Understanding a Boiler

| by Joe Holliday
Understanding a Boiler

Boilers can provide homeowners with an all-in-one whole-home heating and water-heating solution. Homeowners can experience the ultimate comfort, while reaping the benefits of a boiler's energy-efficient technology. And, although boilers have been around a number of years, not everyone is familiar with combi boilers as areliable heating and water-heating option.

What is a combi boiler?

Combination—or “combi”—boilers are a European term used to describe a compact boiler that contains both an open loop domestic hot water output, as well as a closed loop central heating output. 

How efficient are boilers at heating a home?

Modulating condensing boilers are perhaps one of the most efficient and comfortable ways to heat a home.

Boilers can be coupled with baseboard heating or a radiant floor system,which uses a network of hot water tubing to heat the floors.

Do boilers come standard with an efficiency rating?

A boiler's efficiency is measured by an AFUE rating—or annual fuel utilization efficiency. AFUE is a measure of how efficient the appliance is in converting its fuel’s energy to heat. For example, an AFUE rating of 95 percent means that 95 percent of the energy from the fuel becomes heat for the home and the remaining five percent escapes through the exhaust flue.

If a boiler has an AFUE rating of at least 85 percent, it is also ENERGY STAR® qualified. According to U.S. Environmental Protection Agency, ENERGY STAR®-qualified boilers use about six percent less energy than a traditional boiler.

What other pieces or parts are pertinent to a boiler install?

Two other pertinent pieces for installation can include a low loss header (LLH) and proper venting. 

The LLH, also referred to as a hydraulic separator, replaces traditional primary secondary piping, which simplifies installation—down to a matter of minutes.

Some manufacturers' LLHs come standard with ball valves to isolate the boiler. By isolating the boiler, maintenance becomes significantly easier, especially when servicing major components of the boiler, as this allows a contractor to quickly turn the flow off to and from boiler.

The LLH, which helps to balance the flow between the system loop and boiler loop, also:

  • Allows quick isolation of boiler from the heating system for service and maintenance;
  • Simplifies and speeds up installation;
  • Saves labor and materials on site during installation; and
  • Has a compact design, which saves space compared to closely spaced tees.

The second possible need when it comes to installing a high-efficiency combi may be new venting—especially when replacing a traditional non-condensing boiler. There are several ways to vent the boiler and among the safest ways is concentric venting—essentially a pipe within a pipe. In concentric venting, fresh air is pulled in through the outer portion of the two-pipe vent and the center space is for releasing exhaust. A second venting option is a two-pipe installation—one for intake and a separate pipe for exhaust. Each option has benefits and should be considered on a case-by-case basis when installing a high-efficiency boiler.

Have another question about boilers? Leave a comment below.

Topics: Cost of Ownership, Energy Star, Heating & Cooling

Companies: Rinnai

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