Hot water too hot

[Giles Bee]

Hi,

Completely new to this forum and have a poser that I can't fathom.
We have an Iflo shower that is supplied via a boost pump from our hot water tank.
No matter how low I turn down the temperature at the shower control, the water is always scorchingly hot. The pump appears to be running both hot & cold through it.
When I go to the hw tank there are 2 actuators on the pipes, and one appears to be stuck in position B even when the boiler is off and hw is not required, and a pump appears to be continuously running.
The hot water elsewhere appears to be also hotter than normal, even when I leave the boiler off overnight and don't have hot water heating up for showers etc in the morning.
Is there any way of testing the system to establish which if any of the elements is faulty?

 

[dilalio]

Is your boiler continuously firing when there is no call for either heating or hot water at the programmer?
If the motorised valve for the hot water is stuck open then whenever the boiler is firing, the water in the cylinder (not tank) will continue to be superheated, beyond the cylinder stat setting, giving you scalding hot water.
The temp of this may be beyond that which your thermostatic shower can regulate or that too is defective.
Check/replace HW motorised valve.

 

[Giles Bee]

Hi Dilalio

Many thanks for the reply,

The boiler doesn't appear to be firing continuously however there is a blue Grundfos pump at the hw tank that IS running continuously, even when the boiler is off.

I presume the motorised valve is the white box that has the A & B position on it? One of the black levers on that is very loose and doesn't appear to do anything while the others appear to be stuck.

 

[dilalio]

With both HW & CH off at the programmer, both levers on both white boxes should have resistance and not be 'loose'!
When loose, it means valve is OPEN and will allow flow through.
If the HW valve is stuck open, then even when just heating is on, valve will allow the coil in the cylinder to be heated, thus heating water in cylinder via heat exchange and this will not stop!

 

[Agile]

It also sounds as if your boiler flow temperature is set too high as well.

Perhaps you need a pro?

Tony