Remeha Avanta Plus 28c stuck at code 8

[john-doe222]

Hi,

Any ideas why would it stay at code 8 (not E8)? The pump is running continuosly.

I read this topic:

https://www.diynot.com/diy/threads/remeha-avanta-30v-code-8-pump-running-continuously.522890/

and this one:

https://www.diynot.com/diy/threads/remeha-28c-problem.390065/page-2

One of the last anwers was about leaking tap and I admit I had to change shower mixer cartridge, that was leaking. I thought that would solve the issue, but unfortunately not.

If the boiler is set to run in CH on and DHW on, it will get stuck on code 8 (pump will continue to run). It will heat the water, when the taps are open but CH will never kick in. When the taps are open, it will go over the normal cycle 1,2,4. When they are shut it will go back to code 8.

If I manually change boiler settings to run in CH mode only, it will supply CH normally. Once the stat temperature is met it will go to standby.

So for the time being (xmas and new year period) I have been manually switching between the two, changing settings on boiler panel. Now I am looking to actually nail the problem and find a solution, please.

Any ideas how to check if it is the diverter / some strange leak / actuator?
Any other ideas?

 

[CBW]

What zone valve do you have?

 

[muggles]

What zone valve do you have?

It's a combi

 

[CBW]

It's a combi

Agree, but have seen combi’s zoned off for heating and the OP has linked threads to zone valves.

 

[D_Hailsham]

Code 8 is a controlled stop. The Remeha manual says:

The Remeha Avanta Plus is fitted with an electronic temperature regulator with flow and return temperature sensors. The flow temperature can be set to between 20 and 85°C, see 2.9.8 (factory setting 75°C) The boiler modulates it's output up and down to match the flow set point from internal or external control. 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])

The pump is running in an attempt to lower the water temperature, but this does not appear to be happening. You can check the actual flow and return temperatures using the buttons on the front of the boiler.

Press the + key until t1 appears followed by a number. This is the flow temperature
Press the + key again until t2 appears followed by a number. This is the return temperature

If you continue to press the + key you will get:
t3 - should be --
t4 - should be -- unless you have a weather compensation sensor when it will show the outside temperature
F - ionisationn current -will be 0 if boiler is off
n - fan speed e.g. 30 = 3000. Should be 00 of boiler is off

Press + and it goes back to t1
Press R to clear the display

 

[snb]

Does the pressure gauge rise and fall when the pump activates? If it doesn’t it is most likely that the system needs more pressure as these often get blocked and give you a false reading

 

[john-doe222]

Code 8 is a controlled stop. The Remeha manual says:

The Remeha Avanta Plus is fitted with an electronic temperature regulator with flow and return temperature sensors. The flow temperature can be set to between 20 and 85°C, see 2.9.8 (factory setting 75°C) The boiler modulates it's output up and down to match the flow set point from internal or external control. 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])

The pump is running in an attempt to lower the water temperature, but this does not appear to be happening. You can check the actual flow and return temperatures using the buttons on the front of the boiler.

Press the + key until t1 appears followed by a number. This is the flow temperature
Press the + key again until t2 appears followed by a number. This is the return temperature

If you continue to press the + key you will get:
t3 - should be --
t4 - should be -- unless you have a weather compensation sensor when it will show the outside temperature
F - ionisationn current -will be 0 if boiler is off
n - fan speed e.g. 30 = 3000. Should be 00 of boiler is off

Press + and it goes back to t1
Press R to clear the display

Hi, thanks for replies.

When both CH and DHW are on and taps are open, boiler goes 1,2,4 and stays at 4 as long as the hot water is running. During this I get the following reading:
t1 - 50
t2 - between 42-45
t3 --
t4 --
FL - goes from 5.6 to 7.8 and stays at 7.7-7.8
nF - goes from 13 to 18 and stays at 18

When hot water is off, boiler goes back to code 8 and stays there forever... During this I get the following reading:
t1 - 49
t2 - 49
t3 --
t4 --
FL - 0
nF - 25

Does the pressure gauge rise and fall when the pump activates? If it doesn’t it is most likely that the system needs more pressure as these often get blocked and give you a false reading

I have noticed that the pressure is below 1 bar so wanted to top it up, but the gauge has not moved, so I stopped in a fear that I overdo it. The pressure gauge won't move at all regardless what state the boiler is in. So I anticipate that the gauge is either blocked or faulty as well?

 

[D_Hailsham]

When both CH and DHW are on and taps are open

You have a combi boiler, so CH and DHW cannot both be running at the same time. When there is a call for hot water (hot tap turned on) the diverter valve changes over so it stops heating the rads and heats the tap water instead.

The numbers look OK.

When hot water is off, boiler goes back to code 8 and stays there forever... During this I get the following reading:
t1 - 49
t2 - 49
t3 --
t4 --
nF - 25

Apart from the nF, which should be 0, all the other numbers are OK. The PCB is probably faulty. Baxi do a fixed price repair which you can pay by monthly instalments over a year.

 

[snb]

nothing wrong with the pcb. these ones are very robust. that fault is either the pump not pumping, low pressure, blocked filter on return near the air seperator or the diverter valve/ actuator

 

[snb]

when it is in code 8 you will have the fan running and the pump. it is doing that. points towards the diverter valve stuck in hot water position. take the actuator head and check that the pin moves up down. guess its stuck down in hw mode

 

[D_Hailsham]

when it is in code 8 you will have the fan running and the pump. it is doing thatof .

The fact that flow and return temperatures are the same proves that the pump was running. But why is it necessary for the fan to run, apart from a short time while it clears the exhaust gases from the hex?

 

[snb]

Just because the flow and return temps are same doesn’t mean the pump is pumping loads.
Fairly certain it is pumping continuous around the dhw plate with the actuator in the wrong position. But it could be pin stuck or actuator wet as these are prone to leaking.
On code 8 it thinks it has overheated and can’t shift the heat. As a precaution it is often pump failure or a circulation issue so to protect the main exchanger it keeps the fan running to cool it with air as well.
On the earlier models they didn’t have a low pressure sensor on system/combi and as the pcb is used on all models it just has that safety built in. If the main exchanger gets too hot it has fuse that blows and they wouldn’t provide a replacement. You can now get them as they are used on certain Baxi models

 

[D_Hailsham]

It might be worth checking the error history (the last 16 errors are held). The installation manual explains how to access and read the error data.

 

[john-doe222]

when it is in code 8 you will have the fan running and the pump. it is doing that. points towards the diverter valve stuck in hot water position. take the actuator head and check that the pin moves up down. guess its stuck down in hw mode

Thanks, but if the pin was to be stuck down in hw mode than why would the CH work fine when the boiler is set to be in CH mode only?

Regards,

 

[D_Hailsham]

why would the CH work fine when the boiler is set to be in CH mode only?

Which controls do you have, i.e timer/programmer and thermostat?