WHEN SHOULD A PLATE & FRAME HEAT EXCHANGER BE SERVICED?
As a heat exchanger becomes fouled with dirt, debris or scale, often the modulating valve provides additional hot or cold liquid to help compensate for the loss of efficiency of the heat exchanger.
Over time the control valve will continue to open fully. Unfortunately, on the hottest or coldest days, even with the valve fully open the heat exchanger cannot meet the thermal transfer requirements and the situation becomes critical.
Monitoring just the operating temperature provides a false sense of security. Recording the difference in the outlet and inlet pressures provides a more accurate result of the amount of fouling.
Fouling equal to the thickness of a piece of paper represents a 20% loss of thermal efficiency. In addition, the energy cost for pumps increases since the pump must work harder to overcome the increased pressure resistance through the PHE
