Crimps are metal tubes within plastic insulation, which are flattened using pliers to trap two wires, joining them electrically. These crimps can sometimes be re-opened by using pliers to squeeze together the edges of the flattened tube. This can be done with the plastic in place. If successful it frees the two wires. The plastic insulation may break, in which case the crimp is discarded. A normally-closed valve is closed when no power is being applied to it and needs electrical power to drive it open. Essential in regulating the hot water flow within the central heating system – from the boiler to hot water cylinders, radiators or both, we source motorised valves from industry-leading brands such as: In larger properties, 28mm valves may be used (the 5-wire 3-port V4073A1088 and the 6-wire 2-port V4043H1106). The 28mm V4043H1106 2-port zone valve has a6 th wire, coloured white. This white wire might not be used. In that case it should be made safe electrically.

The V4073A 3-port valve never closes water flow through the valve completely. There is always an open pathway from port AB to port A or from port AB to port B or from port AB to both ports A and B at the same time. It will make it easier when re-fitting it (just remember which end the flex was connected or take a picture on your phone). The powerhead can only fit one way round onto the valve body but if space is tight that might not be obvious. The auxiliary circuit allows several 2-port motorised valves to be used to control separate zones without interacting electrically. Otherwise, if several zone valves were used without auxiliary circuits, and all were connected to the same pump so that the Live wire that opened each valve also fed the pump Live, there would be problems. Only when both white and grey wires are energised (and the valve goes to the Heating Only position) can the orange wire get its 230V supply via the valve itself. (Remember, the orange wire can also get 230V from the cylinder stat if it is calling and a hot water program is on.)The Honeywell valves have a D-shaped top to the spindle but you can also use a spanner on this. If you do this, you must use very little force as it is very easy to shear a spindle or damage the valve internally. When using two 2-port valves, the control system may be known as a Sundial S Plan system or a Honeywell S Plan system. The Honeywell V4043H1106 28mm 2-port zone valve has 6 wires. Five of these wires are the same as 22mm 2-port valve.Green/yellow is Earth, blue is Neutral, brown is Live (or Line) to the motor, grey and orange are connected to the end switch and form part of a separate circuit. The blue wire is the Neutral, N. The green/yellow wire is the Earth wire, E. The white wire is connected to the wire from the room thermostat which calls for heating (radiators or underfloor). The grey wire is used to drive the valve to the Water Off position, in which only the heating port A is open; it closes port B. The orange wire provides a Switched Live (Switched Line) feed to run the boiler and pump.

A normally-open valve is open when no power is being applied to it and needs electrical power to drive it closed. The powerhead or actuator is the electrical section. It’s comprised of a motor and some electronic components and usually has one or more microswitches.The Honeywell motorised valve faults detailed above are likely to apply to most domestic Honeywell valves. A failed motor will prevent the motorised valve from opening but it is not the only cause of a valve failing to open correctly. After years of use, the O rings sealing the valve spindle (or actuator shaft) can fail. When this happens, central heating water will seep past and will corrode the metals. When using a 3-port valve, the control system may be known as a Sundial Y Plan system or a Honeywell Y Plan system. These valves have compression pipe connections, though Honeywell make motorised valves with threaded connections too. How motorised valves are used If the property uses a combi boiler (rather than a heat-only boiler) the boiler will usually contain a diverter valve. In small properties there may be no other motorised valves.