilings, then the warm or hot water circulating in those devices are probably being delivered by piping circulating water heated by a heating boiler, or possibly by a steam boiler or a heat pump or geo-thermal system.

What's the difference between a heating boiler and a furnace?

In general, a "heating boiler" heats the building, using hot water. A "furnace" heats a building, using hot air or "warm air." Don't confuse the two since their means of making and distributing heat, their controls, and their equipments are mostly different. For a detailed guide to inspecting and maintaining warm air heating systems or furnaces,

What's the difference between a hydronic (hot water) boiler and a steam boiler?

A "steam boiler" delivers heat to the occupied space in the form of steam: the boiler literally "boils" water and sends steam rising up through steam riser pipes and through steam radiators in the occupied space. If your heating radiators have valves which hiss and let air escape as heat is coming on your heat is probably being delivered in pipes which circulate steam from the steam boiler up through radiators in the occupied space. For a detailed guide to inspecting and maintaining steam heat systems see

How is heating boiler efficiency or economy measured? What does boiler AFUE mean?

Each model of heating boiler is assigned an AFUE number. AFUE is an abbreviation for Annual Fuel Utilization Efficiency. In short, the AFUE tells you, for each dollar you spend on energy for heating by gas, oil, or another fuel, just how much of your dollar shows up inside the occupied space of your building as heat. Higher AFUE is better. If your boiler has an AFUE rating of 90, that means that for every dollar you spend on fuel, 90 cents worth of heat is delivered into your building. The remaining 10 cents is lost in inefficiency such as heat that escapes up the chimney along with the products of combustion.

AFUE is not the whole story of heating cost efficiency. A high-efficiency heating system that has not been cleaned and serviced may be running poorly and wasting money. In fact, an 85% AFUE heating boiler that has not been cleaned might be running at an efficiency much lower, perhaps 65%.

Furthermore, if your building is drafty or poorly insulated, you may be delivering heat at high efficiency but losing it from the building much faster than necessary. These articles can help with a more complete approach to saving money on heat:

What is a Hydronic or "hot water" Heating System?

What are we looking at when we're talking about oil-fired hot water heat? It's helpful to form a simple working definition that helps understand the system. An oil-fired forced hot water or "hydronic" heating system is a collection of components which heat a building by heating and then circulating hot water through heat-radiating devices located in the occupied space.

A "heating boiler" is a steel, copper, or cast iron "box" of hot water, connected to a loop of pipe (and radiators or baseboards) which runs around through the living area. The same physical water stays in the boiler and is circulated by a pump so that heat is delivered to the living area. Burning oil makes hot gases which are used to heat the water before being exhausted outside. Pumps move fluids through the system. Safety controls of various types are installed at various points protect against a number of potential hazards.