3 questions to ask when considering a new commercial boiler
By JOHN KOPF
Property owners and facility managers can realize significant energy savings and improved comfort in a facility or building by upgrading an aging boiler with a new, more efficient unit. A more efficient new cast iron or high-efficiency condensing boiler uses less fuel, and provides more comfort for the building occupants while building owners benefit from years of trouble-free operation.
Condensing boilers have efficiencies typically above 90 percent and exceed the current Department of Energy’s minimum prescribed efficiency levels. Replacing a 65 percent efficient cast iron boiler with a new one that has 84 percent thermal efficiency or higher will result in significant fuel savings, according to the Department of Energy.
Here are three questions specifying engineers should consider when choosing the right boiler for a commercial application:
1. Is it a new installation or replacement?
If the project is a retrofit, the building owner may ask the consulting engineer to determine if it will make sense to change the system from steam to water.
In installations limited to heating, hot water boilers will be more efficient than steam simply because of their lower combustion temperatures, resulting in less energy consumption. Process installations, on the other hand, often require steam for high temperature applications such as sterilization in hospitals. Dehumidification would be another example where steam boilers would make more sense than water. Finally, existing steam systems are much easier to retrofit using one-for-one boiler replacements due to simplicity and lower overall project cost.
At times, customers are sold on the idea of retrofitting steam systems to water systems. This is recommended in situations where the building operating engineer or servicing crew is not very experienced in steam applications and maintenance of these systems. Because of this issue, there are a large number of steam systems that are either underperforming or having frequent breakdowns. The cost of converting a steam system to a water system, however, can be quite high and may result in a long payback.
Another important question for retrofit applications is how difficult is the access to the mechanical room? Some condensing boilers such as the Weil-McLain SlimFit 1000-2000 boiler, offer narrow design (less than 33 inches wide), low height and can be split into two separate sections for easier navigation around tight corners and access to small elevators. Splitting the boiler will reduce the overall weight, making it easier to move in areas with weight limits such as elevators. New construction, on the other hand, has typically greater flexibility when it comes to choosing the boiler.
2. What type of fuel is going to be used (natural gas, propane or oil)?
Natural gas is typically less expensive than propane or oil but it may not be readily available, especially when it comes to rural or remote areas. Oil prices have recently come down and this type of fuel is becoming more attractive and alternative solution to propane.
Does the building owner need a back-up fuel? Alternative fuels such as propane or oil could provide heat when there is no natural gas available. In cases like this, dual fuel burners (gas and oil) offer alternative solutions. Most high-efficiency boilers can be easily converted from natural gas to propane.
3. Is the initial installation cost and longevity of the boiler more important than the overall operating cost or efficiency?
The cast iron (standard efficiency) boilers typically offer lower installation costs, a longer product lifecycle and require less maintenance than condensing boilers. The condensing (high-efficiency) boilers tend to be more expensive but have more sophisticated controls and, under the right operating conditions, can offer higher return on investment. The amount of savings will vary and depend on the application (high temperature vs. low temperature systems), seasonal run hours, utility rates, part load conditions and boiler efficiency.
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