Seasonal changes to shower temperatures explained

Seasonal changes to shower temperatures explained

Paul McGuire, associate channel manager at Mira Showers, looks at how the changing seasons can affect the operation of showers of all types – and how installers can resolve some of these key issues.

As the winter sets in, bringing cold snaps and frosty mornings, at Mira we always see a sharp increase in customer enquiries, complaining that their shower is now no longer as hot as it was in the warmer months.

Cold comfort
We find the largest number of such enquiries are customers with mixer or digital showers supplied by combination boilers. The marvel that combination boilers provide to customers leaves them wondering why instantaneous hot water cannot be delivered at the same temperature and flow rate in the winter, as they’re used to in the summer months. The answer, as we all know, is seasonal effect. The circa 35°C temperature rise which many combination boilers are specified to on the domestic hot water (DHW) side, cannot heat the cold supply to the same maximum temperature when the cold mains supply can be as low as 5°C during the colder months. In this instance, the most a customer can hope for is a DHW supply of around 40°C. With most mixer and digital showers requiring a hot water supply of 55 – 65°C, it’s no wonder that customers are literally left out in the cold.

Go with the flow
There are lots of variables at play here, regarding the kW rating of the boiler in question and the DHW temperature rise they’re capable of at their specified flow rate. The principle remains the same, however, with typical combination boilers ranging from 24-32kW, the 35°C temperature rise is often specified at a given flow rate of 10-12l/min. With modern mixer and digital showers designed to be as free flowing as possible, it’s not uncommon for shower flow rates to far exceed this. On a generous main supply, this problem is then often made worse, as the water is flowing through the plate to plate heat exchanger at a such a rate, the DHW has even less chance of reaching the specified 35°C temperature rise.

Don’t restrict – regulate
Fortunately, there’s a simple solution for this, in the form of flow regulators. Supplied with most mixer and digital showers, flow regulators are designed to be installed on the incoming hot supply to the mixing valve or sometimes on the outlet of some mixer showers, and are designed to regulate the flow rate through the shower. The perception for the customer, of course, is that these devices compromise the showering experience. However, ask a customer with a combination boiler how they increase the temperature of the domestic hot water when they’re washing up or running a bath, and the answer is always: “to reduce the flow from the tap”. Installing flow regulators is exactly the same principle.

flow shower mira

The nature of the beast
The difficulty with this of course, is that it’s how combination boilers works – in fact, any instantaneous hot water appliance! To address this issue, it’s commonplace for our customer service team at Mira to provide flow regulators free of charge for customer and installers enquiring with such issues at this time of year. We would also advocate the installation of flow regulators from the offset where the installation instructions for specific showers stipulate.

Where this hasn’t been done, it’s sometimes easy enough for us to send outlet flow regulators which can be installed easy enough by the customer, in between the valve body and the shower hose. When the appropriate size flow regulator is installed (either 6/8/10 litres per minute), this often resolves the issue by regulating the flow of water down slow enough for the combination boiler to heat it to a sufficiently high temperature to resolve the issue.

Whilst prevention is better than the cure by installing flow regulators from the offset, upgrades in systems from gravity-fed to high pressure combination boiler systems can mean that installing them on the original installation of the shower wasn’t applicable at the time.

Electrics 101
It is essential to keep in mind that flow regulators are not suitable for installation to electric showers and can cause them to overheat and produce unsafe temperatures.

That doesn’t mean to say that we don’t get the same enquiries from customers with electric showers when the weather gets colder. Often, a ‘101’ on basic electric shower operation and what the controls do is all customers require to understand how a slight adjustment to their temperature dial can raise the shower temperature sufficiently. In order to reduce unnecessary calls to installers and manufacturers, we would always advocate an appropriate handover of any shower and its operation with the customer following its installation.

As well as leaving the customer to enjoy their shower, it leaves installers to get to the calls which grow their business, and not those which don’t.


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