Cylinder Stat Help

[Bread]

Hi,

I've been having a problem with my cental heating. It has only been coming on when the water in the cylinder needs heating, ie 1st in morning or evening. Once water has reached a certain temp the CH goes off also.

Anyway after to speaking to a plumber colleague at work today he thought that it would be the cylinder stat that was faulty. He said to take the stat off the tank and that should allow the room stat to call for the CH to come on. So I took off the stat and within a 30 secs the 3 port valve kicked into action and the heating came on

Now my question is does this definitely signify that the cylinder stat is knackered? Also how long is it safe to leave the cylinder stat off the tank?

Thanks

Bread

 

[seco services]

that don't tell me the cyl stats knackered that tells me the orange wire on the 3 port is not becoming live when only heating called for and relying on the hot water call to activate the boiler.

so i'm saying your micro switch in the 3 port is knackered.
you've proved the cyl stat is working by removing it from the cyl and the boiler then fires up.

 

[electronicsuk]

As above. What your colleague at work told you makes no sense. There would be no control at all over the hot water cylinder temperature at all if the cylinder stat was not functioning.

 

[Bread]

Thanks, that makes sense I guess. I will look at perhaps getting the 3 port valve replaced.

I have now put back on the cyliner stat and turned it down to see if it would shut off the CH but as of yet it hasn't closed the 3 port valve, as it normally would once the HW is satisfied?

Sorry, i'm trying to get my head around it but my knowledge is limited

 

[D_Hailsham]

How the mid position valve works

 

[seco services]

if you have put stat back and turned it down so valve has now closed hw port the valve will motor right across to heating only and may of operated the micro switch.
sometimes if the valve spindle is getting sticky they can open but fail to hit the m/switch.