Warm water from hot water cylinder.

10 Jul 2010
Reaction score
West Midlands
United Kingdom
Can anyone please help? The hot water from my cylinder supplied from my boiler has gone luke warm. The pipework before and after the motorised valve is hot before it goes into the hot water cylinder. The central heating is working fine. I have a conventional boiler Suprima, the Cylinder is Supercal 3 vented cylinder. The water in the cylinder gets no hotter than 30 degrees. If I turn the thermostat lower I can hear a click from thermostat and I can hear the motorised valve turning off.
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when you turn the stat up do the pump and boiler, after about ten seconds, start up?
Cylinder stat was set at 60 degrees. Turned it up to 90 but it made no difference to water temp.
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Hello Mick
Sorry what do you want me to put thermostat temp. on initially. At the moment it is clicking on about 25 degrees. It is the strap on type.

OK turned thermostat right down, turned hot water on and waited. Nothing then turned thermostat up and like you said Mick, after about 10 secs, pump and boiler and myson control valve all operated fine.
is there any heat going through the coil on the cylinder?
is the heating turned on?
is there a vent on the coil that needs bleeding?
The hot water pipe going into the middle of the cylinder coming from the motorised valve is really hot.
No the central heating is not turned on but that works fine.
There is a small bleed valve on top of the pipe which fits on top of the hot pipe which I have bled and a small amount of air came out.
thanks for replying.Paul//media.diynot.com/146000_145091_27827_37812100_thumb.jpg
I have done 2 things and one appears to have worked. I took the thermostat off the cylinder and laid it on the floor, and I have bled a bit of air from the hot pipe and now the water is hot. I am curious to know which has worked ???
If you replace the cyl stat and it stops working you'll know the fault lies there, if still ok the air was most probably the cure.

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