Ideal he24 boiler No DHW

[mm915]

Hi, everyone

I'm struggling to find the answer to the problem I'm having, The boilers CH works absolutely fine. The issue I have is the boiler will not produce hot water on demand.

When a hot tap is turned on the boiler does not do anything, my understanding is that the boiler is supposed to fire up when a hot tap is open. I have noticed that the preheat isn't working either the boiler is just sitting on Display 0.

No error codes are showing up.

Heres what i have tried so far;

I have replaced the diverter valve head, and PCB. No change.

I have removed the diverter valve and tested that the valve is moving in and out without getting stuck.

I have removed the heat exchange and flushed it out, to make sure there are no blockages.

I have tested the ohms on the thermistors, the central thermistor is reading 9.5 ohms
The return flow thermistor is reading 9.5ohms
The DHW thermistor is reading 12.4 ohms.

I'm not sure what else to test/ try now

Does anyone have any ideas as to what's going on?

 

[CBW]

Hope you tested for safe operation after slinging parts in. Did you check the resistors were operating correctly or just test the resistance value? What temperature did you test them at?

 

[DP]

I have tested the ohms on the thermistors, the central thermistor is reading 9.5 ohms
The return flow thermistor is reading 9.5ohms
The DHW thermistor is reading 12.4 ohms.

Are you sure?
9 and 12 ohms does not seem to be correct. That resistance would suggest very high heat- not even sure if the resistance would go down that low
Do you see a tap symbol indI sting hot water is demanded. If not, parts you have changed did not need changing

 

[mm915]

Are you sure?
9 and 12 ohms does not seem to be correct. That resistance would suggest very high heat- not even sure if the resistance would go down that low
Do you see a tap symbol indI sting hot water is demanded. If not, parts you have changed did not need changing

Sorry, when I say 9.5 I mean 9.500. See the image attached that comes from the manufacturers fault finding. The range 9,000 - 10,000 shows 25 degrees, which would mean they are fine.

 

[DP]

Are you sure?
9 and 12 ohms does not seem to be correct. That resistance would suggest very high heat- not even sure if the resistance would go down that low
Do you see a tap symbol indI sting hot water is demanded. If not, parts you have changed did not need changing

I know what typical resistances are for these thermistors. Also know that it cannot be 9-12 ohms which you wrote but meant x1000.

Perhaps your efforts would be better directed at thoughtfully following the sequence of operation. For instance, is the boiler recognising the hot water demand? Look at the display is a hint

 

[mm915]

I know what typical resistances are for these thermistors. Also know that it cannot be 9-12 ohms which you wrote but meant x1000.

Perhaps your efforts would be better directed at thoughtfully following the sequence of operation. For instance, is the boiler recognising the hot water demand? Look at the display is a hint

As stated the boiler dose not recognise any call for hot water, it sits at "0" Display.

 

[DP]

As stated the boiler dose not recognise any call for hot water, it sits at "0" Display.

Well that Is your fault then. Hint. What component tells the pcb hot water is needed just like programmer tellls the pcb heating is demanded.

 

[mm915]

Well that Is your fault then. Hint. What component tells the pcb hot water is needed just like programmer tellls the pcb heating is

I believe it was the thermostat or thermistor that was controlling the call for heat. Is that correct?

 

[Johntheo5]

Resistances seem OK, looks like it could be the flow switch??

 

[mm915]

Resistances seem OK, looks like it could be the flow switch??

Thank you I shall have a look at that when I finish work

 

[DP]

I believe it was the thermostat or thermistor that was controlling the call for heat. Is that correct?

Thermistor is boiler temperature sensor. That component will bring The temperature up to the mark the associated control on the front panel is set to.

Thermostat ( room) will tell the boiler the room is below setpoint on the room thermostat and to get working if so.

Similarly, running tap tells the boiler hot water is needed and associated thermistor takes the hot water temperature as set on the boiler front panel.