Sorry, this isn't directly DIY and is probably a little longer than necessary, but I would like to understand how this works before I take the decision on whether to get my boiler repaired or replaced.
I have a Worcester 24i boiler in my house, which is a four bedroom mid-terrace with ten radiators, a bathroom, an en-suite, a kitchen and a laundry room (with sink and washing machine).
Lately the boiler's become unreliable. Sometimes I'll run the hot tap and get nothing but cold water, sometimes the CH wont come on, sometimes when I try to run a bath it'll start hot and then, after a few minutes, the water will run cold. The same thing might happen while I'm doing the washing up and it'll take me a few tries faffing around with the taps and switching the boiler on and off, before I can get the hot water flowing again. I'll look through the peephole and see no fire.
It's a combi boiler, so I assume it should keep heating the water for as long as I require.
A plumber came round earlier today and advised that there were probably three issues: the PCB (relays were chattering as he played with the timer), the clock (clicking noisily as a matter of course and cutting in and out when he pressed on it) and the fan (noisy bearing and possibly not creating sufficient pressure) and that these would cost approx £500+VAT to sort.
He suggested that it wasn't worth the cost of repair as more repairs would be likely to follow down the line due to the age of the boiler, which he put at 7-8 years old.
About 1 year ago, a different plumber visited to rectify another problem: I had complained that the flow of hot water in the upstairs bathroom was too slow. He removed a plastic thing from the boiler which he referred to as the "flow regulator" and this seemed to do the trick.
Today's plumber says that this was illegal insofar as, if the previous plumber were Corgi registered, he would never have made this modification which is against the manufacturer's spec and, therefore illegal and, if he weren't Corgi registered, he shouldn't have touched the boiler in the first place. In removing the plastic flow regulator, my boiler could overheat, catch fire and I would not be insured for any of the damage, because of the illegal removal of the flow-regulator.
His best advise was that the existing boiler isn't sufficient for a house of this size anyway and that removing the flow-regulator was, in effect, a botch to keep me happy, on the cheap. He stated that the boiler delivers 9 litres/minute which isn't enough for a house of this size.
Now I know very little about this sort of stuff and I hate not understanding these things for myself. My unqualified logic would be that the boiler has been big enough for several years and that it should be big enough after the faults have been rectified. But the plumber advises that the flow-regulator removal is proof of the existing boiler's inadequacy - if it had the required capacity, the flow regulator would not have been removed to rectify the slow hot water in the bathroom, in the first place, and having no flow-regulator now is dangerous.
I'd like to add an en-suite shower to the master bedroom soon and would not like to spend on an aging boiler today, only to have to replace it in a few months with a boiler with a greater capacity, in order to accommodate what I hope will include a power-shower and another sink. But I don't want to spend the £1300 quoted for a new boiler+fitting, if I've simply misunderstood the plumber's advise and a repair+service will do the trick.
Please can those of you with experience explain to me whether my concern should be to get the boiler repaired and serviced on the basis that service is required after 7-odd years but the boiler is adequate or whether I should be looking to replace the boiler so as to improve existing hot water service and provide for the future.