Code F5

Discussion in 'Plumbers' Talk' started by gswainyboy, Jun 9, 2019.

  1. gswainyboy

    gswainyboy Member

    Hi.We live in a bungalow with a micro bore c/h system (Which I know is a bad start !!!) and 100HE british gas boiler.F5 fault came up which appears to be overheat problem.I removed front cover,internal cover and reset red button,reassembled and boiler fired up and c/h and hot water all ok although knocking when running.I then decided to flush system so connected pipe to drain off,isolated water into header and undid drain.I assumed that all water would drain from sytem including header and i could run clean water through,then bleed all rads and re-fernox.I also removed ,cleaned and refitted Magfilter which only had small deposit of sludge.The water wouldnt drain from the system,only a small amount having released bleed valves to avoid suction.Ran out of time so turned on supply again but now nothing is coming out of bleed valves when I loosen.All ideas gratefully received thanks.Graham
     
  2. gswainyboy

    gswainyboy Member

    Sorry,should be British Gas 330 boiler although I think its the same animal.Cheers again,Graham
     
  3. Mike83

    Mike83 Well-Known Member

    It sounds like the cold feed from the header tank is blocked.
    Can you trace this pipe from the tank to where it tees into the pipework?
     
  4. gswainyboy

    gswainyboy Member

    Hi Mike. Many thanks for your reply. Unfortunately we have a christening today so won't be back on it until tomorrow (lm retired) but will make that first thing to check. Again, thank you and will let you know tomorrow. Have a good day. Graham
     
  5. CGN

    CGN Well-Known Member

    Can be a pita to refill. I once had to resort to reverse filling by connecting a hosepipe off the mains to a downstairs radiator drain valve to refill.
     
  6. gswainyboy

    gswainyboy Member

    Will also take that on board thanks CGN. Will see what happens tomorrow and keep posted on here. Thanks for that. Graham
     
  7. gswainyboy

    gswainyboy Member

    Hi Mike.Before i start presumably I am right in thinking if I open the lowest drain cock and isolate incoming supply the complete system should drain,including header tank.ie There are no valves etc in the boiler,pump,mag. filter etc that would hold the water back.Just thought I would check before I start.Thanks,Graham
     
  8. Mike83

    Mike83 Well-Known Member

    The only thing that would need manually opened to help the system drain is the zone valves.
    If the header tank doesn’t drain it could indicate a blocked cold feed between the tank and where it tees in.
     
  9. ajohn

    ajohn Well-Known Member

    The pump may be worn out as well. ;) Don't ask me how I know. Ours doesn't have an F5 fault but ....................................

    You may have a partial microbore say 10mm. The main circuit pipes could be larger.

    John
    -
     
  10. gswainyboy

    gswainyboy Member

    Hi all.You were as good as right Mike.I located a gate valev further down under the insulation and this was totally seized and gunged up. Fitted new then took out header tank and cleaned out,new ballcock and then flushed out.Am I right in thinking that each rad has to be drained down and flushed as they are all fed seperately from 2 manifolds (Pictured).Did all this,bled throughout but now five rads are working,hot water all ok but getting knocking/banging from boiler and nothing at 3 rads.Boiler keeps cutting in and out all the time.Once again,any ideas would be greatly appreciated,
    Thanks,Graham
     

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  11. Mike83

    Mike83 Well-Known Member

    Get the system drained as much as possible.
    Fit a magnetic filter (adey salesman will be along soon).
    Get some chemical cleaner running through the system.
     
  12. gswainyboy

    gswainyboy Member

    Hi Mike.It has a Magnaclean Professional fitted already which I have already taken out and cleaned but I will get along and get that cleaning additive in the system and give it a good run.Presumably Im still looking at sludge am I.There was about 2" layer in the bottom of the header tank before I removed it and cleaned,hosed out.Will keep you posted and thanks for your advice once again.
     
  13. gswainyboy

    gswainyboy Member

    Just thought as well.As I said,the system has 2 manifolds,splitting the 8 rads in half. the 4 situated off 1 and nearest the boiler are all fully up to temperature,the next 2 off the other manifold but further away from boiler are working but not as hot as they should be and the 2 furthest from the boiler off same manifold are cold.It almost seem that the pump doesnt have enough umph to reach the last 2.Just thought Id throw that in as well.
     
  14. Mike83

    Mike83 Well-Known Member

    Could be the pump.
    Try turning off all the rads that work fine.
     
  15. gswainyboy

    gswainyboy Member

    Sorry to test your patience again Mike but this morning the hot water is up to temperature and all ok. On the C/H side I turned up stat and set timer so that it would run constantly just to see what happened and the boiler is starting and stopping on these settings so the rads are not getting chance to heat up. Not sure if its related but should the lever on the side of the 3 way valve actuator always have resistance only it just flops up and down and does nothing.
     
  16. KIAB

    KIAB Well-Known Member

    Add some cleaner to system like Sentinel X400 leave it for a week or ideally longer to work, can stay in up to 3-4 weeks, then drain & throughly flush system after using X400.
    Will need to check filter several times a day.

    As you got a Magnaclean Pro fitted, you could buy a secondhand Magnacleanse from Ebay & connect that to system, leave it on for a few weeks to work,after you finish with it, put it back on EBay ,should get your money back.
     
    Last edited: Jun 11, 2019
  17. Mike83

    Mike83 Well-Known Member

    Usually have a little resistance.
    Depends on the valve though.
    Some manufacturers levers differ and they can sometimes snap without the valve actually going faulty.
     
  18. gswainyboy

    gswainyboy Member

    Just totally baffled now as boiler came back on ,kept running and 6 out 0f 8 rads are up to full temperature again then it just cut out .
     
  19. gswainyboy

    gswainyboy Member

    Me again.Thanks again all,especially Mike for all your input,advice etc.We now have hot water on tap and heating fully on all rads.I am still going round and bleeding rads as the boiler does still cut in and out when it should be continuous. Im happy that the system is clean now as ive had hose up in loft and opened drains on both ends of bungalow (seperately) and flushed through.Am now inclined to assume a component in the boiler is the culprit but presumably this will be out of my scope.Would just appreciate any thoughts on what component its most likely to be that will cause this.Again,thanks for your invaluable help,Graham
     
  20. The Teach

    The Teach Well-Known Member

    Is there any fault code displayed ? what is the displayed temperature when it goes off ? IIRC that boiler is 18kw output (factory setting) although the installer can range rate it between 12-30 kw. the actual Kw output is confirmed on the data badge by an arrow pointing towards what the installer has set up to.

    The boiler will cycle on-off-on off,some system balancing under all operating conditions to ensure the 20°C flow/return differential is correct can reduce the cycle rate.

    TT
     

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