What it means
Vaillant's VWZ AI operating instructions list this as 'Building circuit: Pressure too low'. It is a separate code from F.022 (shown as F.22), which Vaillant also uses for low heating pressure.
What to check, in order
- Check the pressure on the display
Vaillant's operating instructions say it should be 1.0 to 1.5 bar with the system cold. Use the Live Monitor menu to see it.
- Call your installer to top up
Vaillant's instruction for this code is to inform your competent person so they can top up the heating water.
- Look for leaks
Vaillant's fault table entry for low heating pressure (F.022) gives leaks and air pockets as the causes. Check around radiators and visible pipes for damp.
When to call your installer
Your installer should top up and purge the system, then find out why the pressure dropped. Vaillant's operating instructions say that if the pressure drops often, the reason must be found and fixed, and its fault table entry for low heating pressure (F.022) points to a leak, air in the system or a faulty pressure sensor.
Quick answers
What does the Vaillant aroTHERM F723 error code mean?
The water pressure in the heating system has fallen below the minimum, so the heat pump has switched itself off automatically. Vaillant's VWZ AI operating instructions list this as 'Building circuit: Pressure too low'. It is a separate code from F.022 (shown as F.22), which Vaillant also uses for low heating pressure.
Can I fix Vaillant aroTHERM F723 myself?
Easy (about 10 minutes to check). Start with: check the pressure on the display; call your installer to top up; look for leaks. Your installer should top up and purge the system, then find out why the pressure dropped. Vaillant's operating instructions say that if the pressure drops often, the reason must be found and fixed, and its fault table entry for low heating pressure (F.022) points to a leak, air in the system or a faulty pressure sensor.
Is Vaillant aroTHERM F723 worth repairing?
Worth fixing. Topping up gets the heat pump running again. Repeated drops point to a leak that needs finding.
Checked against
Last reviewed October 2026. Manufacturers update their pages, and your manual is the final word. Spotted a mistake? Email contact@appliance-error-codes.com.