Halstead boiler CH starts itself when in OFF position.

[philW]

I have a Halstead Finest gold Boiler which starts on it's own when the timer/on/off control on the front is in the 'off' position and when on timer but not timed to be on at that moment.

It seems to stay on (heating radiators) all the time and does not stop. The radiators get super hot, so even some kind of thermostat in the boiler does not seem to work to intermittantly turn heating on and off to stop boiler overheating.

Only way to stop this is to turn off at the mains plug.

There are no room thermostats.

Please can anyone help as to why this happens and what part may need replacing, etc.

Many thanks.

 

[Rob]

If you have a series of LEDs on the front see if the hotwater one is lit. If so you have a faulty microswitch probably caused by a leaking diverter valve.

 

[Agile]

Even if there are no leds then its still likely to be the DHW flow switch becoming faulty or wet.

Simple test is to to disconnect one wire from the DHW microswitch and see if the boiler goes off.

If not then measure the resistance of the two sensors with the boiler cold.

Tony

 

[philW]

Thank you for the replies.

The LED's do not show a seperate one for water, only for when the burner is on.

Therefore, I will check the flow switch and see if there is any water in or around it. Tony, do you know what the resistance should measure when the boiler is cold? If it is higher or lower than what you will say, then does that idicate a faulty switch which I need to replace?

I am not living at my house at the moment, so next time I go there, in a few days, I will check.

Thanks.

 

[Gasguru]

Power off boiler

Lower down controls panel

Hot water switch box is the left one

Remove clip and pull off switchbox.......check diverter pin is not jammed out/leaking

Check pin operates correctly with hot water demand

If pin ok then open up switch box and remove a connnection...check continuity/test switch.

Untitled

• Gasguru
• 10 Aug 2008
• 1

 

[Agile]

Simple test is to to disconnect one wire from the DHW microswitch and see if the boiler goes off.

If not then measure the resistance of the two sensors with the boiler cold.

Tony

Phil, you dont seem to have understood what I asked you to do!

Tony

 

[philW]

Sorry about the delay in getting back.

I checked the hot water switch (left one) and pin works correctly, in and out when asking for hot water, etc. I also checked the other switch (top one) and this pin also does in and out and is not stuck when asking for heat.

I also removed one cable from hot water switch and the heating still stayed on.

I then checked the resistance between the 2 cables is 6.46 ohms when boiler off (hope this is how you wanted me to check it). I also checked when boiler on is 1 ohm.

Please can you let me know what I can check next? Please be explicit when explaining what to do, to avoid confusion on my part.

Many thanks again for your help everyone.

Phil

 

[Agile]

You need to disconnect one lead from the DHW flow switch and measure the resistance across the switch with the boiler power off.

Then you need to measure the resistance of each sensor with the boiler off and cold and the plug disconnected. They are coloured GREEN ! If you are colour blind then there is one pointed out and called "clip" in that photo.

Tony

 

[maxi_byte]

Hi, I have a similar problem. Thanks for the diagram it really helped.

It appears that the connection between my hot water switch and the diverter has rusted and is leaking ever so slightly.

Is this something that can be replaced easily by an engineer? Would it be easy for him to get a hold of the part?

Thanks,
G.