Circulator Installation

Always follow the pump manufacturer’ s installation instructions. These instructions will accompany the pump or can be obtained from the pump manufacturer (often by going online and downloading the manual from their web site).

Most circulator manufacturers recommend using their cast-iron models for circulating water in a hydronic space heating system and their bronze models for pumping domestic (potable) hot water.

Never install a circulating pump with operational limits (maximum working pressure and maximum operating temperature) less than those of the hydronic system. Make certain the electrical rating of the circulator is appropriate for the installation.

In residential and light-commercial hydronic heating systems, the circulator should be mounted with its inlet port close to the point at which the expansion tank connects to the return line, which normally is the point of no pressure change in the system. Placing the inlet side of the circulator close to the expansion tank is important, because the latter controls the pressure of the water in the system. The circulator only circulates the water. It does not create pressure. The circulator should also be mounted in the return line as close as possible to the boiler. Install it with the flow arrow on its body facing the boiler. This will ensure that its discharge port also faces the boiler. Never mount a circulator in the highest part of the system.

The circulators used in residential and light-commercial hydronic systems should be installed with their motor shafts in a horizontal position. Installing the circulator with the motor shaft in a vertical position places unwanted weight on the bushings, rotor, and impeller.

When installing a circulator, it is also a good idea to install shutoff valves in the line above and below it. Doing so will allow removal of the circulator without having to first drain the system.

The header piping should be strong enough to hold the weight of the circulator. This can be a problem if it is installed in copper pipe or tubing, because copper has neither the strength nor the rigidity of steel. To prevent sagging from the weight of the circulator, support the header pipe or tubing with metal strap hangers or brackets, or use steel pipe or tubing for the header and connect the copper lines to either end of it.

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