The valve must be positioned where it cannot block any vent or cold feed, when either Port A or B is closed. It may be plumbed in at any angle, but must not be mounted so that the powerhead is below the horizontal level of the pipework. The valve must not be mounted on the return under any circumstances.

If fitted in a confined space, sufficient ventilation must be available to keep the valve within its ambient temperature range and access must be provided to remove the powerhead if necessary.