Summer is the best time to consider replacing a chiller for the next cooling season, even if it seems like ages away. Old chillers are one of the biggest energy hogs in a building, and a big ticket item to change when the time is right. Their regular life span ranges from 25 to 30 years based on how well they are maintained and how often they run. If a new one is needed, building managers have to allocate necessary funds in advance to take advantage of the energy savings from today’s more efficient stock.
Make Hay While the Sun Shines
First, you need to determine if it is worthwhile to replace a chiller earlier than originally planned. Ask a consulting engineer to evaluate options. An engineering study typically includes expected replacement cost alternatives, energy savings projections and a life cycle cost analysis. Also consider the condition of the overall chilled water plant, including all pumps, piping configurations and the cooling tower to determine if any modifications or replacements would be worthwhile to perform at the same time.
Reasons to Chill Again
Many older centrifugal chillers operate at full load energy performance between 0.75 to 0.90 kW/ton; however, this performance becomes worse with age. Modern chillers have full load efficiencies ranging from 0.4 to 0.6 kW/ton, as well as vastly improved part load performances. The combination of these improved energy efficiency ratings in today’s chiller technology will have a noticeable impact on the building’s electricity bills.
There are many different types of chiller technologies available in the market, including centrifugal, screw, scroll, modular and magnetic bearing to name a few. Each technology option should be examined by an engineer, based on your building’s noise considerations, energy reduction potential and physical space available.
Chilled Out and Time to Monitor
If you’re thinking about changing your chiller for next summer due to its condition or for energy savings, Ross Morley, mechanical engineer at M & E Engineering, recommends you should temporarily install electrical meters on your chiller to have this data ready for when you apply for incentives. A significant amount of incentives will arise from knowing your existing chiller electrical usage and new chillers’ efficiencies. Currently, local utility companies are offering up to $800 per every kW of demand reduction on the overall building’s electricity bills, which can generally represent a sizeable incentive that may further help justify replacing your chiller sooner.
Monitoring chiller loads now, in the summer, will help an engineer correctly size the new chiller after data is collected. We typically see older chillers that are 20 to 30 per cent larger than the building load requirements. Reducing the size of a new chiller will reduce the overall project cost and increase efficiencies, while meeting the building’s cooling load requirements. A detailed design of the replacement should be started as early as possible because chillers typically have very long lead times of up to 20 weeks, which can delay a project or increase the cost of the project.
Even though parts of Canada have experienced scorching temperatures of 30 degrees plus this summer, now is actually the time to think about your boilers, too. Cold weather isn’t far off, especially for building owners who want to retrofit a heating plant.
That said, the retrofit process should start long before an out-of-date or insufficient system starts to fail. Often, we see clients in emergency situations where maintenance costs can escalate, operational costs increase and replacement parts are difficult to find. Being proactive makes way for time and resources and helps managers and owners consider cost-effective options and incentives involved in the design and construction process.
Hitting a Boiling Point
Boilers require periodic service in order to operate effectively and reliably throughout their service life. Large cast iron or flex-tube type boilers typically last from 20 years to 35 years. The service life of heating plant equipment varies significantly in line with how well it is maintained.
Nick Jackson, mechanical designer at M & E Engineering, says that boilers should be specified according to the specific applications of each building’s requirements. For example, an important decision is whether or not to use a standard efficiency boiler or non-condensing (82 per cent efficient) boiler, a mid-efficiency boiler or near-condensing (87 per cent efficient) boiler, or a high-efficiency or full condensing boiler (95 per cent to 97 per cent efficient). Some designs may use a combination of these boilers in a boiler plant. Costs vary extensively. A standard efficiency boiler is the least expensive and a full condensing boiler is the priciest.
Put the Heat on Planning Ahead
An engineer will design a proper boiler specific to your building that will maximize operating efficiencies and provide the required heat. Condensing boilers require cold inlet water temperatures to achieve their high operating efficiencies. If a design cannot achieve this criterion, then the anticipated energy savings will not be there, and an engineer won’t recommend the expense of such a premium system.
Some boilers have a horizontal configuration with a large footprint, while others feature small footprints, but are tall and need more service clearance. Material types ranging from copper and stainless steel tubes to cast iron and cast aluminum should be selected by your engineer to suit your building’s requirements.
While it’s ideal to meet with an engineer in March or April, summertime isn’t too late to start thinking about a retrofit. This allows optimal lead time to coordinate and plan for the following heating season. Starting as early as possible is critical as boilers can take six to eight weeks to order. Allowing time for a detailed design and tender to be completed will lead to lower installation costs and a smoother retrofit process.
Gas rebates and incentives are available from your local gas companies. As an example, Enbridge offers incentives in the amount of $0.10 per M3 to $0.15 per M3 depending on the scope of the project to encourage customers to conserve energy.
To learn more about chillers and boilers, connect with professionals at M & E Engineering Ltd.: President Ed Porasz, P.Eng., Nick Jackson CET, Project Designer and Project Engineer Ross Morley, P. Eng. M & E Engineering is a professional multi-disciplined Mechanical & Electrical consulting firm situated in Vaughan, Ontario.