Abstract: A transfer valve having a valve casing with a closed bottom, a closed top and a separator plate dividing the interior of the valve casing into an upper chamber and a lower chamber. An inlet port opening into the upper chamber, an outlet port opening into the lower chamber and two additional ports opening into both the upper chamber and into the lower chamber. A valve in the upper chamber and a valve in the lower chamber, and a control rod extending through the upper and lower plates to simultaneously rotate the valve from one of the additional ports in the upper chamber and in the lower chamber to the other additional port in the upper chamber and in the lower chamber.