ᐅ Disable hot water recirculation?

Hello dear forum,

What are your opinions on hot water circulation? We have a 145m2 (1,560 sq ft) house with a Vaillant compact system (Auro Compact VSC S 206) including solar. The hot water system is active Monday to Sunday from 5:40 AM to 10:00 PM, with circulation running from 6:00 AM to 10:00 PM.

To save energy, I would prefer to activate the hot water system and circulation only during the times when we actually need hot water. For example,

6:00 AM - 8:00 AM, 3:00 PM - 10:00 PM.

Is this possible, or could it cause issues with Legionella bacteria?

In a single-family home, this should not be a problem. We also turn off the circulation during the day.

baschdieh schrieb:
06:00 - 08:00, 15:00-22:00 hours

Is it possible to do this, or will there be issues with legionella?

There won’t be any legionella problems. You only get those if the water stays too long in the tank, which circulation alone cannot prevent.

Limiting the hot water demand makes sense. In the evening, consider whether it might be better to run the water heating only until 7 or 8 pm (19:00 or 20:00), so the boiler won’t heat up during evening showers or washing, but only the next morning. Turning off hot water demand around midday is especially useful with solar setups, to avoid the boiler activating unnecessarily for minor uses and then the sun heating the water an hour later.

At home, our schedule is from 5:30 to 8:30 am (05:30 - 08:30) and 3:00 to 8:00 pm (15:00 - 20:00). After that, my wife can still use the bathtub without the water going cold. Otherwise, the dishwasher starts at 10:00 pm (22:00) and takes care of the rest.

In a newly built single-family house, circulation can sometimes be turned off completely depending on the location of bathroom and boiler. If everything is stacked or next to each other, the wait time for hot water should be only a few seconds. Just test it and adjust down accordingly. Maybe you have a “self-learning” circulation pump. It memorizes your daily routine and only runs during the times hot water is normally used.
For circulation pumps with integrated time and temperature control, be sure to check the electrical connection. DO NOT run them through the heating system’s controller. Instead, connect them permanently to power—or if connected via the heating system, set the output to permanent ON and not on a timed schedule through the circulation program!

Our circulation pump has a separate power connection and has been connected to electricity for maybe 5 minutes since we moved in 2 years ago.

We have no circulation system and live well without it.

Egon12 schrieb:
our circulation pump has a separate power connection and has probably been powered on for only about 5 minutes since we moved in 2 years ago.

I wrote: Possibly turn it off completely. But IF it is used, it should be controlled by the internal time and temperature settings, not by the boiler. The boiler usually does not have temperature control, so the pump runs throughout the requested period, not just until the water is warm.
Connected pumps also have a program to prevent seizing or similar issues and run for about 10 seconds every 1-2 hours if they have not been activated for a while, depending on the model. In most cases, this is enough to comfortably keep warm water available at all times.