Revolutionizing pool heating: Combining conventional products with unconventional design

by brittney_cutler_2 | April 28, 2022 11:45 am

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By Tom Soukup

There is great opportunity in the aquatics industry to advance pool heating systems. Key areas in need of improvement include water temperature accuracy; downtime elimination; fuel, electrical and space savings; maintenance reduction; filtration efficiency; component life cycle; system longevity; and return on investment (ROI).

These improvements can be accomplished through proper system design, even if the design is unconventional. More often than not, the author’s company draws on their experience in the hydronic heating industry to create pool heating systems with condensing stainless-steel boilers as well as titanium heat exchangers.There is great opportunity in the aquatics industry to advance pool heating systems. Key areas in need of improvement include water temperature accuracy; downtime elimination; fuel, electrical and space savings; maintenance reduction; filtration efficiency; component life cycle; system longevity; and return on investment (ROI).

However, in certain applications, using conventional pool heating equipment offers the best solution. Pool heaters provide a lower upfront cost per British thermal unit (BTU) of installed capacity compared to boilers.

Ultimately, for the author’s company, the design and control strategies are what makes their systems unique.

Planning for innovation

Direct-fire pool heaters—typically high-efficiency units—are ideal for outdoor bodies of water designed for seasonal use. In these situations, a great deal of heat is required to bring the water up to set point temperature during start-up in the spring. Far less heat is then needed to maintain it during the season. Many of these applications also require the heating system to be installed outdoors. While conventional pool heaters are built for outdoor installation, few boilers have the same capability.

The industry standard approach to an application like this is to install a single pool heater to handle the maximum heat load, which only occurs once each year, during start-up. The main issue with this method is if the unit fails, there is no redundancy, and immediate downtime is the result. There is also a litany of other issues which stem from a conventional approach.

From a hydronic perspective, the author’s company has learned to use the lowest number of BTUs needed to satisfy a call for heat, based on current environmental conditions. Whether the heating equipment is condensing (high-efficiency) or non-condensing (conventional), short run times are the enemy of efficiency and longevity.

Using a single, large unit sized for maximum demand means to maintain set point temperature, the unit will fire frequently, for very short periods of time. Not only is this inefficient and hard on heating equipment, but it can also create unstable pool temperatures.

Taking a multi-unit approach

The desired approach when using direct-fire, conventional pool heaters is similar to when using boilers—to install an array of smaller units and stage them with modern controls. Instead of using a single pool heater, three or four can be installed together, with a total heating capacity just exceeding the maximum load.

When implemented correctly, this method maintains the pool within one degree of set point temperature while providing redundancy and reducing fuel consumption. Through the use of staging controls, the heaters can be operated with only as much capacity online as needed at any given time, and the ability to rotate the lead unit to ensure even run times is provided. This approach also simplifies equipment maintenance.

It is beneficial to install a booster pump to maintain correct flow rate through the system, according to the pool heater manufacturer specifications. A booster pump not only ensures the heat exchangers see a proper flow rate, but it also reduces the load on the filtration pump.

Curating a design

Last year, the author’s company was called out to a homeowners association (HOA) where the pool complex had an existing 1.7 million BTU conventional heater. It required major repairs every season, and management had finally decided fixing the unit was not their best option.

The non-condensing unit was seeing such low-return water temperatures, the heat exchanger was condensing, especially during start-up and shoulder seasons. This had caused major damage to the heat exchanger. The bypass valve intended to raise incoming water to a safe temperature was manually operated, as is usually the case. However, without constant manipulation, these valves do not work as intended.

As with every application, the author’s company conducted an evaluation of the actual heat going into the pool. On this particular project, only 42 per cent of the BTUs purchased from the gas utility were actually conducted to the body of water. Essentially, only 42 cents of each dollar reached the pool, which was a highly undesirable situation.

The HOA asked the author’s company to present a new heater design. Their team began the process by calculating how many BTUs the body of water needed under design conditions. Factors for this calculation included the water temperature upon opening the pool for the season, the desired water temperature, the heat loss for the pool, and the customer’s expected waiting period between start-up and set point temperature.

This specific job required one million BTUs per hour. The author’s company designed and installed a heating system with three high-efficiency units, at 400,000 BTUs each, for a total of 1.2 million BTUs. Each unit had two stages of input: 200,000 and 400,000 BTUs per hour. With staging controls, the system had six stages of input, ranging from 200,000 to 1.2 million BTUs per hour. Firing capacity could be brought online as needed through the controls.

The units used were also 96 per cent efficient, meaning 96 cents of every dollar spent on fuel went into the pool water—a 54 per cent improvement over the original system.

To ensure the heaters were seeing the correct flow rate, a variable-speed booster pump was installed. The pump had a built-in variable-frequency drive (VFD) which was factory programmed for a certain flow rate. The flow rate was overridden to provide a more suitable speed of 189.3 litres per minute (lpm) (50 gallons per minute [gpm]) per heater, for a total of 567.8 lpm (150 gpm).

Adding value

In addition to the energy savings from their engineered solutions, the author’s company also provides a three-year warranty, as well as three years’ worth of start-up and preventative maintenance.

Each system uses a skid-mounted design, with all the components secured on a rack to elevate the pool heaters. The powder-coated rack is also engineered to include pool water and gas piping.

Part of the design process is to make sure the facility has proper gas piping and the correct regulator size. If not, this is corrected. The flow rate and electrical supply are also checked to confirm they are adequate for all the pumps in the system.

Keeping customers happy

After several months, the author’s company checked in with the HOA regarding their heating system’s operation. The system continued to run as intended, with all three units sharing similar run time hours. Pleased with the job, the customer has requested a similar system be installed for their next pool.

Author

Tom Soukup is the principal of Patriot Pool Heating Co., with over 20 years as a hydronic designer and installer. He specializes in high-efficiency and green technology, and brings his expertise to custom commercial work, pool heating, and agricultural projects. Soukup can be reached at twsoukup@patriotpoolheating.com

Source URL: https://www.poolspamarketing.com/trade/features/revolutionizing-pool-heating/

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