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Occasionally we come across a Honeywell motorised valve where the powerhead jams but the spindle (actuator shaft) is still free. Where this happens it is usually with the valve jammed open. If all the power to the central heating system is turned off, and the manual lever is still loose across the whole slot, the mechanism may be jammed. We find it is normally about 2.1kΩ (2100 ohms) if the motor is cold and up to 2.4kΩ (2400 ohms) if the motor is quite warm. I think that a reading anywhere between 2.0kΩ (2000 ohms) and 2.5kΩ (2500 ohms) suggests that the motor windings are probably OK. If the reading is many times higher than that, or it is open circuit, the motor has failed. The auxiliary circuit (grey and orange wires) is commonly used to operate the boiler and/or the circulating pump. The auxiliary circuit could be set to work at a lower voltage than mains but it is normally carrying mains voltage. It works like this: One of the two wires, typically the grey, is connected to a permanent mains Live supply (about 230V AC in the UK). The other wire, usually the orange, is connected to the Switched Live feed to the boiler. Sometimes a powerhead is able to drive the valve only part way open but not far enough for the auxiliary circuit end switch to close. This valve will then not be able to tell the boiler to fire.
On older style valves pre-1985, which do not have the replaceable head feature, the adaptor plate assembly can be used to upgrade the valves, to allow the replaceable powerhead to be used.” V4043H1106 is a 2 port, 28mm compression, 6-wire, normally-closed zone valve with an auxiliary end switch The Honeywell V4073A is a spring-return valve. Port A or port B can be closed by a rubber ball, though never both at the same time. The rubber ball is moved between ports A and B by an actuator shaft or spindle which is driven by the powerhead. The inlet port AB can never be closed; the ball only moves between port A and port B. Seized motorised valve spindle in an old Satchwell Sunvic 2-port motorised valve. The water leakage has caused white oxides to form round the brass spindle, making it too stiff to turn The orange wired motors are less robust. I have had several jobs since where customers complained about regular replacement motors on s plan systems, so I replaced with blue wired and had longer stints between subsequent replacements. Basically you will get 5 years plus from a blue wired motor, but only between 2-5 years on an orange wired motor - anecdotal evidence only, so don't hold me to this, but it seems the honeywell guy was telling some truth in my experience.
As we’ve said above, Honeywell make a large range of motorised valves. The Normal state of a valve is the de-energised state. This is the state when no electrical power is being used by the valve motor. Much of what we describe also applies to ACL Drayton motorised valves like the Drayton 2-port ZA5/679-2 22mm zone valve and the Drayton 3-port MA1/679 22mm mid-position valve. Iflo motorised valves and British Gas motorised valves have similar faults. It may also apply to the Tower VAL222MV motorised valve, the Siemens CZV222 motorised valve and the Flomasta 27900SX motorised valve. Where two 2-port motorised valves are fitted (one for the heating circuit and one for the hot water cylinder circuit) the fault may be disguised. Even though one valve only partly opens itself and is unable to fire the boiler, the valve on the other circuit can open fully and fire the boiler. The pump then pushes heated boiler water through both the open valve and the partially open valve.
Honeywell say that the manual lever located on the end of the powerhead is not a position indicator and should be used used for filling the system and for draining down only. Honeywell make a large range of motorised valves used in domestic central heating systems. The most common by far are the 22mm 3-port, 5-wire, mid-position valve and the 22mm 2-port, 5-wire, zone valve. These 22mm valves (3-port V4073A1039 and 2-port V4043H1056) are used in smaller and medium sized properties. A Switchmaster Midi 3-port valve body with a seized spindle. This motorised valve was also rusting through round the screw in the picture Honeywell powerhead (actuator) jams? If Hot Water is then satisfied (either by the programmer or cylinder stat), the grey wire is energised. As there is still a demand for Heating, the valve will motor to the Heating Only position (port A open; port B closed) and switch a 230V supply onto the orange wire, to power the boiler. Inside a Honeywell V4073A 3-port motorised valve showing the rubber ball which closes one or other port, never both.That noise and that bump are diagnostic. They tell us that the valve has moved into the mid-position where both Heating and Hot Water ports are open. If you can make a Honeywell 3-port mid-position valve move into all three of those positions, the valve and controls appear to be wired correctly and the valve appears to be working normally. A normally-open valve is open when no power is being applied to it and needs electrical power to drive it closed. 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. The Honeywell V4073A 3-port valve has five wires. These are blue, green/yellow, white, grey and orange. Note that the grey and orange wires are used differently from the grey and orange wires of the 2-port valve!
If the powerhead (actuator) can be safely removed from the valve body (see warning above about pre-1985 Honeywell valves) you can try to turn the spindle. You may need a tool unless you have strong fingers. You must also isolate the electrical supply before removing a Honeywell motorised valve powerhead.
The Honeywell motorised valve faults detailed above are likely to apply to most domestic Honeywell valves. V4043H1080 is a 2 port, 1” BSP Female threaded, 6-wire, normally-closed zone valve with an auxiliary end switch When the programmer and stat send a Live feed to the 2-port motorised brown wire, the motor drives the valve open to allow water to pass. When the valve is fully open, the end switch closes, allowing electrical current to pass from the grey wire to the orange wire and from there to the boiler Switched Live. Unless the boiler thermostat is already up to temperature, the boiler will now fire. With modern boilers, the boiler sends a Live feed to the circulating pump which then pumps heated boiler water through the valve. It will go to the radiators or to the cylinder coil, depending on which valve was opened. With older boilers, the Live from the auxiliary circuit end switch goes directly to the pump at the same time as it goes to the boiler Switched Live. 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.
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