Ideal Icos HE18 - Hot Water too hot

[designerg]

I have a puzzling problem with my heating system.

System comprises of Ideal icos HE18 boiler, Grundfos ALPHA2 Pump, Drayton MA1 Actuator, Drayton HT53 Tank Thermostat.

To cut a long story as short as possible:

I have a system that is generating Hot water that is far hotter than it should be (almost can't put your hand under running water). The tank stat is set to 50ºc, and if I try to turn it a bit lower (up to 5ºc) it just springs back to 50 again. If I turn it a bit lower so it doesn't spring back, it doesn't heat the water tank at all. The Stat on the boiler seems to slightly affect the temp of the water, it makes the temp almost bearable when on the first notch of the dial (however the radiators aren't warm enough for the dead of winter).

Now I know you'll say, 'replace the tank thermostat', but let me tell you what's been replaced...

Started with a new Actuator - it was sticking on M and wouldn't move to W, so radiators were a little warm when just water was on.

After the actuator was replaced we realised the water was too hot and noticed the springing tank stat, also the system header tank was overflowing and had hot water in it (ie system was overheating) - The water may have been too hot before, didn't notice.

At this point we had a leaking hot water tank, which was replaced with a new one and new new HW Tank stat.

Water still too hot and header tank still overflowing - engineer turned up the speed on pump, no difference to water temp but header tank not overflowing anymore.

Replaced HW stat again, and Control Thermistor in boiler. Still the same.

Anyone got any clues where to go next? Is it the boiler? Electrics? What would make the HW tank stat spring?

 

[picasso]

Certainly is an odd one, I would check that the hot water off on both the tank stat and programmer are wired up correctly.

 

[sooey]

Apart from that the water in the cylinder should be over 50C, the usual is 55-60. If you don't want it that hot at the taps use thermostatic mixing valves.

 

[JMGas]

So have you actually changed the 3 port valve body? Or just the actuator? If your valve is passing then your hot water is going to get as hot as your rads, around 70c or higher.

 

[shambolic]

Do you have an electric immerser that's mibbee on by mistake?

 

[designerg]

Thanks for everyone's input.

So to confirm Whole 3 way Valve was changed with Actuator. Immersion is definitely not running (was checked by engineer & if the tank stat is right down, we get no hot water).


I've been doing a bit more observation today -

When the Water is 'On' at the timer panel I don't think the Pump is switching off at all - unless I turn the tank stat down to under 50c, when you hear it click off and pump stops.

Coupled with that, the Actuator is on W or M constantly too.

It really is beginning to feel like a wiring/Control Box (if that's the right term) issue.

 

[picasso]

Check the valve has been installed the right way round, should be B to hot water cylinder and A to heating.