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Double Wall Heat Exchangers

Traditionally double wall heat exchangers were designed for industrial applications where transfer of heat from one media to another could have dire consequences should the two media ever mix. They are also ideal for homeowners who want to protect their potable water from contamination. Double wall heat exchangers are a viable alternative to the traditional shell and tube, as well as the gasketed plate type designs, which are large and bulky. With a much smaller heat transfer area, they are also capable of much higher heat transfer coefficients which can mean significant savings in terms of the homeowner's initial investment. Their lightweight and small footprint will also mean much lower installation costs.

Design and Construction
Double wall heat exchangers work on the same principle as a conventional plate heat exchanger but is different in that the single plates between the two media are replaced by plate pairs consisting of two identical plates stacked on top of each other and welded around the portholes. The channels then formed by assembling welded plate pairs in a plate pack are conventional channels sealed by gaskets in the traditional manner.

Advantages of Double Wall Heat Exchangers
Due to concerns about cross contamination of potable water, there are strict regulations and guidelines that must be followed to prevent this from ever happening. Double wall heat exchangers offer the best protection against cross contamination. Should any leakage occur, one of the two media will always appear externally and will be easily visible on the outside of the heat exchanger.

Applications of the Double Wall Brazed Heat Exchanger
While there are many industrial applications for these heat exchangers, these double wall heat exchangers are ideally suitable for potable water applications where the possibility of cross contamination must be eliminated. They are commonly used to separate domestic water from other fluids in a hydronic system. They have also been used as instantaneous water heaters to heat domestic water using a boiler. It is important to ensure complete isolation of domestic water from boiler water to protect against chemical contamination of the domestic water supply. In some cases domestic hot water is used as a heating source for radiant floor systems.

In those situations where a boiler is not available, these heat exchangers give you a viable alternative. It is important to isolate a domestic water system from a radiant floor heating system to protect it from bacterial contamination. One bacterium in particular, legionella, has been detected in large concentrations in radiant floor systems. Radiant heating systems, typically operate at roughly 100°F and are left stagnant in summer months. This provides an ideal breeding ground for these organisms.

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