Remeha Avanta 30V code 8 pump running continuously

[djmcc2001]

Hello,

Hoping someone can advise, our Remeha Avanta 30V heat only boiler has started showing code 8 on the display and the system pump runs continuously for hours when there is no heating demand. Normally with no demand it goes to 0 and everything shuts down. This has only started in the last few weeks. The boiler is piped to a pre-plumbed unvented cylinder where the pump is onboard, as far as I can tell this is working as it should as we have plenty of hot water and the two port valves operate to give heating to the rads etc.
It doesn't happen every day so it would seem to be intermittent.
The code doesn't have an 'E' prefix and doesn't appear in the manual. I have Googled the issue with a few people reporting similar problems but no suggestions to a repair.
The boiler was fitted Sept 2011 and has run perfectly up until now.
I am wondering if this is a PCB fault as the boiler otherwise works as it always has with no failure to give heating or heat the cylinder.
Appreciate any suggestions, thanks in advance.

 

[ianmcd]

is it definately the pump that is running and not the fan ? E8 is a fan fault

 

[djmcc2001]

Thanks yeah, definitely the pump. I have checked the 'FL' status when its doing it and its showing zero and the pump is running. The code is '8' rather than 'E8' so it's like a status code but not listed in the book. I believe faults have the E prefix. Would rather it was a fault code as it might make it easier to trace.

 

[ianmcd]

only thing I could think of is either a frost protection mode , or an over heat mode , both would have the pump over running , sorry cant be of more help

 

[ianmcd]

8 could be the temp setting for frost protection , think the default is 10 but not sure

 

[djmcc2001]

Thanks, will check that out in the manual and check the flow and return temps when it's happening to see if that gives a clue. System doesn't have an outside sensor so not sure if it would be frost related but will check those parameters. Cheers

 

[D_Hailsham]

It's not an error, hence no E; it's a "controlled stop"

When the boiler is at it’s at minimum output and the flow temperature still continues to rise, once the flow set point is exceeded by 5°C the boiler will shut down on a controlled stop - Code 8. See Installation Manual para 8.3.3

A Code 8 status will continue until the water temperature has reduced to below the set flow temperature. Monitor T1 (flow temp) compared to the set flow temp. If T1 drops significantly but the pump keeps running it suggests a fault in the PCB. See Manual para 4.3

 

[picasso]

A sticking endswitch on a zone valve will give the same symptoms.

 

[D_Hailsham]

A sticking endswitch on a zone valve will give the same symptoms.

But it won't give a Code 8.

 

[picasso]

So the valve closes but the endswitch is calling for heat , bypass wrongly set or missing where is the gonna go ?

 

[djmcc2001]

Thanks for the further replies. I hadn't thought the issue could be the zone valves. The pump has been running all day and I have just been up and checked the valves, both two port HP22 spring return valves with pre-wired plug in actuators (Range Tribune cylinder). Both set to Auto but I was aware that you could manually operate them. Gently pushed the rad valve from Auto towards manual and it sprung back as I believe it should. I tried the same with the DHW valve and it felt sticky and only seems to want to return back partially. While messing about with it the pump stopped... I then made sure the heating and hot water were fully off at the timeclock (no demand) and checked again. The DHW valve was at the same position as before, feels sticky and won't return properly, and when operating the lever the pump suddenly started, and then it stopped after a bit of fiddling.
I was thinking it could be a PCB fault but I think it seems sensible to replace the actuator or valve and see how it goes. I actually have a new spare actuator from when the heating zone valve was replaced a few years ago as the body was leaking so I may try the actuator first. Only problem is the spare doesn't have a plug in connector, so I either have to cut the old lead off and try and join the cables to retain the plug, or rewire back to the wiring centre assuming I can trace the cables. Anyway, possible progress and thanks for the replies. Will update if I resolve.

 

[snb]

But it won't give a Code 8.

a sticking end switch will give a code 8.

code 8 is due to flow temp being >5 than set point. end switch creates demand but no where for flow to go if auto bypass to close to boiler or not installed. it will eventually change to code 5 then code 3 then back to code 8 and continue the cycle

 

[djmcc2001]

a sticking end switch will give a code 8.

Thanks for your input that is exactly the cycling I am seeing on the display having monitored it earlier. The Range pre plumb cylinder does have a bypass and the cylinder is upstairs from the boiler, I wonder if the bypass is not set correctly as it appears adjustable? Certainly seems like the zone valve is causing the problem. Will investigate further tomorrow.

 

[djmcc2001]

Just to update, think I have fixed the problem. Fitted the new spare actuator I had left over from when one of the valve bodies was replaced a few years ago. I ditched the plug in cable so I just wired the new one straight into the wiring centre. Everything now seems to be working as normal again. Tested by adjusting the cylinder stat on and off, and the pump responded accordingly. No more Code 8..... ! Thanks for all the input, I would still be focused on the boiler if it wasn't for this forum.