Boilers
Repair or replace? How to decide
Age on its own is not a diagnosis. Five things worth weighing before you spend money on an old boiler, and the arithmetic we use on site.
Written by the ARA Services engineering team · Updated August 2026
The short answer
Repair is usually right if the boiler is under about eight years old, the fault is one component, and parts are readily available. Replacement becomes the better use of the money once the appliance is past twelve, has broken down more than once in two years, or the repair quote is heading past a third to a half of the cost of a new installation. What matters is which part has failed and what condition the rest of the system is in.
1. What has actually failed
The single biggest factor is the part, not the birthday. Wear items are worth changing on almost any boiler still supported by its manufacturer. Structural failures rarely are.
Usually worth repairing
Thermistors, fans, pressure sensors, expansion vessels, diverter valves, pumps and PCBs — parts that fail from ordinary use and can be changed in a visit.
Usually the end of the road
A leaking or corroded heat exchanger, a failed gas valve on an old appliance, or a case that has been repaired repeatedly. High parts cost, high labour, and rarely the last fault.
Been quoted for a part and want a second opinion? Read us the part and the model.
077 2715 47462. Whether parts are still made
Support is what keeps an older boiler viable. Pre-2005 non-condensing appliances and discontinued ranges increasingly need parts sourced specially, which means longer without heating and more labour on the invoice for the same fault.
If the engineer cannot get the part inside a couple of days in winter, that is a practical argument for replacement quite separate from the price.
We carry the parts that fail most often, so most repairs are done on the first visit.
Boiler repairs3. The arithmetic
Divide the repair quote by the cost of a like-for-like replacement. Somewhere between a third and a half, replacement starts to win — and the older the appliance, the lower that ratio needs to be to justify spending on it. A £400 repair on a six-year-old boiler is easy; the same £400 on a fifteen-year-old boiler buys you one winter.
Compare like with like. Check what each quote includes: diagnosis, labour, parts, VAT and re-testing on the repair side; boiler, flue, controls, filter, system clean, commissioning, warranty registration and Building Regulations notification on the replacement side.
Ask for both prices in writing. We quote the repair and the replacement on the same visit.
Call 077 2715 47464. Breakdown history and the wider system
One call-out is a fault. Three in two winters is a pattern, and the next part is usually already on its way out. It is also worth looking past the appliance: sludge, undersized pipework and a system full of corrosion will shorten the life of a new boiler exactly as it shortened the last one.
Households change too. An extra bathroom or a loft conversion since the boiler was fitted may mean the existing appliance was never sized for the demand it is now being asked to meet.
If the system is dirty, cleaning it is part of the job, not an upsell after the fact.
Powerflushing and system cleaning5. What we do on the visit
The engineer diagnoses the fault, tells you what the part costs and what the labour costs, and says plainly whether the repair is worth doing. If it is not, you get a fixed price for a replacement with the options set out — like-for-like, a change of system, and where the boiler could go — and no pressure to decide on the doorstep.
Weighing it up? Send us the make, model and age and we will give you a straight view.
Get a quoteRepair or replace questions
Will a new boiler really cut my bills?
A modern condensing boiler runs at around 90 per cent efficiency or better, against roughly 70 to 80 per cent for an old non-condensing appliance. The saving is real but it depends on how much heating you use, and it is rarely the whole reason to replace.
My engineer said the boiler is beyond economical repair. Does that mean it is unsafe?
Not necessarily. Beyond economical repair is a commercial judgement about the cost of putting it right. Unsafe is a separate classification, and if an appliance is unsafe it is turned off and recorded as such.
How long does a replacement take?
A straight combi swap in the same position is normally a day. A change of system or a relocation runs to two or three days, and we tell you which it is before we start.
Can you fit the same brand again?
Yes. We install the main makes and will set out what each carries for warranty, since that varies more than the price does.
Get both prices
Tell us the make, model and what it is doing. We will quote the repair and the replacement so you can compare.