i have heard of this and what happens is software on the pcb notices when temps rise or fall too fast and it blocks out the burner and hovers between 45degrees to 53 or 54. Usually happens in large properties where there is large cylinders/underfloor heating. I've been told that they can fit a new pcb which hasn't got this software on. Is this what is happening to yours?? If they changed heat ex then i imagine it is not and it is overheating!(which could well be your system/setup!)
If its in warranty still maybe see if worcester will send out a senior tech engineer to have a look! Their diagnostics are very good at watching temp rises etc!
hope this helps!
POSSIBLE SOLUTION **** POSSIBLE SOLUTION **** POSSIBLE SOLUTION ****
for anyone who is searching for the SOLUTION to this issue (and I know from posts on many forums that this is an issue that effects a number of people), I just wanted to state here what one possible SOLUTION is
I had a great Worcester Bosch engineer out this weekend who quickly diagnosed the issues and resolved it by replacing the circuit board. boiler now working as new, no issues whatsoever, lovely hot water and heating!
My advice: if you have this problem, or any similarly frustrating problem, give Worcester a call directly.
there is no way I could have ever solved this issue and advice I'd had ranged from re-plumbing the entire system, powerflush, changing the pump, changing the zone valves, changing the heat exchanger, changing the HWC - the list goes on and none of them were correct. (which to be fair, isn't that surprising as at least some of those people hadn't ever looked at the system, so unfair to expect a correct diagnostic - I'm merely saying that perhaps you don't just jump to a quick, say, pump change and hope it fixes the issue)
NOTE: I do not work for or have any relationship with anyone who works for Worcester Bosch whatsoever
I know this thread has been running for a few years but I felt it was worth sharing my own experiences:
I have a Worcester Bosch 40 CDI Regular boiler which was installed 8 years ago in 2010. I had this same problem recently with the boiler service manual indicating "
The gradient limitation is active. The primary temperature is rising too fast and the burner has switched off for 2 minutes. See error E9."
I spent some considerable time and effort checking out the water flow, replaced the pump and had the boiler serviced by a certified Worcester Bosch engineer. On my own initiative I then approached Worcester Bosch for a solution and they suggested replacement of the boiler PCB. I was able to source this at a reasonable cost (<£50)and the replacement was fitted in 15 - 20 minutes. Problem solved.
It was only after this that I found this thread which I wished I has found earlier. What makes me particularly angry is that Worcester Bosch, it's agents and an experienced plumber were not able to solve this themselves. The service booklet for engineers has errors in the E9 rectification process. It is possible that I had the problem to some degree from when the boiler was installed. The solution was I believe an upgrade in the PCB firmware and should have been made available by Worcester Bosch as a fix under warranty or at least circulated to their agents as a known problem and an exchange process put in place to obtain an updated PCB.
Well done boilerdoctor almost 100% correct except the PCB was brand new. I also failed to say that the problem was intermittent and 9 times out of 10 the boiler fired up to full temperature correctly.
However my point is that if I had found theSouth's post sooner I would have found the solution a lot sooner. This solution should have been forthcoming from Worcester Bosch and/or its agents. I should not have to resort to the web to find a solution and advise my plumber/boiler engineer how to fix the problem.
My advice is the same as theSouth's "if you have this problem, or any similarly frustrating problem, give Worcester a call directly and refer to this stream." It takes no time at all to check the pcb software version.
Hi. I am having the same problem and wondered if you had any details on the PCB that was replaced? I would like to order one to try but not sure how to get one. Many Thanks.I know this thread has been running for a few years but I felt it was worth sharing my own experiences:
I have a Worcester Bosch 40 CDI Regular boiler which was installed 8 years ago in 2010. I had this same problem recently with the boiler service manual indicating "
The gradient limitation is active. The primary temperature is rising too fast and the burner has switched off for 2 minutes. See error E9."
I spent some considerable time and effort checking out the water flow, replaced the pump and had the boiler serviced by a certified Worcester Bosch engineer. On my own initiative I then approached Worcester Bosch for a solution and they suggested replacement of the boiler PCB. I was able to source this at a reasonable cost (<£50)and the replacement was fitted in 15 - 20 minutes. Problem solved.
It was only after this that I found this thread which I wished I has found earlier. What makes me particularly angry is that Worcester Bosch, it's agents and an experienced plumber were not able to solve this themselves. The service booklet for engineers has errors in the E9 rectification process. It is possible that I had the problem to some degree from when the boiler was installed. The solution was I believe an upgrade in the PCB firmware and should have been made available by Worcester Bosch as a fix under warranty or at least circulated to their agents as a known problem and an exchange process put in place to obtain an updated PCB.
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