Marine Heat Exchangers will supply or absorb the heat from the condensate seawater circuit depending on the building energy demand. Average operational conditions. Marine Heat Exchangers centre in Barcelona is situated next to the Mediterranean Sea. The Marine Heat Exchangers works by collecting sea water using extraction pumps which is delivered to the engine room situated in the basement floor of the building and passed through a heat exchanger. Marine Heat Exchangers from the harbour is used for the pre-conditioning of shops, restaurants, working areas and special rooms as well as contributing to the ventilation of common areas and the car park.