Sports, Stadiums, and Showers - The science of sizing hot water systems

Kevin Potter, our Business Development Manager for Hot Water, takes a look at the special requirements of sizing hot water for sports facilities, from grass roots to world renowned stadiums.

Probably the most important question to ask when sizing hot water for any building, but even more so for sports facilities, is - what is it being used for?

Stadiums are actually fairly simple to size hot water for the players. You will only ever have two teams in the changing rooms at one time. So it is more about the comfort of the spectators. There will be inevitable peaks in hot water demand pre-, middle-, and post-match on the catering facilities as well as the toilets/wash basins, but this allows time between peaks for recovery of hot water.

However not all sporting facilities are as easy. Up and down the country there are hundreds of sports centres, pitches, University facilities, schools and village greens that vary in size, use and demand.

A scrum for the showers

Kevin Potter explains why it’s not just the number of people using the facility that affects the hot water sizing but the type of sport being played. He says,

“People who play sport inside, use the gym or attend a fitness class may not shower on the premises. However, players of sport outdoors generally shower soon after the match has finished due to the dirt or cold. But even two outdoor sports will have differing shower requirements. Comparing Hockey, which is often played on an artificial pitch, with Rugby which is played on grass. Due to the nature of the game, rugby players get covered in mud meaning they will spend longer in the shower compared to Hockey players using an artificial pitch. All these factors will affect the choice and size of hot water system.

“The type of shower that is installed also has an influence on hot water use. A push button which turns off after 20-30 seconds will use less water as people are quicker and waste less. Whereas on/off showers are often left on between players showering. One shower running continuously for one hour can dump 328 litres of hot water (at 50°C with a flow rate of 9 l/min).

“Plus, you wouldn’t believe the amount of changing rooms that are poorly heated so players use the steam and heat from the showers to warm up the room when they are not showering. Again, this all needs to be factored in to the water heater sizing calculation.”

Trying to tackle the numbers

To size hot water for the facility you need to take a combination of the initial dumpload plus recovery, generally a worst-case scenario. This means determining the duration of continuous use, which will depend on the maximum number of showers (not physical units but showers being taken by players/customers) and the period of time they take place in. This will give you the peak load. You then need to factor in hot water storage requirements and back up/maintenance options.

Converting the load

Hot water storage requirements for sports facilities tend to be larger due to all hot water being drawn off at once. But you must consider the larger the storage the longer it takes to recover. Undersize and you won’t have enough water to meet demand, resulting in unhappy customers. But oversize and it will take longer to heat up, increase costs and waste energy. It is a balancing act between continuous output, storage and recovery. Once all this has been weighed up you can then begin to match the load requirements to product and hot water system selection. 

Kevin Potter concludes,

“Hot water sizing is not an exact science and often requires some guess work based on assumptions as well as historical and projected usage figures. Asking all the right questions and understanding the priorities of the client from the outset can help get the most accurate picture to work from.

“Once a demand profile is established you can review this against the available hot water heaters, taking into account building and budgetary constraints.”

For advice on sizing hot water systems attend Hamworthy’s CPD seminar on Hot Water Best Practice. I would like to attend your CIBSE-accredited CPD.