Blow down

When water evaporates, substances such as salts or silicates which do not pass into the steam remain in the boiler water. The boiler water in the pressure vessel thus continuously increases in concentration. This concentrated boiler water must be blown down regularly to prevent corrosion and deposits in the pressure vessel.

First condensate is boiler water entrained in the steam that is discharged from the steam pipe in the steam dryer.

Both the blow-down water and the first condensate are pressurised and have steam temperature. In the blow down vessel, blow-down water and first condensate are relaxed and cooled before they may be routed into the waste water system.

The advantages for you

  • High operational reliability through connection to boiler control
  • Utilisation of the thermal energy in the blow down water for feed water pre-heating
  • Cooling water consumption is reduced by utilising the thermal energy and through delayed draining
  • A water level indicator increases operational reliability
  • Reduced-noise blow down possible
  • Good accessibility for maintenance

How it works

Make use of valuable energy and prevent hot water from being discharged into the sewer – here's how it works:

  • Blow down occurs into a water header.
  • In an integrated heat exchanger, the energy of the blow down water and that of the first condensate are transferred to fresh feed water before supply to the feed water container.
  • When the temperature of the water header exceeds a defined value, the water is collected. This uses the energy and voids hot water flowing into the sewer.


We have compiled a number of documents in our Download Centre that provide you with important information about JUMAG's products and services.

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About us

For more than 40 years, we have been developing, producing and selling oil and gas-fired steam boilers.

JUMAG steam systems represent efficiency and user-friendliness.


Jumag Dampferzeuger GmbH
Badener Str. 8a
69493 Hirschberg

+49 6201 84603-0



We are happy to advise you