Age alone is not the argument. Six things together are, and most of them show up on the bill before they show up on the boiler.
A boiler rarely stops without warning. It gets slower to respond, dearer to run and harder to find parts for, and any one of those on its own is worth watching rather than acting on.
A well serviced boiler runs 12 to 15 years. Past that nothing fails overnight, but two things change: efficiency drifts down a few points a year, and the manufacturer stops holding spares. Age on its own is not a reason to replace anything. Age plus a second sign below usually is.
One repair is bad luck. Two is a pattern worth asking about. By the third inside two years the sums stop working: three call-outs and parts will clear $600, which is a meaningful share of a replacement, and it buys nothing you keep.
Ask what failed each time. Three different components failing is a system at the end of its life. The same component three times is a fitting fault somebody has not found, and replacing the boiler will not fix it.
Rising bills on unchanged usage is the sign people ignore longest, and it is the one that quietly costs the most.
Compare the same quarter year on year, not the last two quarters. If the house is heated the same way, by the same people, and the figure has moved up more than the tariff has, the boiler is burning more gas to do the same work. That gap only widens.
The flame should be crisp blue. Yellow or orange means it is not burning cleanly, and black or brown marks around the case mean it has been doing that for a while. This is the one sign on the list that is not about money.
Turn it off and ring someone the same day. Do not wait for the service that is due next month.
The first two are safety, and they are not a judgement call. The second two are availability, and they turn a planned replacement into an unplanned one the week the heating goes off.
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A service is $129 fixed and takes 90 minutes. If the boiler has years left in it, we say so rather than quote you for a new one.
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