Sunvic Actuator & Valve question

[CPCUK]

Hi,

The other night we heard a buzzing sound coming from our airing cupboard. It turned out to be the Sunvic actuator SM3201.

Basically by removing the actuator from the valve body (Sunvic 2-port ML3501) I figured out that the motor seemed to be working and did turn the small spindle (tongue) piece which fits over the valve. However, I tried to manually turn the valve spindle itself and it was very hard to turn. I managed to free it up and it now turns by hand with a fair bit of pressure.
The CH and the hot water is working fine and I believe this is because the Sunvic valve is in the OPEN position permanently.

Our local plumber changed the Sunvic thermostat for a digital Honeywell thermostat about 6 months ago when he did some work for us. He drained the whole system at the same time.

I have 5 questions and they are as follows;

1) Should the valve spindle turn very easily with very little force?

2) The Sunvic actuator has been replaced by a different model now and this can be seen on the Sunvic website. Which model would you recommend to fit should the actuator be too weak to drive the valve spindle (SM5201 or SM5203)?

3) If the valve body itself requires replacement then does this mean the only option is to drain the whole central heating system?

4) As the valve is OPEN all day and night could this damage the boiler in anyway?

5) I guess our heating bills will be higher than they should be if the valve is left OPEN and isnt replaced, correct?

Any help greatly appreciated.

Thanks,
Chris

 

[Softus]

1) Should the valve spindle turn very easily with very little force?

Yes.

2) The Sunvic actuator has been replaced by a different model now and this can be seen on the Sunvic website. Which model would you recommend to fit should the actuator be too weak to drive the valve spindle (SM5201 or SM5203)?

If the spindle is stiff you need to change the body, not the actuator.

3) If the valve body itself requires replacement then does this mean the only option is to drain the whole central heating system?

It isn't the only option, but it has two overriding advantages:

1. It's the easiest option.
2. It allows you to assess the quality of the water by watching it as it drains out.

4) As the valve is OPEN all day and night could this damage the boiler in anyway?

No.

5) I guess our heating bills will be higher than they should be if the valve is left OPEN and isnt replaced, correct?

At this time of year, not necessarily, because you'd have the heating on anyway. With the head removed, the heating will come on when you've programmed it, but also when the hot water is being heated.