Ideal Logic Heat 18 a mind of its own :)

11 Sep 2016
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United Kingdom
i recently moved into my new flat
I have an Ideal Logic heat 18
A drayton thermostat RTS8 (just been replaced)
a drayton LP722 programmer
Hot water tank also have a thermostat which i set to 45.

Boiler seem to fire up at random times and does not follow thermostat or programmer.
Programmer is set to Off, Thermostat to 10c
Testing various combinations but doesnt seem to follow thermostat or programmer at all.
The boiler is set to E (Zero, E, Max) and the right hand side leaver is set to On.. (i also tried reset position).

When the radiator thermostats are triggered.. CH goes on it seems its the only way to turn rads on.. (Programmer and thermostat remain off)

can someone help or shall i get the experts in?

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i can see two danfoss valves both set to MAN position (NOT AUTO)
Last edited:
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hertsboilers: your questions prompted me to research more and experiment more..
it seems that after switching both valves to Auto the boiler now reads 0 on display (instead of C which always on), Zero which means on standby...
i then programmed the programmer and tested and it works... so basically because the original thermostat had broken and they couldnt operate CH they put valves on manual.. and left it for me to deal with. Nice!

Thank you for your response.. your question led me to work out the solution.. much appreciate it

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