Worcester CD24i Hot water for 3 mins then cold

[Maisie's dad]

Hi there

When I turn on a hot tap the red demand light comes on on the boiler but after about 3 minutes the light goes off and the water runs cold. It continues to run. Any ideas please?

 

[tomy]

Does it then need resteing ? if you turn the tap off then back on again does it relight? does the heating work ok ?

 

[Maisie's dad]

Hi there thanks for the reply

yes it does relight when i turn the tap on again

 

[Maisie's dad]

sorry yes the heatings fine

 

[tomy]

is the flow normal out of the hot taps ? what does the pressure gauge read?

 

[Maisie's dad]

Yes flow's normal pressure guage reads 1.5 bar

 

[Maisie's dad]

I had to recharge yesterday using the white plastic key i think some of the rads were losing a small amount of water

 

[tomy]

Depends how old the boiler is , some have a divertor valve and the diaghpram goes on the newer ones they have a flow switch which activates the boiler souds like one of these is playing up. if the heating is ok and it doesnt need reseting it will be one of these depending on the age of it.

 

[jiminblack]

Does it run hot then cold then warms and cools again?

 

[Maisie's dad]

Hi

Yes, runs hot then demand light goes out and it cools. Turn the tap back on boiler fires, light's on then hot for 3 mins then cold

 

[jiminblack]

If it's cycling hot, cold then i suspect w/w heat exchanger.

 

[tomy]

if it was the heat exchanger the demand light wouldnt go out !!! flow swich or diaphragm depending on which it has is my bet.

 

[Maisie's dad]

Thanks for your replies, I'll let you know how it turns out