Hi i was called out to a ravenheat csi 85t today and have fond a problem which stumped me. The boiler operates fine coming on and off ok but continually cycles. it will come on for 1 second at hi flame then drop to low for a second and cut out completley. this process complestes over about 3 seconds and hapeens continually when in ch mode dhw is not effected. bridged out the room stat and still happening. also the boiler is very loud on ignition, seems like over gassing, but burner pressure and rating ok. when the modulator for the gas valve is disconnected when lit all is well. could this be a fault with the gas walve or pcb ?
Ravenheat Problem
- Thread starter danderson01
- Start date
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CH thermistor is most likely. There are other possibilities but they are not even worth mentioning in this case until you have eliminated that one.
also another thing i forgot to mention, when the modulting coil is disconnected from the pcb the boiler works fine abeit at 2mb insted of 4mb. which leads me to think it could be the modulating coil, however did not have my multimeter with me at the time to check.
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2mb is right for min pressure [10.5mb max]
Did you ever resolve this one? My Ravenheat CSI 85 has just developed exactly the same problem.
Agile,
Thanks for responding. Since I found this thread I can across your dicussions with psarinuk in November. Yes, it sounds like the fan control PCB. I'll give it a try.
I'd still be interested to know why running the hot water for 30 seconds, as psarinuk described, gets the boiler back to working normally.
Malcolm
Thanks for responding. Since I found this thread I can across your dicussions with psarinuk in November. Yes, it sounds like the fan control PCB. I'll give it a try.
I'd still be interested to know why running the hot water for 30 seconds, as psarinuk described, gets the boiler back to working normally.
Malcolm
I was really hoping for a reply from another gas engineer so that he and I could give you some guidance.
The problem is that few homeowners ever have the courtesy to report back what the problem was so we often dont know if our suggestions were correct in the circumstances.
Many boiler faults seem very similar to users! Cold rads or cold "hot" water in most cases!
Tony
The problem is that few homeowners ever have the courtesy to report back what the problem was so we often dont know if our suggestions were correct in the circumstances.
Many boiler faults seem very similar to users! Cold rads or cold "hot" water in most cases!
Tony
Its a CSI 85 T and has 2 lights on the front.
Another piece of information, this cyling happens from cold start only and, if left, continues for about 20 minutes (although I have not timed it acurately) after which the boiler operates as normal.
Another piece of information, this cyling happens from cold start only and, if left, continues for about 20 minutes (although I have not timed it acurately) after which the boiler operates as normal.
Well I don't have that much to go on but from what I can figure out is that your boiler is post Sep 2005 and probably pre March 2006.
I'd be looking at the function of the fan first. Does it sound like its struggling to start up? My bet is that its stiffening up causing the APS to drop out and eases off as the boiler warms up.
Remember it could be one of many things and that I am just letting you know what I think is most likely cause.
I suspect that your boiler may not have a fan modulation pcb
I'd be looking at the function of the fan first. Does it sound like its struggling to start up? My bet is that its stiffening up causing the APS to drop out and eases off as the boiler warms up.
Remember it could be one of many things and that I am just letting you know what I think is most likely cause.
I suspect that your boiler may not have a fan modulation pcb
Your estimate of the age is about correct. The fan does not sound as if its struggling but would there be a problem with the fan if the boiler operates normally under hot water demand?
I previously advised that turning on the hot water stops the cycling and brings the boiler back into normal operation. However I established this morning that turning on the hot water does not stop the cycling when the boiler is completely cold. It would appear that the boiler needs to warm up a bit, as a result of the continual cycling, to respond to this.
Is the the last sentance of your message incomplete?
I previously advised that turning on the hot water stops the cycling and brings the boiler back into normal operation. However I established this morning that turning on the hot water does not stop the cycling when the boiler is completely cold. It would appear that the boiler needs to warm up a bit, as a result of the continual cycling, to respond to this.
Is the the last sentance of your message incomplete?
Its complete apart from the full stop!
What Slug is suggesting is that the fan bearing may be stiff and failing to run fast enough at low power.
That may be the case or if there is a fan mod PCB then they fail to run the fan properly are low speeds.
Does the fan turn totally freely by your fingers when its cold?
Tony
What Slug is suggesting is that the fan bearing may be stiff and failing to run fast enough at low power.
That may be the case or if there is a fan mod PCB then they fail to run the fan properly are low speeds.
Does the fan turn totally freely by your fingers when its cold?
Tony
Thank you, I understand.
I thought that the word 'problem' may have been missing from the end of the sentence. I confirm that the boiler does have a fan mod PCB.
The fan does run freely when spun by hand and there appears to be no bearing stiffness.
I thought that the word 'problem' may have been missing from the end of the sentence. I confirm that the boiler does have a fan mod PCB.
The fan does run freely when spun by hand and there appears to be no bearing stiffness.
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