Issue link: http://read.uberflip.com/i/1289816
32 / SEPTEMBER.OCTOBER.2020 USICERINKS.COM MISCONCEPTIONS LEAD TO LESS USE So, following that barrage of details and numbers, with heat recovery in ice rinks clearly a viable option, why has there been a reluctancy by ownership to engage? Many misconceptions and myths still plague the industry. Schematics detailing the installation of heat recovery on refrigeration plants, referring to them as "stan- dard" have been published for more than 40 years. Unfortunately, these misconceptions and concerns are preventing the industry from implementing legitimate cost-reduction systems. In 2020, many contractors who are both competent and well- intentioned, misunderstand or have failed to recognize how important rink heat recovery systems are to the overall sustain- ability of the rink—both environmentally and as a business. This is often ownerships primary and trusted source of information. Some of these common misconceptions or false beliefs include the notion that, simply, "it doesn't work." False. There are laws of thermodynamics and underlying physics that means it does work. Most often this statement is rooted in either an incomplete understanding or a "bad experience" reference. Tunneling into the "bad experience" misconception, this may have resulted in a range of opinions from heat recovery "not work- ing" to "not working well." There is a very significant difference between these positions. The most common reasons for heat recovery "not working well" are based primarily on automation and operation. For example, the belief that heat (for the rink building) is needed in the overnight hours primarily and heat is only available (from recovery) during the operating hours is something called coincidence of loading and, without getting too far into the weeds, automation is always lacking when heat recovery is deemed ineffective based on this objection. Operation also has a significant role on the performance of a heat recovery system to effectively deliver cost reduction. For a refrigeration system operating without heat recovery equip- ment, the discharge (or head) pressure is often lowered to reduce compressor operating costs. When installing heat recovery, it's critical to ensure maximum benefit that the head pressure is increased. This is very contrary to industry doctrine. It is true that when discharge pressure is increased, the compressors will consume more energy. However, it is a very slight increase in comparison to the offset energy from heat recovery. This trade is well worth pursuing. To marry the best of both worlds, install floating head pressure controls with heat recovery to operate at elevated pres- sure (temperature) when heat is being used only. This elevated pressure is well within the manufacturer's ratings for compres- sor equipment. It's merely the pressures realized from operating that equipment on a hot summer day in Texas, conditions that manufacturers have engineered their equipment to withstand. Contrary to the maintenance myth, this will not cause the equip- ment to "blow up". When considering a retrofit (refurbishment) project, it's also usually necessary to install automated valves to ensure proper system operation. RATE OF RETURN Financially, the belief that it is not worth the effort is based on the rate of return realized to any organization. That rate of return needs to be considered carefully. Often, heat recovery is dismissed on the rate of return, while other more cosmetic upgrades and repairs are evaluated without such consideration. The beauty of heat recovery is that once the initial installation is complete, the ongoing maintenance and even eventual refurbishment will be a small piece of the initial cost. Once it's installed and working, it will yield savings indefi- nitely with only modest potential repairs. For example, the primary heat exchanger in a desuperheater installation, which is probably the only component requiring replacement on a 10-15-year cycle, is valued at less than 20 percent of the overall installed costs. Unlike other systems, an integrated heat recovery system will not require periodic tear-out and upgrade like an outdoor condensing unit. Installing a heat recovery exchanger on the refrigeration plant is half of the task. Finding ways to use the heat is the more important part of any system. Obvious choices for heat use include resurfacing water, domestic hot water preheating, snow melt operations and in-floor heating. Slightly more complex uses include dressing room fan coils, lobby fan coils, and/or ven- tilation air heating including part of a dehumidification system. And what's it worth? All of the qualifiers aside, such as how well the recovered heat is used and the cost of the fuel that's being displaced, heat recovery systems produce internal rates of return ranging from 7 percent to 33 percent. Even being on the low end of the benefits, heat recovery from refrigeration systems results in an indefinite cost-reduction in rink operations, with a financial rate of return that dramatically exceeds other financial invest- ment opportunities. J Ian Storey is the president of I.B. Storey Inc., an independent specialty engineering firm that focuses on systems for rink engineering and recreational facilities. , Desuperheater used in the heat recovery process. Heating Up