Hotels and Hospitality Facilities: Hot Water Efficiency on Demand
While the amenities offered by hotels and leisure centres can be quite different, the common ground they often share is the manner in which they use hot water. For a hotel, large numbers of customers all wanting a shower first thing in the morning will often be followed by very little need for hot water throughout the day. Similarly, leisure centres may see limited use during the average weekday, before evening fitness classes and swimming lessons create huge demand for showers.
This is before you consider the commercial kitchens in restaurants and hotels, which tend to require continuous demand for high volumes of hot water for catering and washing down. As these catering and washing applications are all related to the preparation of food for human consumption, they are also subject to strict hygiene regulations to ensure that bacteria and legionella protection are safely controlled, and one of the key elements is an effective hot water system.
What is important in all of these environments is that such sudden peaks in demand are accounted for during the design of the heating and hot water system. Commercial buildings may have historically relied upon traditional boiler-based systems for their hot water provision, but these can fail to capitalise on the improved efficiencies, performance, and safety of a more contemporary approach.
The case for instantaneous water heaters
A continuous flow system comprising gas-fired instantaneous water heaters is a particularly strong option in both hotels and leisure centres. This type of system offers a way of delivering a varying flow of hot water at a constant temperature to meet fluctuating demand – crucially, without the need for stored water. As an added boost, the system will only ever utilise energy whenever hot water is needed for showers or wash basins, for example.
With no storage vessel needed, cold water enters the heater and activates a flow sensor which ignites the modulating burner immediately. This then heats up the cold water as it passes through the heat exchanger to a set point of 60°C or above.
The option of being able to cascade multiple units for a larger output makes it possible to achieve flow rates of up to 170 l/min at a 50°C temperature rise, satisfying periods of high demand. This cascade arrangement can then modulate down to the minimum flow rate needed to maintain a secondary circulation system at 60°C. This process of heating the water delivers a constant flow of hot water at the required temperature, and because the ignition process is electronic, there is no need for a standing pilot light, and energy is only consumed to maintain the safe circulation temperature or when hot water is required.
No stored water within the appliance also means the standing energy loss is extremely small, unlike comparable traditional hot water storage systems. This in itself is a huge benefit to commercial stakeholders, who are often faced with the challenge of managing heat losses and energy costs.
The challenge storage-based installations often struggle to overcome is that, if the application requires continuous high demand, the systems may struggle to recover the required temperatures due to the sheer volume of water being drawn off. Using continuous flow water heaters however, a well-sized system can generate the high volumes of hot water required up to temperatures of 84°C.
Mitigating the Legionella risk
As is well-known, the primary method used to control the risk from Legionella in hot water systems is water temperature control. If hot water systems are maintained consistently above 60°C – as they are in the case of instantaneous systems – there is likely to be minimal risk of Legionella growth. However, with older traditional storage systems where there is often a slow recovery, and a high hot water demand, stratification may occur in the storage vessel and it is not always possible to guarantee that all the stored water is maintained above 60°C all the time.
In larger storage systems it is also possible for debris to accumulate at the bottom of the storage vessel, which can then harbour Legionella bacteria insulated from the high temperature water within the vessel and posing a potential risk. One significant advantage of a continuous flow system is that this risk is completely negated.
When it comes to showering, the water which has been heated from cold to 60°C by a water heater will generally need to be blended down to a safe and comfortable temperature of around 40°C. Here, good hygiene regimes and monitoring, as with any hot water system, form a key part of the protection from Legionella.
Whether it is meeting peak demand for showers in hotels or to ensure the delivery of hot water is consistent and at a specific temperature for hospitality facilities, there are undoubtedly huge potential benefits to be achieved through the implementation of a well-sized hot water system. With the installation of a continuous flow system, stakeholders can improve their hot water performance significantly and reduce energy costs, whilst maintaining a strict hygiene regime and reducing the risk of Legionella at the same time.