ᐅ Limescale Formation in the Combined Storage Tank

Hello esteemed building experts!

Our single-family house has a combined storage tank (750 liters (200 gallons)), of which 200 liters (53 gallons) are allocated to the domestic hot water tank. The energy sources include a wood stove, an electric heating element, and a solar system. The storage tank is used for both the radiators and the domestic hot water.

The 200-liter (53-gallon) hot water section of the combined storage tank is continuously refilled with fresh water. Is significant limescale buildup to be expected in this area? This could at least interfere with the heat exchange between the two storage sections.

To prevent limescale formation, the solar system and the electric heating element only heat the water up to a maximum of 70 degrees Celsius (158°F), which is supposed to help... however, the wood stove can reach 90 degrees Celsius (194°F) or higher.

Question: Is it sensible or necessary to also limit the heating temperature of the stove to a maximum of 70 degrees Celsius (158°F)? Does this really help with preventing limescale? Could someone give me basic guidance on how to maintain a combined storage tank?

You should also limit the heating temperature of the oven to reduce the risk of limescale buildup. However, susceptibility to limescale depends not only on the water temperature but also on the design of the storage tank; for example, finned-tube heat exchangers are less prone to limescale than plate heat exchangers. Water hardness is, of course, also an important factor.

Descaling may be required in cycles ranging from one to five years – with very hard water, even more frequent descaling, less than annually, may be necessary.

How often descaling is actually needed should therefore be discussed with the plumber or heating engineer who also handles the maintenance of your equipment.

I would also reduce the temperature of the wood stove from 90°C (194°F) at this point. Water hardness also plays a significant role here. Maintenance should be carried out every 2 years, but with hard water, it should be done after just one year.

Limescale buildup is quite an issue. In my opinion, it’s not only related to the temperature setting but also to the water itself. I have a finned tube heat exchanger, and I need to perform maintenance on it every year.

I also have a plate heat exchanger and can confirm that rapid and significant limescale buildup always occurs. Maintenance is carried out every 18 months.

I have had the same experience and always wondered where the rapid lime scale buildup comes from. It was only when I turned the oven down that this lime scale formation decreased. So, it is also related to the temperature.