FU error code on Boiler

[Mr T]

Hello, we have a logic boiler and it keeps coming up with an FU error. It will start up and the temperature shoots up to 80plus and the error pops up for a minute then it drops back down to 60 and starts the process all over again.

 

Is there an easy fix for this that anyone is aware of or do i need to call out an engineer to have a look at it?

 

thanks for your help

[JohnMo]

Sounds like a flow issue, is your pump working?

[markc]

I love the FU error lol. Nothing like an appliance trying to tell you something.

short cycling so either nowhere to push the heat, boiler massively oversize or temps set too low for it to run properly

[PeterW]

FU on the ideal is a temperature error which is down to flow normally. Check no-one has closed a valve in error, and check the pump actually is working.

 

Dead pump, failed zone valve or blocked heat exchanger would all do this. Start with pump and valves - move them manually and check if it clears.

[Radian]

AIr lock? Mine does similar after a drain down for repairs. Got some awkward "local maximums" in the pipework leading to/from the boiler. Takes a few goes at bleeding everything before it runs normally.

[Mr T]

2 hours ago, JohnMo said:

Sounds like a flow issue, is your pump working?

Yes the pump looks ok

[Mr T]

2 hours ago, PeterW said:

FU on the ideal is a temperature error which is down to flow normally. Check no-one has closed a valve in error, and check the pump actually is working.

 

Dead pump, failed zone valve or blocked heat exchanger would all do this. Start with pump and valves - move them manually and check if it clears.

Will give it a go, thanks

[Pocster]

I get FU errors all the time …. 😁👍

[Mr T]

Checked the vales and pumps looks good, it should have an automatic air lock release so i am assuming its not that. Think i will need to get someone out. 😣

[Radian]

20 minutes ago, Mr T said:

it should have an automatic air lock release

It will only purge air in the pipes local to it, i.e. at a known high point. This is why I spoke of local maximums... pipe runs that have a discontinuous rise. Does your pump have an automatic purge mode? Most modern pumps have some setting that is optimised for getting rid of air locks by shunting them around and out through the automatic bleed valves. My system boiler nearly craps out within seconds of starting after a drain-down so I have the pump on a changeover switch which means I can run it in purge mode independently for 10 minutes or so. This usually does the trick but sometimes it takes a couple of goes.

[Mr T]

5 minutes ago, Radian said:

It will only purge air in the pipes local to it, i.e. at a known high point. This is why I spoke of local maximums... pipe runs that have a discontinuous rise. Does your pump have an automatic purge mode? Most modern pumps have some setting that is optimised for getting rid of air locks by shunting them around and out through the automatic bleed valves. My system boiler nearly craps out within seconds of starting after a drain-down so I have the pump on a changeover switch which means I can run it in purge mode independently for 10 minutes or so. This usually does the trick but sometimes it takes a couple of goes.

I am not sure if it has a purge mode. It could need a drain down which i will get someone in to do, i am not very competent with this stuff.

 

thanks for the advice

[Temp]

3 hours ago, Mr T said:

I am not sure if it has a purge mode. It could need a drain down which i will get someone in to do, i am not very competent with this stuff.

 

thanks for the advice

 

If you get the system drained and flushed out remember to put corrosion inhibitor back in afterwards. Some of these "Heating system plans" don't include that which is why I never sign up to them.