HERTFORDSHIRE, BEDFORDSHIRE & CAMBRIDGESHIRE
Boiler Repair in Dunstable
Affinity Water classes Dunstable’s supply as very hard, and many estate heating systems here are decades old. Between them they explain most of the breakdowns we see. We find the fault for a fixed fee, then price the repair.
310 mg/l, from the water company itself
Affinity Water publishes a report for its Dunstable supply zone. For 2025 it gives a mean total hardness of 310 mg/l as calcium carbonate, from six samples ranging between 298 and 323. On Affinity’s own scale, anything over 300 is very hard.
The neighbouring Caddington and Eaton Bray zone is harder still, at 348 mg/l. These are zone figures rather than a test of your tap, but they explain why scale features in so many of the repairs we carry out here.
Not sure whether your boiler has any scale protection? Look for a small canister or cartridge on the cold pipe running into it. If there is nothing there, we will check on the visit and tell you whether it is worth adding.
Get a fixed price before we start
Call and talk to an engineer, or send us the details and we will come back to you with a price.
How very hard water breaks boilers
The hot water side
On a combi, scale coats the plate heat exchanger that heats tap water. The result is hot water that surges and fades while the heating carries on as normal.
The main heat exchanger
Where scale lines the waterways, water boils in pockets and the boiler kettles, rumbles or bangs as it fires. Left alone, it overheats and locks out.
Valves and sensors
Diverter valves stick, pressure relief valves start to let by and temperature sensors read wrongly once they are furred up.
The faults we are called to most
No heating, or radiators cold at the bottom
No hot water while the heating still works
Pressure falling and needing regular top-ups
Lockout codes that return after each reset
Kettling and banging from inside the casing
A frozen condensate pipe after a hard frost
A noisy pump, or water weeping from under the boiler
Radiators cold at the bottom are rarely air. In older estate systems it is usually sludge settling where the water moves slowest.
Estate heating that has seen a lot
Plenty of the houses built here between the 1930s and 1970s still run on 8mm and 10mm microbore pipe, and some keep gravity circuits and single feed cylinders. Narrow pipe clogs with sludge faster and starves the boiler of flow, which trips it out. A pump working against partly blocked pipe also runs hotter and wears sooner.
So a repair here often means looking past the boiler. If the pipework is the real problem, we will say so rather than fit a part that fails again within the year.
Noises, drips and tired pumps
A pump that hums, grinds or rattles may have air trapped in it, may be set to the wrong speed or may simply be worn out. We check which before replacing anything, because a new pump on a system full of sludge will not last.
Water under the boiler needs looking at quickly. It can be the pressure relief valve discharging, a weeping seal or, less often, a heat exchanger that has started to leak. Turn the boiler off, put a tray under it and ring us.
Diagnosis before any part is ordered
Pressing reset clears a code but not what caused it. We read the boiler’s fault history, test the part the code points to, then check gas pressure, flue, pump, expansion vessel and controls to see whether something else made it fail.
Only when we know the cause do you get a price. Nothing is fitted until you have agreed to it, and if the job turns out different from what was expected, the engineer stops and prices it again.
Diagnosed properly before anyone quotes
A fixed diagnostic price, all makes and models, and a straight answer on repair or replace.
One fixed fee to find the fault
Our Gas Safe diagnostic is £150 + VAT (£180 including VAT). It covers coming out, finding the fault and any minor work without parts, up to an hour on site.
Say yes to the repair during that visit and £70 of the diagnostic comes off the repair. Out of hours, gas work is £225 + VAT for the first hour and £75 + VAT for each half hour after, with the out of hours call-out on top, all confirmed before anyone travels.
Checks that are safe to make first
Look at the pressure gauge and, if it has dropped, top up through the filling loop to the level in your manual. Check the programmer, the room thermostat and the fused spur that powers the boiler, and try one reset.
If a condensate fault appears in freezing weather, pour warm water, not boiling, along the white plastic pipe where it runs outside.
Beyond that, stop. Taking the casing off or touching the gas valve, burner, fan or flue is legally work for a Gas Safe registered engineer only.
When a new boiler makes more sense
One failed part on a sound boiler is a repair, and we will tell you so. A heat exchanger scaled beyond saving, parts that are scarce, or a boiler still running on an old gravity setup can change the answer.
In that case you get the repair price and a replacement price side by side. Swaps start from £2,375 + VAT (£2,850 including VAT), with the old boiler removed and next day installation on most standard replacements, subject to survey.
Many manufacturers expect water treatment in hard water areas as part of their warranty terms, so any new boiler here should go in with scale protection. See our boiler installation page.
Every make, and a card at the door
Any common make is fine by us; Vaillant, Ideal and Worcester Bosch are simply what we tend to install. Every engineer we send is our own employee and carries a Gas Safe ID card under registration 956889, so ask to see it before anyone opens your boiler. Our vans are fully stocked, so common parts are often on board and the repair can be finished on the first visit.
Once the repair is done, the boiler is tested on heating and hot water, and the work carries our 12 month labour guarantee.
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Why choose Vantage
Rated 4.9 on Google from more than 700 reviews across Google, Checkatrade and Trustatrader. Qualified, accredited engineers, a fixed price before any work begins and a labour guarantee on every job, from an established local company with an office team you can actually reach. No job too small.
Gas Safe registered
Company registration 956889. Every gas engineer carries their own Gas Safe ID card, and you can ask to see it.
Refcom F-Gas certified
REF1024550. Legally required for air conditioning installation and servicing, and we hold it.
CHAS Elite accredited
Veriforce CHAS assessed for health and safety, which is why commercial clients and landlords use us.
City & Guilds and BPEC qualified
Qualified, insured engineers on every job. No subcontracted strangers.
700+ reviews, 4.9 on Google
Across Google, Checkatrade and Trustatrader. Read them before you book.
Labour guarantee on every job
12 months on repairs, installations and everything else. Two years on a full bathroom refit. If anything we did develops a fault, we come back and put it right.
Fixed price before we start
The price is agreed with you before any work begins. No hidden extras on the invoice.
24/7, answered by a person
The emergency line is answered every day of the year by someone who can send an engineer, not a call centre.
Fully stocked vans
Five vans carrying the parts that fail most often, so most jobs are fixed on the first visit.
An office team behind every job
An established local business with multiple engineers and a dedicated office team to keep you informed.
Vaillant myREWARDS and Ideal Max accredited
Accredited installer status means extended manufacturer warranties on the boilers we fit.
Emergency response within the hour
Our average response to an emergency call is under an hour across Hertfordshire, Bedfordshire and Cambridgeshire.
Trusted & Accredited Professionals
Frequently asked questions
How hard is the water in Dunstable?
Affinity Water’s 2025 report for the Dunstable zone gives a mean of 310 mg/l, which it classes as very hard.
Why does my combi hot water keep going hot and cold?
In water this hard, scale on the plate heat exchanger is the usual cause, and it can often be repaired.
What does the £150 + VAT diagnostic include?
It pays for the visit, the fault finding and any small job needing no parts, for up to an hour. It is £150 + VAT (£180 including VAT), and £70 comes off a repair done on the same visit.
Why are my radiators cold at the bottom?
Usually sludge rather than air. Bleeding will not shift it, but cleaning the system can.
Will you repair a boiler on microbore pipe?
Yes, and we check whether the narrow pipework caused the fault so the repair lasts.
Is it worth repairing a boiler over fifteen years old?
Sometimes. If the heat exchanger is sound and parts are available, a repair can still be good value, and we give you both prices.
Can I top up the pressure myself?
Yes, using the filling loop as your manual explains. Needing to do it often means water is escaping somewhere on the system.
Do your engineers carry Gas Safe cards?
Yes, every one of them, under registration 956889. Ask to see it.
How long is the repair guaranteed?
Our labour carries a 12 month guarantee.
Why does my boiler stop on frosty mornings?
The condensate pipe outside has probably frozen. Thaw it with warm water along its length, then reset the boiler once.
Does a boiler visit cost more at the weekend?
Outside weekday hours the gas rate is £225 + VAT for the first hour and £75 + VAT for each half hour after, with the call-out added, and you hear it before we set off.
Areas we cover around Dunstable
We repair boilers across LU5 and LU6, from Northfields and Beecroft to Downside, Jeans Way, the Poynters and Hadrian estates, the Lake District Estate and the Victorian streets around Victoria Street.
Houghton Regis next door is covered too. If a leak or burst comes first, our emergency plumber in Dunstable page explains what to do.
Boiler playing up in Dunstable
Call 01462 506 374 and we will send one of our own Gas Safe engineers, with the fixed diagnostic price confirmed first.
Related services
Annual service, £99 + VAT
Fixed price swaps from £2,375 + VAT
Sludge out, heat back, from £595 + VAT
Cold radiators, pressure loss, noises
Fault codes and guides
Every rate, published