IRG Hot Water Circulation Pump: When to Choose It Over ISG

An IRG has the same hydraulics and the same model numbers as the ISG. The difference is inside: the seal and the elastomers are chosen for hot water, so the pump can circulate water from boilers and heating systems. In its standard form the IRG is used for hot water up to about 120 °C.

What we need to know

• The highest water temperature the pump will see, not the average
• The system pressure, because the pump sits in a closed loop and the static pressure adds to its head
• Flow and head at the duty point
• Whether the water is treated, and any additives such as glycol

A real order

Two IRG40-160A pumps with 1.5 kW motors, rated 5.9 m³/h at 28 m, were part of an order we supplied to a machinery distributor, together with larger hot water pumps and cutter pumps for the same site. Small IRG frames like these are typical for building hot water loops.

Find the right frame in the selection table; the IRG uses the same model list as the ISG.