Old Myson Apollo pilot light keeps going out!

Discussion in 'Plumbers' Talk' started by aak, Apr 1, 2021.

  1. aak

    aak Member

    Dear all, just looking for a sanity check:

    have a very old boiler which is probably on its last legs, not sure of exact model but its a Myson Apollo. Only replacement I will be allowed is an electric one because of recent regs, so trying to keep it going for as long as possible.

    The pilot goes out and restarts, but tends to go out again a day or two later. This has been happening for a few years, and usually lasts a couple of weeks, usually in the dead of winter and heart of summer, and then the boiler reverts to acting normally.

    The last time I had someone look at it a number of years ago, the thermocouple was fine, all other checks were fine, and a sharp knock to the side of the boiler resolved the issue, the boiler engineer telling me that sometimes some debris just needs dislodging.

    I'm being told this time, just from relaying symptoms over the phone, that its a main circuit board that is likely the problem and should be replaced - does that make sense?
     
  2. Mike83

    Mike83 Screwfix Select

    You need the exact model.
    If the boiler has a thermocouple then it’s normally not got a pcb controlling the ignition.
    On some models the pilot going out can be the boiler overheating.
     
  3. Dave does Gas

    Dave does Gas Screwfix Select

    There is an overheat stat on those linked to the thermocouple, you can test its at fault by linking it out. It may also be a dirty pilot injector which you possibly cleared by the good old thump it method
    However one major issue with those old boilers is the asbestos they used to use for the seals. I would advise not opening it up ever again if you value your long term health.
     
  4. aak

    aak Member

    thank you both. ive tried to find the exact model but am struggling to find it - is there an accessible plate ive been blind to? am certainly not going to attempt to open anything up on my own as a mediocre diy-er. just wondering whether the engineer I spoke to is trying to pull a fast one.
     
  5. aak

    aak Member

    its def
    its definitely got a thermocouple, I remember it being replaced a couple of times in the past.
     
  6. Call another engineer. At the same time he could be saying that to avoid job/liability. A engineer who has helped me on some big installs in the past avoids all old problematic boilers as if you work on it you also take on the responsibility of its safe working condition (which he is not willing to do).

    On another note, what regs make a new boiler impossible?
     
    aak likes this.
  7. aak

    aak Member

    It could be, yes. It’s in a block of flats and I’m told a new gas boiler install will require flue access that is not possible, so other residents have been opting for electric.
     
  8. teabreak

    teabreak Screwfix Select

    Worth getting a gas engineer to fit a new pilot jet assembly they are very odd if it's the one I am thinking of.
    It has a spring , two flames one out of the end one to light the burner and a side one to heat the thermocouple, the end one can "rob" the side jet causing the thermocouple to cool. If that is the one he needs to fit the brass head, the spring that goes around it and most important the injector jet which has a minute almost square shaped hole in it, often cleared out round with a pin by fitters which does not then work properly. As said it has an overheat trip that will cut the boiler off if faulty or overheating.
     
    aak likes this.
  9. aak

    aak Member

    thanks for that tea break. when it is on and heating, it does keep switching on and off which im assuming is the overheat trip doing what its supposed to do.
     
  10. teabreak

    teabreak Screwfix Select

    The switching on and off is the thermostat, the OH trip is a second line of defence if the boiler overheats for any reason, faulty thermostat, lack of water, poor circulation, excessive scale in the heat exchanger etc.
    Does it have a high low switch on the control panel?
     
  11. aak

    aak Member

    ahh, I see. yes it does: high, low and an intermediate 0 position. its switching on and off every 20 or 30 seconds and the rads are all very hot, although room temperature is not quite at the room thermostat set temperature yet.
     
  12. teabreak

    teabreak Screwfix Select

    It has a very basic thermostat just two settings if it goes off on the thermostat it comes back on as yours does, but if the overheat trips the thermocouple cuts the gas off just like a faulty pilot would and you have to relight the pilot. They were prone to overheating, worth trying to run it on the low setting to see if it tolerates that better. Your rads will be cooler but if that improves things chances are the boiler is scaled up they were very prone to overheating even when new. If the problem persists despite running it low get your fitter to try a new pilot assembly. That boiler has done very well to last this long.

    Unless you are on the first floor as you say access is difficult, have you had anyone look at the job to see if they can get a boiler in somewhere?
     
  13. aak

    aak Member

    great thanks for that message, its very clear. its set on high, so ill drop it to low and see if that does make a difference. incidentally, what does the '0' option do? I am on the first floor! building management have made it clear that there are unfortunately no options. its a listed building so access can only be to the roof and I think they standardised that for all the apartments in the building.
     
  14. teabreak

    teabreak Screwfix Select

    0 will simply be off as far as I know.
     
    aak likes this.
  15. teabreak

    teabreak Screwfix Select

    From what you say it sounds like an old open flue installation where a large flue piple goes up to the roof and air is drawn from the room via a dedicated air vent in the wall or window, rather than a balanced or room sealed type that goes straight out the wall discharging the fumes and drawing in air directly to the burner from outside.
    If it is any consoulation that is the least efficient system of boiler, so a switch to electric may well be a good option.
    Please do let me know how you get on with it though.:)
     
    aak likes this.
  16. aak

    aak Member

    thanks very much tea break, I will do! am awaiting to hear back from my plumber, and will watch to see if the pilot is less inclined to self extinguish now.
     
    teabreak likes this.
  17. Dave does Gas

    Dave does Gas Screwfix Select

    Sounds like your boiler is part of a U or SE duct which were built to accomodate multiple appliances and are not suitable for modern HE boilers which will be why everyone has gone across to electric. Your boiler is not open flue as Teabreak hinted at otherwise it would be in a shunt duct. Like I said before If it was me attending the breakdown I would refuse to open it as Its on the asbestos list. Your best bet would be to bite the bullet and convert to electric.
     
    aak likes this.
  18. teabreak

    teabreak Screwfix Select

    Did cross my mind Dave but never seen one on a se duct masses of halycon F60's though;)
     
  19. Dave does Gas

    Dave does Gas Screwfix Select

    We only have one building here in Southampton which has a SE duct. Its now redundant, but every ACS whats the main questions on in the Flueing section.
     

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