Reverse flow conundrum

[Greenyboy]

Hello all,

An issue some advice would be great on if you can.

Boiler with no leaks, holding pressure fine with a reverse flow FA fault code. If you drain the system and refill, obviously bleeding pump and rads, the whole things runs smoothly for about 5 to 7 days. At a random point it will then dump about a bar of pressure and FA code comes up. Topping up won't get it started again and all that will work is a drain down and refill. Changed dump valve and expansion vessel and pump works fine. Any ideas?

 

[Deleted member 120897]

Ok, firstly what boiler and system are we talking about? S plan, y plan, w plan, c plan, Combi boiler, heat only boiler system boiler?

 

[Greenyboy]

It's an ideal logic 18 if that helps

 

[Deleted member 120897]

Can you post photos of your motorised valve(s), pump and cylinder cupboard? Including any arrow indicators.

 

[Greenyboy]

Here you go. Thank you for helping by the way. Really appreciate it.

 

[Deleted member 120897]

Are the directional arrows the correct way on the Honeywell valve and the pump?

 

[Greenyboy]

Yes the arrows are all good. Been installed and running for 5 years so don't think it's a matter of being installed wrong way around

 

[Chuck]

Yes the arrows are all good. Been installed and running for 5 years so don't think it's a matter of being installed wrong way around

If it isn't the pump and this is a new problem then it's probably the PCB. Needs a registered gas engineer to make the repair. Check your warranty and/or a fixed price repair because, if I'm right, it's an expensive part. Ideally you'd leave a datalogger attached to the flow and return outlets to see what happns when the fault it triggered just to check that it's the boiler at fault and not some strange plumbing/valve issue.

If you are Gas Safe and want to discuss the details details, you'll need to provide the forum moderators with your Gas Safe registration details.

 

[John.g]

Maybe something as simple as a sensor problem?. If pressure is holding steady for 7 days then check PRV for leakage, watch boiler pressure cold/hot and see it doesn't exceed 2.5bar or so (lifts at 3.0bar)