Sunvic SM5203 2-Port Motorised Minival 5 Wire Actuator, Colour May Vary

Straight replacement of SM4203 from the 1980s. The wires are exactly the same. No problem to fit. Make sure the valve runs smoothly and does not bind, otherwise you will need the valve body as well.

Very easy to install. Very quiet. works well.

Replaced a faulty actuator after many years of reliable service. Easily fitted and wired in, worst part was lifting carpet and floorboards to gain access. Quick delivery and fair price.

Works fine

It does what it is supposed to do. A lower price would have made it better.

Precisely what it is described as.Note however that this is not a spring return valve which are more usual to find in modern central heating systems.

As expected. Nothing more nothing less.

My domestic heating system has been using four of these SM5203 actuators with their associated EML 3454 two port valves since 1985. They have proved to be much more reliable than the previous spring-loaded actuators they replaced, and use much less electricity. In the rare event of an actuator becoming faulty it can easily be replaced without needing to disturb any pipe-work.Naturally the moving parts wear out with time, and the gearbox was the weak link with the earlier actuators which only tended to last for about twenty years, about the same life as the shaft seals on the valves. Only one valve in my system tends to expire more quickly but that has double the duty cycle and typically I need to change it every ten years when it begins to leak, however the actuator on it (if still dry) seems to last for a lot longer than this valve.These actuators have two micro-switches inside driven by the cam on the output shaft. These allow for three wire control of the motor; it is only powered when changing position, and once in the desired mode no current is used. Apply Live either to the Yellow wire to open the valve or to the White wire to close it, and the Blue Neutral wire is the return. There is also the bonus of the Orange switched wire to output Live when the valve is fully open, eg for a Pump call. And of course there is also the mandatory Green/Yellow Earth to make up the five. If a sixth wire is needed to output Live when the valve is fully closed then the SM5205 adds this function.The five-core captive lead is just under three feet long.Note also that the picture above shows a different spring-loaded SZ2301 actuator but in a similar shell.