The V4073A valve has been designed to control the flow of water in small bore domestic central heating systems, where both radiator and hot water cylinder circuits are pumped. It is typically suited for small to medium sized installations.

The V4073A mid-position diverter valve is normally used in conjunction with a room thermostat and cylinder thermostat to provide full temperature control of a conventional, fully pumped central heating installation. When used in this way, the control system is known as Sundial Y Plan and the components can be connected together using the Sundial Plan Wiring Centre which has dedicated terminations and there is no need for a wiring diagram. An alternative method of wiring is to use the Honeywell 10-way junction box together with the Honeywell Sundial Plans Wiring Booklet.

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.