If you lower the temperature of the water heater too low, you may risk legionella.
Fall is usually the time when you start thinking about electricity prices and electricity bills, often because prices rise. Temperature reduction is often a measure that goes back to the one-way tips.
The Danish website bolius. dk advises its readers to lower the temperature of the water heater to save electricity.
“You can save money if you lower the temperature in the DHW cylinder,” claims the site and has estimated that you can save up to $ 250 a year.
According to our experts, however, there is a measure with marginal effect.
– Many think it’s worth adjusting the temperature of the processor, but it’s wrong, says Lars-Erik Fiskum, research director at SINTEF’s water damage office, to click. no.
– Even though there is an increased heat loss at a higher temperature, this will be marginal. At the other end, the lower temperature in the reservoir means that you need more hot water from the dispenser to, for example, the shower head, which in turn leads to a greater heating requirement in the dispenser. Overall, therefore, the calculation will go almost to zero.
And by decreasing the temperature, you also move into a danger zone for legionella, and that the settings at places such as showers and kitchens no longer match.
No savings effect
This overview does not work
Basically, many hot water heaters are set at 75 degrees from the factory.
– We do this to eliminate the risk of legionella and bacterial growth and because it provides the highest possible tapping capacity at least possible, explains general manager Sigurd Braathen at the manufacturer manufacturer OSO for clicks. no.
And it’s just the last one that is an important factor: the higher the temperature in the processor, the less you need to drain it. The following calculation shows it:
Let’s say you have a 50-liter water tank measuring 30 degrees and has available cold water that holds 10 degrees and warm water that holds 75 degrees.
In short, it means that you need 15.4 liters of hot water and 35.6 liters of cold.
Lowering the temperature in the hot water to 70 degrees increases the water requirement to 16.7 liters, and lowers it to 65 degrees, further increases the demand to just over 18 liters.
So how is the energy requirement? Yes, it will be as follows, given that we replenish the cold water cooler to 10 degrees:
Water temperature in preparation
Water quantity of hot water
Energy needs for fresh water heating in preparation
75 ° C
70 ° C
65 ° C
As you can see, there is nothing to save on lowering the temperature. The only thing that allows you to draw the calculation in the direction of saving is that the heat loss to the surroundings gets bigger, the higher the temperature it is in the processor.
However, according to Fiskum, this is quite marginal because the modern processors are so well insulated.
So, if you want to save power straps, do not start adjusting the settings on the water heater.
May cause problems at the drop points
According to Fiskum, you should not begin to adjust the temperature for the reason that it may have consequences for the mixing ratio at the drainage points.
The trick that can limit water damage to the house
– If you set the temperature in the heater, the temperature of the water that comes out of the luminaire also changes. So if, for example, the shower fixture is preset to 38 degrees at a given setting, this will change and you have to drive and adjust, “he explains..
Fishes elaborate by telling that the water has 75 degrees when it leaves the berth, then mixed with some cold water in a mixer before it is passed on to the pipes.
According to Fiskum’s colleague at SINTEF, Alf Furulund, one should be aware that the modern so-called PEX pipes should not be exposed to continuous temperatures above 70 degrees.
– There is something else with the old copper pipes, there’s no temperature limitation, he says to clicks. no.
Another factor in lowering the temperature in the berth is to increase the risk of legionella.
– You need at least 60 degrees in the wiring system to be sure to kill the legionella bacteria, says senior adviser Jens Erik Pettersen at the Norwegian Institute of Public Health, to click. no. He adds that legionella bacteria grow between 20 and 50 degrees.
Jobs that are “black” and completely legal
– And they live in temperatures up to 55 degrees.
The recommendation in the technical regulations is that the temperature of the water when it comes out of the faucets does not exceed 55 degrees due to the risk of scalding.
In homes where there are small children, the recommendation is that the temperature does not exceed 38 degrees.
To ensure that the temperature at the dump sites does not exceed the recommended temperatures, there is a bowl barrier on the faucet.
If you feel the need to get the water checked for legionella, you can submit a water sample to a laboratory according to Pettersen..
– But these are costly analyzes and in private homes you only need to make sure that the water is at a sufficient temperature.
According to the Norwegian Institute of Public Health, the legionella bacteria die quickly when exposed to temperatures above 70 degrees.
– Do not Buy Foreign Preparers
If considering the replacement of the old water heater with a new one, Alf Furulund should be accustomed to Norwegian processors.
– Norwegian products are adapted to Norwegian water quality. Among other things, they are made of stainless steel, he tells the click. no.
– Something else is with foreign readers. They have a different coating that is more prone to corrosion with the water quality we have.
You can be thrown out even if you own the apartment
So little time you save on boiling water without lid
How to get rid of the laundry quickly
Looking for good interior ideas? You can find them in the Inspiration Guide