FAQ CHECK: BOILER BASICS P.2

Q. What type of fuel should we use?

A. For systems burning only oil, there are three choices — Numbers 2, 4, and 6 oil, the last of which is no longer really viable in New York City where it's being phased out by law (with No. 4 to follow, down the road).

No. 2 oil, which is essentially diesel oil with additives, is the cleanest to burn, but it is also the most expensive. No. 6 is the least expensive, but because of its thick viscosity it has to be pre-heated before burning, and it tends to foul up systems, leading to higher maintenance and equipment costs. No. 4, produced from mixing Nos. 2 and 6, has qualities in between the other two types.

Natural gas is the cleanest fuel to burn. Whether it's more or less expensive than oil depends on the fluctuating market prices for each type of fuel, which can change greatly over the course of a year or several months.

Q. Are there systems that let you switch between oil and natural gas?

A. Something called an interruptible system burns both gas and oil. In an interruptible system, a dual-fuel burner burns gas most of the time and switches to oil only when the temperature dips below 18°F. Utility companies sometimes offer a more attractive rate for interruptible service because it enables them to reduce their required gas load during the cold weather. (The size of the discount varies based on the size and anticipated usage of a particular building.)

If your board opts for an interruptible gas system, you will need to install additional equipment. A new dual-fuel (gas-oil) burner will be necessary, as well as a new gas train, which is a pipe that runs from the utility's gas main (the line coming into the building) to the burner. If the new burner requires high-pressure gas, you may also need to install a gas booster pump. For large buildings with heavy energy usage, the utility may offer a rebate toward the purchase of this new equipment.

Q. Is there any other related equipment our building might need?

A. Because today's boilers are much more efficient than units installed 20 or 30 years ago, a new unit may produce more steam and hot water than the existing heating system is able to effectively handle. A new boiler, therefore, may also require the installation of a boiler feed-water tank to handle the excess condensate that results from using a better-operating unit. The feed-water tank regulates the return condensate back to the boiler to prevent system surges and overflows.

Q. What preventive-maintenance issues should we watch out for?

A. Leaks caused by corrosion can develop over time and affect a boiler's ability to send heat to individual apartments and spaces. Boiler water must be treated with anti-rust chemicals to prevent deterioration to the boiler and distribution system. In addition, asbestos-containing materials are often found in insulation around water pipes and other heating components; their removal will entail an asbestos abatement that can significantly increase the cost and time spent on any heating plant upgrade.

Q. What is the best time to replace a boiler?

A. The best time for replacing a boiler is during warm-weather months, when the building's heating needs will not be as pressing as during the winter. During the eight to 10 weeks on average that it takes to replace an existing unit, your building will need a temporary boiler. (Even during the summer, a temporary boiler will be needed for hot water.) Temporary boilers usually are placed in a trailer close to the building, and the steam or hot water is piped in through a hose connection. Permits from the New York City Department of Transportation and the Department of Buildings will be needed if the trailer is parked on the street. (This is separate from the Buildings Department permit needed to replace the boiler.)

Source: REcampus.com

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