Is it leaking water? Once the water-jacket of a boiler has rusted through and is leaking I’m afraid you’ve really got no choice but to change it. If water is not leaking all over the floor, you have the luxury of time to consider and decide what is right for you. Here are a few things for you to consider…
Isn’t a new boiler more efficient and therefore cheaper to run?
Yes, modern ‘condensing’ or ‘high efficiency’ boilers are much more efficient than ‘non-condensing’ or ‘standard efficiency’ boilers. Typically in an older, non-condensing boiler the gases leave the flue between 180oC & 220oC, but on a condensing boiler the flue gases emitted are around 60oC to 70oC. Given the oil is burnt around 1500oC in both sorts of boiler, that means you are wasting an average of 130oC every moment an old boiler is running, straight away. On average a new condensing boiler will be 10-15% more efficient.
BUT… just because it’s cheaper to run, doesn’t mean fitting a new boiler will be ‘cheaper’. At time of writing a 20kW oil boiler (not a combi) costs around £3400 supplied and fitted. If you use around £1500 of oil a year and save 10% on your fuel bill, you will save £150 per year. Therefore, on oil savings alone it will take 22.6 years for you to pay for the new boiler.
Will a new boiler will emit less CO2 when it’s running? Yes, but how much less compared to the manufacture and delivery of a new boiler??? I’ll leave that one for you to discuss.
A Planned change rather than an emergency change?
If you have an older boiler, it can get to that stage where it breaks down a couple of times here and there, then this part need replacing, then that part needs replacing. Pretty soon you’re seeing your Oil Boiler Engineer a bit more often than you would prefer and you can soon find you’re spending more and more keeping your old boiler going. If your boiler is at this stage in it’s life it’s best to start thinking about replacing it and, in my experience, it’s best to plan when that will be rather than waiting until the boiler completely fails (usually in the middle of winter when all the Oil Engineers are booked up solid for weeks and cannot fit in a boiler change). Then you could easily find yourself in a situation with no choice but to keep making do and mend. Soon you’ve spent 25% of a new boilers cost in parts & labour.
Having a new kitchen, extension of work done? If your boiler is located within the area you are having refurbished, I really would recommend trying to factor a new boiler into the budget. Do you really want to have to take out an old boiler an replace it a couple of years after you have just had a new kitchen fitted? Bear in mind that kitchen fitters will have no qualms about boxing in a boiler and making it impossible to service properly (yet alone remove and replace it) and that modern condensing boilers require different flues to the old non-condensing boilers!