Vaillant EcoTec Pro 28 F.75 fault

[Homeglow]

Hi
I have been to a Vaillant Pro 28 and the symtoms are:

• Boiler modulating on low in both hot water/heating
• Coming up with F.75 fault
• Sounds like air in main heat ex when put into service mode and starts to bang as over heating

I have spoken to Vaillant tech three times now, i have cleaned the low water sensor and the problem is still there. I t sounds like there is air trapped in main heat ex, i have also put the boiler in purge mode three times. I was just seeing if anyone else as had these symptoms, I am going back to change the AAV, low water sensor and the two main flow/return pipes as they are the old type with the rubber connections on and I have been told these can cause blockages. I have also tried to bleed through the pump.

 

[JAP&H]

Hi Homeglow.

Possibly a restriction in water flow or pump issue rather than air in boiler/system.

 

[Homeglow]

Hi
I have changed a few pumps on the PRO but I can hear alot of water movement on this one, I have thought a blockage after a friend told me the problems associated with the rubber connections on the flow and return pipes. Do you think the blockage could be somewhere else?

 

[JAP&H]

When in heating mode can you feel the flow pipe getting hot?

Maybe keep boiler at minimum to avoid 'kettling'

 

[Homeglow]

The flow pipe is getting hot and the temp on display ramps up in seconds and then modulates right down to minimum, it only kettles when I put it in service mode. Just a pain in the bum fault, the tech guys said it could be one of 4 faults, its just a shame the parts cost money!

 

[sthmcrinstaller]

speak to your rep get the new solid pipes replace the water presure sensor check the aav is open . is the boiler in a loft ? put a system cleaner in the system

 

[sthmcrinstaller]

2ndry heat ex blocked or pump faulty or primary heat ex part blocked ......

 

[bobe]

i have had a simalar fault on a pro 28, if i reset the boiler it was rumbling and banging away the flame was modulating like crazy.turned out to be the reg on the gas meter have you checked inlet gas pressure.