A calorifier produces hot water, not steam, whilst a steam generator obviously produces steam

A calorifier is a sealed tank, which heats water indirectly. Usually in the form of a heated coil which is immersed in the water. Commonly known as a hot water tank.

A chlorifier is a water tank in which the water is heated via an external source.

The water heater has an electric heating element that is responsible to make the water hot if submerged to water. While the Calorifier is composed of steam coil where the steam from boiler passes through, is responsible to make the water hot if it get contact to the steam coil.

calorifier contains the number of coils through which steam flows.

Steam from steam boiler goes to kitchen,laundry and for calorifier.Around these steam coils,water is flowing which needs to be heated. as u know temp of steam would be more than 100 deg,it heats the water which comes in contact with these coils .

in most of the calorifiers,a set point mechanism is fitted which cuts the flow of steam whenrequired temp of water has attained

Mechanical penetrations (Supply or Return Air Vents) are not allowed in garages in residential construction under the International Residential Code.

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Some countries' Building Codes and/or Regulations may allow a garage to be heated by a normal water-heated radiator supplied by the house's furnace or hot water calorifier. (Calorifier = "boiler" in everyday language.)

To find out if it is allowed where your home is situated you must check the Building Codes and/or Regulations for your locality i.e. Town/State/Country or - better still, as you needed to ask this question here - ask a locally-licensed plumber or HVAC (Heating Ventilation and Air Conditioning) technician for advice.

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Yes you can, as long as you use a 1 way trap tha restricts the airflow only to the garage and not backwards. "International building codes" do not apply everywhere