SI 18 30

and SXI 18 30

with CXI 24 30 38

plus C 23

fits CI 24 30 35

and CI PLUS 30

with FLEXICOM SX 18 30

plus FLEXICOM CX 24 30 35

fits ULTRACOM 18 30 SXI

and ULTRACOM 24 30 CX

with ULTRACOM 24  30  38 CXI

plus XTRAMAX HE

fits ULTRACOM 2 12 SXI 18 SXI 30 SXI

and ULTRACOM 2 24 CXI  30 CXI 35 CXI

The pressure relief valve helps to manage pressure build up within a heating system. It is set to proportionally react to increasing pressure in the system to stop pressure building up and breaking the system.