Ravenheat CSI 85 Pump running intermittently day and night

21 Feb 2007
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United Kingdom
I have a problem with a Ravenheat CSI 85 (26 months old) which intermittently runs the pump even when i have not requested DHW / CH.

It can come on anytime during the day or night stays on from between two and twenty minutes then switches off. The boiler does not try to light and other than this the boiler is working fine.

If I turn the boiler off at the mains then back on this can sometimes stop the pump running and also if I run the hot water for a few minutes to heat the water up then it can stop it, I am not sure if this is relevant but it's not another thermistor problem is it?

Any ideas? - when it comes on at night i wake up and it's driving me mad!
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Frost protection and/or pump excercise.
Hi UF6,

Thanks for your reply.

This has only started happening recently so frost protection could make sense - is this normal or could it be a problem with the frost temp sensor making it kick in when it's only cold instead of proper winter cold?

What sort of temp does frost protection normally kick in at?
My CSI85AT did exactly the same thing. It eventually started lighting and going out etc and then stopped lighting all together. The problem was the C.H. thermistor intermittently going open circuit. Eventually it stayed open circuit.

This will cause the pump to run even if there is no call for heat.
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You've got a Ravenheat CSI85 and its running intermittently?

You're lucky!!!
Hi Woolf - tell me about it!!

Thanks SueBeebies - I have just replaced the old style (inside the pipe) DHW & CH Thermistors with the new style clip on ones - and all is well!!
(hopefully these ones will last a bit longer as I have already replaced the others a couple of times!)

Thanks for the advice!

(My boiler did start lighting on it's own as well!)
Sorry Louis, it was the cold. It brought out the irony in me.

Anyway, I'm glad that you seem to have solved your problem - best of luck and fingers crossed.

I maligned my CSI85 - it's now intermittent again. It's 9.20pm and it's just come back on. Perhaps there is a boiler god after all. My engineer visiteth on Thursday…

Ahh there's your problem Woolf, if you throw such language at your boiler then of course it's going to break down - you have to be nice to it - remember while all the other boilers were being bought at full price the only way this one got sold was on special offer!

(Hope everything gets sorted on Thursday!)

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