hot water way too hot

[northernscum]

i have a RANGE TRIBUNNE HE cylinder and i have turned the cylinder thermostat right down but the hot water coming out of the taps is too hot to put hands under.but before i change the stat was just wanting to see if anyone thinks there could be another fault and not the stat.there is power going to it and it does click when i turn it and the valve at the side opens and closes when i turn it and make it click,and most of the time it is showing the valve in the closed position.the stat is a RANGE TS95H30 with 2 probes going into the cylinder,cant find no info regarding that stat anywhere.any help appreciated.

 

[45yearsagasman]

You need to check that the stat is actually switching.A click is not positive proof.A voltage tester would prove switching and the motorised valve also needs checking for correct operation.Once the stat has opened there should be no power on the (usually) brown wire on the valve.It may also be that the valve has siezed.Theres something to be getting on with.

 

[northernscum]

thanks mate,just gonna get my tester out now and have a look at it thanks

 

[northernscum]

just tested it and when the valve is open there is still power on the brown wire,does that narrow it down?just taken the motor off the valve and it is turning it.

 

[45yearsagasman]

No I meant when the cyl stat has opened there should be NO power on the brown wire.

 

[northernscum]

so if i click the stat to turn it on there should be no power on the brown wire.i have just done that and it went live and the valve opened,if thats what you meant.i have had the hw turned off since i posted but either side of the valve is too hot to hold if thats any useful info.

 

[northernscum]

just an update,turned the hw off at the timer this morning,just got in and the water is still just has hot even though the controller its switched off,could this be the hw motorised valve not closing? any suggestions.

 

[spectralcav]

Sounds like your motorized valve isn't working and stuck on 'open'. You could take off the cover from the power head, turn on the hot water at the controller and turn the cylinder stat up & down and you should be able to see the motor working.

Power heads are normally available separately so you can swap them over without draining the system. Replacement part number should be visible on the casing.

 

[northernscum]

thanks spec,already checked that and its moving ok the motor and also the valve i can turn with my fingers,any more suggestions before i get a plumber out.not had the hot water turned on now since yesterday morning and its still red hot.

 

[spectralcav]

Is there an electric immersion heater fitted to the HWSC?! Seems unlikely, but maybe someone switched it on...

 

[northernscum]

there is one but i have checked its not on,its been ok the water till the last few weeks,since i have started to put the heating higher the water looks like its going with the heating

 

[muggles]

Could still be that the zone valve is passing, if for example the rubber ball has broken up inside it. In this instance you'll need a new one, which may require a drain-down of the system

 

[northernscum]

ok thanks for the help.