Summer Shutdown: How (and when) to shut down your District Heating System

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Have you already shut down buildings’ district heating units for the summer? If not, it's high time to take action as there is great economic potential in shutting down heating systems during summer. In the following, we will explain how to do so and what to pay attention to.

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Summer shutdown is about centrally turning off the heat to the building – and not just on, for example, radiators inside the building.

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Did you know that by turning a few valves, 3–5% of the annual energy consumption can be saved? Large buildings can even save up to 10% by optimising their district heating systems! Furthermore, shutting down your heating system for the summer can also help to improve the cooling of the building and result in savings on electricity costs as well.

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When should you shut down your District Heating System for the Summer?

Typically, summer shutdown happens between 15 May and 1 June. Around September 15th, the heating system is turned on again. However, the ideal shutdown and start-up dates can vary significantly depending on the building's insulation and weather patterns. Hence, it is more accurate to look at the individual building and, based on its heat profile, see when it is optimal to shut down its heating system.

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Below are the two heat profiles for two buildings with very different summer shutdown requirements. The graph to the left shows a building that has a heating starting point of 12.5 °C, whereas the other graph shows a building that has a heating starting point of 18.9 °C. The heating starting point indicates when the building needs heat input to maintain the indoor temperature at the desired conforming level.

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The average temperature indicates the best point in time

As the graphs show, these two buildings have very different needs in terms of when to shut down for the summer and when to turn up the heating again.

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We recommend that for at least two consecutive days, the average temperature is at or above the "heating starting point" before you commence with the summer shutdown. Conversely, the temperature should be below the average for at least two days before you turn on the heating again.

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How Ento helps you determine when to shut down your District Heating for the Summer

If you are interested in seeing when the optimal shut down time for a specific building is, you can find the information in the summer shutdown analysis on Ento. Here you can choose that the average temperature is visible on the graph. When the consumption turns black, it is time to initiate the summer shutdown in the building. The graph does not tell you if the shutdown has taken place, only that it is time to take action.

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How to switch off the District Heating System for the Summer

How you switch off your heating units for the summer can vary depending on your district heating system. Some newer district heating systems shut down automatically, while some cannot be switched off for the summer.

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Steps to shut down your District Heating System:

1. Close the summer shut-off valve – or close the district heating return (note that the return is only closed for the comfort heating circuit and not the hot water circuit)
2. Switch off the circulation pump or put it in summer mode (depending on your pump)
3. Check that the hot water is still open
4. Check on a radiator or heat source that it is switched off properly
5. Once a month, let the circulation pump run briefly

Almost all district heating systems have a summer valve, typically turned a quarter turn to the right. The summer valves may look different depending on your system. You can find the summer valve by following your pipes from where the installation starts. The valve is typically located after a branch, where one goes to domestic hot water, the other to the radiators for space heating. You need to turn the one that leads to the radiators.

If there is no summer valve, you must close the shut-off valve that shuts off the district heating. But be aware that you are not closing the valve for the hot water, but only the heating circuit.

To check if you have closed correctly, feel the pipe leading to your radiators or heat source. If it is cold, you have done it correctly.

Switch off the circulation pump at the switch. If summer shut-off is an option for your circulation pump, it will self-start briefly when needed.

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Be aware of moisture problems during the summer shutdown

Before shutting down your heating system for the summer, make sure that there is no risk of moisture problems that could lead to mold in the building. Ask yourself the following questions:

• Is the building very well insulated?
• Is there ventilation in the building - mechanical or natural ventilation?
• Is the summer particularly cold?
• Is the basement heated to avoid moisture problems (can the basement be heated and dehumidified by other means)?

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Summer Shutdown of Oil or Gas Boilers

If you don't have district heating, it is still relevant to do a summer shutdown of your heating system. Many boilers shut down automatically but if this is not the case, you will need to manually shut off the summer valve and the circulation pump. You can typically set the boiler to produce only hot water by turning it to the tap icon.

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Are you unsure about your buildings' heat profile? We can help you find the best dates to shut down and start up your district heating systems. Book a demo with one of our energy experts or sign-up today and receive your first building analysis tomorrow.

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