Boiler overheating...

Discussion in 'Plumbers' Talk' started by fooey, Sep 28, 2020.

  1. fooey

    fooey New Member

    Hi all,

    Firstly I should state that there's a small leak in one of copper pipes leading to my glowworm complheat 55 boiler - it means that pressure drops every once in a while and I have to re-pressurise every fortnight or so.

    My townhouse spans 4 floors and I have added 4 radiators (now 17) in the last year or so - loft conversion/ first floor converted to open plan. Of the 4 new ones, two are pretty large and from memory I think are around 8000 BTU each. My boiler has since started to overheat - to get it working again, there's a button underneath the boiler I have to press to reset it. I think the issue must be related to the fitment of the additional radiators? Perhaps the boiler doesn't have the capacity to service all the radiators, remains on all the time and thus overheats? Just my guess...

    Can anyone tell me how I can address this problem? Do I need to install a new boiler or will fitting an upgraded pump in the boiler do any good?
     
    RobJamesHeating likes this.
  2. sam spade

    sam spade Active Member

    Don't recognise that model. What is the GC Number?

    Edit

    Found it; it's a Fuelsaver Complheat 55.
     
  3. sam spade

    sam spade Active Member

    I think you are right. 17 radiators will be anything up to about 25kW (BTU is like pounds, shillings and pence - it's obsolete), while your boiler can only produce 16kW - and that was when new. Its now between 18 and 29 years old so the output will have inevitably dropped.

    I think it's time to think seriously about a new boiler, but don't take the exsting radiators as a guide as they may be oversized (good) or undersized for the heatloss from your house. A responsible heating engineer should carry out a heatloss calculation and base his recommendation on that.
     
  4. If your boiler is overheating then there's not enough water flowing through it so you either have an air lock or a blockage.
     
    The Teach likes this.
  5. The Teach

    The Teach Screwfix Select

    Ok that needs immediate retification,winter is on its way ;)

    ask the person who extended your system and request they can confirm the existing expansion vessel has been serviced and is suitably sized for additional load.

    there an Ok gas boiler but need consideration to correct installation and servicing, just makes them last longer ;)

    Others will have differing replys ,hey thats whu you came to a diy forum.

    Xmas:)
     
  6. fooey

    fooey New Member

    Thank you for all your replies
     
  7. Dave does Gas

    Dave does Gas Screwfix Select

    Its ancient ;)
     
  8. fooey

    fooey New Member

    I just spoke with a plumber and described the problems I am having. He said a new boiler might help but that I should try getting it powerflushed first (something I would have to do anyway when installing a new boiler).

    I found a company that powerflushes on google, they said that I should fix the leak before powerflushing as the system will probably get dirty again if the system is losing pressure. I was wrong, I actually have 13 radiators and not 17, he quoted a price around £500. When I told him that the piping in the property is 8mm, he said that the system is not suitable for powerflushing and that doing so could cause permanent damage to the pipework. He recommended powerflushing.

    I've just gone online and found that to powderflush 13 radiators is around £1000!!! This is going to be expensive!

    Does the advice given to me sound about right?
     
  9. Dave does Gas

    Dave does Gas Screwfix Select

    Yes Microbore (8mm and 10mm) cannot take the flow rate to make a powerflush work properly and will probably clog up somewhere.
    Cheapest option is to fix the leak first then add a good cleanser like X 800 for a day or so then flush it out and test the system. May work, may partially work but it will improve what you have at present
     
  10. fooey

    fooey New Member

    Thank you so much for your help, I have added X800 to the system and will drain it tomorrow. Hopefully this makes a noticeable improvement.
     
  11. Dave does Gas

    Dave does Gas Screwfix Select

    Run the system as much as you can stand it, the more heat the better
     
  12. sam spade

    sam spade Active Member

    X800 can be left in for longer than 24 hours. I would leave it for a week then drain and flush the system several times with fressh cold water. flush each rad in turnby turning all off except the one you are flushing. (Make a note of the lockshiled valve settings first so you can reset them correctly.)

    Don't forget to add inhibitor X100 at the final fill and reset the LS valves to their original settings.
     

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