The plate heat exchanger consists mainly of different numbers of corrugated stainless steel plates. It is where the energy exchange between the coolant and the hot wort takes place. All the stainless steel plates are pressed together with great force and outside them there are two back plates.
There are some suppliers who make plate heat exchangers entirely out of stainless steel, even including the backing plates. It may seem that this “turnkey” stainless steel equipment is more sanitary for beer brewing, but in reality this design does not make sense.
We all know that carbon steel is much harder than stainless steel. All the inner plates are pressed together with the backing plates, and if they are not hard enough, the backing plates will easily deform under the tremendous pressure. Then there will be gaps between the inner plates or between the inner plates and the back plates. The result is serious and may contaminate your whole batch of beer.