worcester 28i junior dhw does not switch on on demand

[ineke]

For the last 3 weeks, when I open a hot water tap, half of the times the boiler does not switch on. Initially after opening the tap there is some clicking and humming sounds (as if it wants to start up), but then the warning light flashes fast (about 4 times a second). If I leave the tap running, switch off the main electric switch, then switch it back on, usually the boiler kicks in and gives me hot water without a problem. Occasionally I need to switch the electric main switch twice or three times. On some days it doesn't have this problem at all (which is frustating as I already had 1 visit of a Corgi registered plumber on such a day and he couldn't find any fault). Quite often the problem is at it's worst late at night (I am not on mains water, but spring water which is fed into the house under pressure by pump). The CH seems to be fine when I tested it (still not on during the summer (?) months). Additonally I have noticed that the times that the boiler does come on on demand of hot water, it takes quite a bit of time before the boiler finally starts burning.
Does anyone have any idea what might be the problem. The plumber did check the fan and airtubes and found them unobstructed.

 

[Agile]

If you dont have mains water then I would guess that the boiler is on LPG ? That may well be very relevant!

Do you have a cooker operating from the SAME LPG supply?

Could you turn on three burners and see if the boiler still behaves the same way?

Regardless, I suspect its a combustion setting related problem although I dont yet know what.

Is Carrodon Gas Services close by? Let Barry have a go if he is qualified to work on LPG.

Tony

 

[ChrisR]

WHat hot water flow rate do you get? It should be about 10 litres per minute.
If it's too low the boiler won't go.

 

[ineke]

Hi, thanks for the quick replies.

I'm lucky and have mains gas. Nevertheless I did the suggested test, turned on 3 burners of the cooker (on the same gas) and turned on the hot water. It came on without problems. Admittedly, so far today the boiler hasn't shown any problems, which is good but also infuriating.

I also tested the hot water flow rate: in the kitchen it was 9l/min; and in the bathroom (shower) it was 7 l/min. I haven't noticed a drop in flow over the past 3 years, but I might give the showerhead a clean to see in I can increase the flowrate there. However, as I said, today there seemed to be no problem with the boiler.

Who is Barry (does he have a last name) and do you mean Caradon gas services (any contact numbers? in case the boiler stops altogether).

Any other suggestions please?

 

[Agile]

Next time boiler malfunctions do that test! I suspect there may be a problem with the gas supply.

But it could also be asa a result of incorrect gas settings on the boiler for which a CORGI like Barry is needed.

Look up Caradon Gas Services and see how close he is if you need help/

It must be very unusual to have gas but not mains water.

Tony