The True Cost Of HVAC Scale

What can you, as the facility maintenance manager, do about limescale? Limescale and other water formed deposits can cause major loss of efficiency, increased operating costs, and minimize the life expectancy of capital equipment. But first, as a Facility Manager, how can you tell if your HVAC system is suffering from limescale build-up?

Signs of Increased Cost from Scale Buildup

Some of the symptoms will be gradual because limescale deposits build up over time. But small changes in equipment efficiencies can be a sign of limescale growth. Here are some additional signs that show you need to tackle your limescale problem:

  1. Rising operational costs (including tube or pump failures or the chiller shutting down due to high head pressure)
  2. Increased equipment downtime
  3. Progressively growing heating and cooling energy costs
  4. Poor equipment (boiler, chiller, heat exchanger, or tower) performance, including high head pressures or pump reading more elevated than usual

Rising operational costs

If your HVAC gas or electric bill is rising with no change in facility operational hours, there’s a good chance you’ve got limescale problems. Scale deposits can lead to significant increases in energy costs by reducing the heat transfer surface on both cooling (chiller) and heating (boiler) systems. Consequently, more energy is required to achieve the same level of heating or cooling when limescale fouling is impeding the energy coefficients. Also, the reduction in pipe diameter means your pumps work harder to move the same amount of fluid. This not only increases electricity costs but may lead to premature pump failure. Increased fuel costs mean increased building operating and maintenance costs, which affect the profitability of your business.

Some key findings on the costs of scale are:

  • Energy consumption is increased up to 11% for just 1/16-inch of scale, according to the American Society of Plumbing Engineers
  • Equipment failure rates increase due to scale
  • Scale often necessitates the use of chemicals to counter hard water use. Detergent usage increases by 2-4% percent per 1,000 gallons of water.

Increased equipment downtime

When left to build up inside HVAC components, scale deposits will eventually require removal for the equipment to function. Depending on the amount of build-up, the equipment may experience downtime for days or weeks. This downtime quickly cuts into the operational capability of a building, and if all HVAC systems serving a building are down, the building may have to cease operation entirely until the problem is fixed.

Preventing equipment downtime is one of the most significant concerns of facility managers, yet some may not realize that they need to practice correct preventative maintenance plans on their systems to prevent downtime. Naturally, all equipment will experience some sort of downtime for maintenance, but when equipment downtime sharply increases for cleaning, it may be evidence of a larger scale build-up problem.

Progressively increasing heating and cooling energy costs

Progressively increasing heating and cooling costs can be a reliable indicator of scale build-up inside HVAC components affecting the performance and efficiency of HVAC systems. This is especially true when heating and cooling costs increase despite a relatively stable period of climate and building usage.

Facility managers are certainly in tune with the energy costs that a building accrues. Energy costs are often one of the most significant operations and maintenance budget items that a facility manager is concerned about. If patterns of rising heating and cooling costs show a decline inefficiency, it may be time to clean the system entirely of scale build-up.

Poor equipment performance

Poor equipment performance – like on boilers, chillers, heat exchangers or cooling towers – is often first noticed by monitoring the key performance indicators of your systems. Things like the pump and head pressures should be monitored daily to identify baselines. This way, any disparency can quickly indicate scale issues.

Scale build-up inside the boiler, chiller, heat exchanger or cooling tower may be causing the lack of performance out of the system. Poor equipment performance will not only deliver inadequate heating or cooling results but also end up costing many multiples of the maintenances costs for replacement.

Preventing Scale Build Up

There are different methods for removing limescale build-up. These methods generally fall into two categories chemical and mechanical.

A combination of water treatment programs along with chemical or mechanical descaling is necessary to keep scale in check.

Chemical descalers are fluids which react with the calcium carbonate, sulfate or silica build-up to break it down and flush it out of the system.

Mechanical include using rotary tube cleaning or projectile-based systems to remove scale deposits mechanically. They work to remove the mineral deposits plaguing the tubes of HVAC chillers, fire or water tube boilers, heat exchanger tubes/coils and condenser tubes.

To slow the scale accumulation, water treatment solutions are often employed. Depending on the chemistry of your water source, a water treatment company will come up with the right treatment solution for your boiler or cooling tower. Regular tests and checks are essential to ensure the water is receiving the correct dosage of treatment chemicals. However, no chemical treatment will prevent scale deposits entirely, and so vigilant monitoring of system performance is required.

Next Steps:

If you haven’t been taking preventive action against HVAC limescale, today is an excellent time to start. It is never too late to begin, and you may be amazed by the results you will achieve. While there are many different options on the market today, choosing the right solution for your system is essential.

Get started by maintaining a daily logbook of your system parameters like head pressures, pump pressures, etc. The set up an annual or biannual maintenance cleaning program. This will help you get a handle on your scale problem. Next, get guidance from a reputable descaler manufacturer so you can make the right choices for addressing scale in your facility. With their expertise and products, soon your facility will realize lower running costs and a more efficient HVAC system.

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