If you want to add a plate heat exchanger, then you may already be aware that there are a few drawbacks. You will need a pump to move the water around the house. Exchangers also tend to affect the stratification of the tank by moving the water in this manner. There are also some advantages to the plate heat exchanger which you may decide over-rides other considerations.
Higher Flow Rate for Hot Water
One of the biggest advantages to the plate heat exchanger is that it has a quicker supply rate than other types of water heaters, such as the internal coil systems. That can be very important if you have a number of devices which use hot water in the house, such as multiple showers, a dishwasher, a shower, or a bath. Ensuring that a number of people can use hot water at the same time is an important advantage.
Ease of Replacement
Sometimes, the water in your area can have such an effect upon your electrical parts that it reduces them to minerals in a few years. Replacing an internal coil is very difficult, but replacing a plate heat exchanger is much easier, making it ideal for areas with a hard water supply.