• Replaces Honeywell V4073A: Like for like swap for a V4073A or V4073A1039 mid position valve, matching its dimensions, spindle pattern and wiring
• Y Plan heating and hot water: Three port diverter design directs flow to the radiators, to the cylinder, or to both circuits at the same time
• Mid position action: Sits part way between the two ports so the house and the hot water cylinder heat together rather than in turn
• Powerhead included: Supplied complete with the motorised actuator fitted, so the valve arrives ready to wire in without buying a head separately
• Boiler and pump switching: Runs from a 230 V AC supply and carries an auxiliary switch that fires the boiler and pump once the valve has moved
• Manual lever: Holds the valve open by hand for filling, venting or commissioning, then releases back to automatic operation

The LavaTherm 3 Port Mid Position Motorised Valve is a 22 mm three port valve for controlling both the heating and the hot water circuits of a domestic wet central heating system from a single valve body. It is the standard valve used in a Y Plan layout, the most common control arrangement in UK homes with a vented cylinder.

Unlike a simple diverter, a mid position valve has three working states. With a call for hot water only, the valve stays in its rest position and flow passes to the cylinder coil. With a call for heating only, the actuator drives the valve fully across so that flow passes to the radiator circuit. With a call for both, the valve holds a mid position and feeds the two circuits at the same time, which is what allows a Y Plan system to heat the house and the cylinder together rather than one after the other.

The valve is supplied complete with its 230 V AC motorised actuator head already fitted. An auxiliary switch makes once the valve has moved to the calling port, firing the boiler and pump. A manual lever holds the valve open for filling, venting or commissioning.

The actuator head is a separate assembly held on the valve body by two screws, so a failed head can be replaced on its own without draining the system or disturbing the pipework. Replacement LavaTherm actuator heads are available separately.

Suitable for installation by a competent heating engineer. All electrical work must be carried out in accordance with current wiring regulations.

This valve is a like for like replacement for a Honeywell V4073A three port mid position valve. It matches the original on body dimensions, spindle pattern and wiring, so it fits the same position in the pipework and connects to the same wiring centre terminals.

Because the valve wires terminal for terminal into a standard Y Plan wiring centre and matches the V4073A footprint, it fits straight into the space and wiring left by the old valve, keeping the repair quick and predictable.