No heating, but hot water (diverter?)

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Hampshire
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Greetings,

I have an awesome Isar Ideal HE24, it came with the house; to be fair, it's caused no problems hitherto. I removed a radiator while decorating, and wanted to test the system/check for leaks when it went back together. No heating, but hot water - looking online it seems most likely to be a diverter valve, as the heating hasn't been used in a fair few months. I can't really touch a boiler, so I'll call a heating engineer out; I just wanted to see if there was anything I could check.

I've a Drayton wireless digistat, which has new batteries. There's no error on the stat, and it correctly shows the flame icon when I increase the desired temperature; the boiler does nothing, and presents no messages on the LCD.

Is there anything obvious, or a way of over-riding the stat?
 
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But does the receiver unit show a demand for heat? Usually a green light?

It sounds as if you may need to re-establish the communication between the two units.

Look up the instructions on line and try to follow them exactly.

Tony
 
Hi Agile,

Thanks for the advice; I don't recall there ever being a green light on the receiver, but it's not showing an error. I'll dig out the manual and re-pair them.
 
If the display is showing 0 then the boiler isn't getting a demand to run the heating. Its most likely to be the receiver box for the room stat not switching.

In CH demand the display should read C. irrespective of the diverter position the boiler would still try and run CH if there was a demand.
 
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Hi again,

I paired the receiver and digistat, and it appears to function as it should - the green light comes on when the stat is turned up. The heating however does not turn on, there is no message or icon on three boiler screen. It seems unlikely that the wires between the receiver and boiler are suddenly a problem, no?
 
At least a green light!

The receiver could still be faulty.

next it needs a test meter to see of the RX box contacts are closing.

Tony
 
Hi again,

By that, do you mean to check the output of the receiver with a multimeter? I guess I could turn off the power, and put some wire between the two thermostat connectors?
 
Its always better to test with a meter if you have one and know how to use it.

You could get an idea though by identifying the call for heat terminals from the RX unit and joining them together!

But that needs competency with following the circuit.

Tony
 
I couldn't be without my multimeter!

I'll give it a go, and call a heating engineer if the signals look good. Not much I can safely check myself beyond that.

Thanks again!
 
Thanks for your help, i got it nailed.

Removing the thermostat and bypassing it with a wire, it fired up as normal. Turns out to be a common way for the digistat scr to fail - new capacitor (£4) sorted it out .
 

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