| 摘要 |
The invention is based on an apparatus for heating water, having a heat exchanger which is intended for the water and is assigned to a combustion chamber, and a heat exchanger situated therebeneath for preheating the air to be supplied to the burner; in order, under these preconditions, to exclude a thermal overload of the last-mentioned heat exchanger, the entry to this heat exchanger is assigned a vacuum gauge which allows the burner to become operative only when the prescribed vacuum is operative.
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