Annual oil boiler service
Fixed price
Burner strip, nozzle + filter swap, electrode reset, smoke and combustion test, OFTEC service record.
Heating & Gas Services
OFTEC Oil Boiler Engineerinstallation, service & repairfor off-mains Northants & Rutland
Off-mains heating in rural Northants often means oil — and oil boilers need an OFTEC-registered engineer, not a Gas Safe one. We install, service and repair Worcester, Grant, Firebird and Warmflow oil boilers across our rural patch.
- OFTEC Registered Technician
- All major oil boiler brands
- Tank-to-boiler full system
- 12-month workmanship guarantee
OFTEC
Certified technician
All brands
Worcester, Grant, Firebird...
Fixed
Annual service price
12 mo
Workmanship guarantee
Oil boiler — installation, servicing, repair, tank work
OFTEC-registered oil work — different ticket, different process
Oil-fired central heating is the second most common off-grid heating fuel in our patch after LPG — particularly in stone-built villages around Oundle, Oakham, and the Welland Valley where mains gas was never run. Oil boilers are a different beast from gas: pressure-jet burners with electrode ignition, replaceable nozzles, and a whole separate certification body — OFTEC.
Working on oil boilers legally requires OFTEC technician registration (OFT10-105E for service, OFT10-101 for installation, OFT-T100 for tank work). It's not interchangeable with Gas Safe. Our engineers hold the relevant OFTEC tickets alongside his Gas Safe and LPG endorsements — meaning the same engineer covers your gas, LPG and oil work without juggling contractors.
Modern oil boilers (Worcester Greenstar Heatslave, Grant Vortex, Firebird Envirogreen, Warmflow Agentis) are condensing, around 92% efficient, and run on standard kerosene heating oil (28-second). They're reliable when serviced annually — and disastrous when neglected, because dirty nozzles, weak ignition and tank contamination compound fast.
What happens if you wait
Skipped oil services don't fail gracefully — they fail at -3°C in January
An oil boiler that hasn't been serviced for 18 months will usually start with a few nuisance lockouts — symptoms of a clogged nozzle or worn electrodes — before refusing to ignite at all. The pattern is classic: it works fine through summer, struggles in autumn, and won't fire on the first hard frost.
Tank-side problems are the silent killer. Water ingress into a poorly-sealed tank breeds bacteria in the oil (the dreaded 'diesel bug'), which clogs filters and starves the boiler. Plastic tanks crack with UV exposure. Steel tanks corrode from the inside. None of it is visible until the boiler stops.
- Skipped annual service → clogged nozzle → first-frost no-fire
- Water in tank → bacterial growth → blocked filters → starved boiler
- Cracked plastic tank → environmental contamination → major remediation cost
- Worn electrodes → weak ignition → soot in heat exchanger → CO risk
- Wrong nozzle size on replacement → wrong burn rate → wasted oil + soot
- Non-OFTEC engineer working on oil — illegal and warranty-voiding
Our process
From first call to job done — exactly what to expect
- 01
Tank & supply check
Tank condition, supply line, fire valve, filter inspected. We start at the tank, not at the boiler.
- 02
Burner strip & rebuild
Burner removed, nozzle replaced (annual service item), electrodes set to manufacturer gap, fan and pump checked.
- 03
Combustion test
Smoke number test (Bacharach scale), CO/CO2 analysis, flue temperature. To OFTEC technical books.
- 04
System check
System pressure, expansion vessel, controls, F&E tank where applicable, full hot-water and heating function test.
- 05
Documentation
OFTEC service record, written report, sticker on boiler, digital copy emailed. Insurance/warranty proof.
Why customers choose Reactive
No guesswork. No upsell. Just the work, done right.
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OFTEC registered
Our engineers hold the OFTEC technician ticket. Legal, insured and properly trained for oil — not a gas engineer 'having a go'.
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Tank-to-boiler full system
We service tank, supply line, fire valve, filter and burner — not just the boiler casing.
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All major brands
Worcester Greenstar, Grant Vortex, Firebird Envirogreen, Warmflow, HRM. Spares carried for common models.
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Fixed-price installs
Same one-number pricing as our gas work. Tank, line, boiler, commissioning — all in.
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Annual reminder service
Auto-reminder before service due date. We schedule before winter, not in the middle of it.
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Free oil-grade CO alarm
Every install gets a CO alarm rated for oil-fired appliances at the manufacturer-spec position.
In detail
Oil boiler servicing — what's actually done, and why nozzle replacement matters
An oil burner sprays atomised kerosene through a precision nozzle into the combustion chamber, where it's ignited by a high-voltage spark across two electrodes. The nozzle is a wear part — its tiny orifice (typically 0.5 to 1.5 US gallons per hour spray rate) erodes over a year's use. A worn nozzle sprays unevenly, causing uneven combustion, smoke, soot deposits and gradual CO production.
Industry standard practice — and OFTEC requirement — is to replace the nozzle at every annual service, regardless of how it looks visually. Spares cost a few pounds; the boiler runs cleaner all year on a fresh one. Engineers who skip the nozzle to save five minutes are not servicing properly.
The other annual jobs: electrode gap reset (typically 3–4mm depending on burner), flexi-hose check, oil filter cartridge swap, photo-cell clean, fan blade clean. Then a smoke number test using the Bacharach scale (we look for sub-1 on a clean burner), and a CO/CO2 analysis to confirm clean combustion.
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Worcester Greenstar Heatslave
Common across Northants. Electrode and nozzle service-critical. We carry spares.
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Grant Vortex
Wall-hung and floor-standing variants. Reliable when serviced; brittle when ignored.
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Firebird Envirogreen
Popular in stone properties. Different burner head design — needs OFTEC-trained eyes.
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Warmflow Agentis
Good off-grid choice. Standard service intervals apply.
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Tank inspection
Plastic tank crack check, steel tank corrosion check, base / bunding integrity, fire valve test.
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Tank replacement
Old tank decommissioning + new bunded tank install + line + fire valve + commissioning.
Honest pricing
How much does oil boiler service, install or repair cost?
Oil boiler work is priced similarly to gas, with small premiums on installs (oil-spec boilers and tanks add cost). Annual service includes the nozzle and filter swap as standard.
Oil boiler installation
Fixed price
Worcester / Grant / Firebird condensing boiler, full install, system flush, MagnaClean, registered warranty — quoted after free survey.
Oil tank replacement
Fixed price
Decommission old tank, new bunded plastic or steel tank, supply line, fire valve, commissioning.
What changes the price
- Boiler make, model and kW output
- Tank type (plastic bunded vs steel) and capacity
- Distance from tank to boiler
- Existing supply line and fire valve condition
- Whether old tank requires environmental decommissioning
- Annual service plan vs one-off
Free, fixed-price quote — no obligation, no callout fee.
Get my fixed priceAreas covered
Local cover across Northants & Rutland
Oil heating is most common in our rural patch — Oundle, Oakham and the surrounding villages, Welland Valley properties, and the more isolated parts of west Northants. We service across all of it.
Who'll be doing the work
The Reactive engineering team
Our engineers hold OFTEC registration alongside Gas Safe and the LPG endorsement — the full off-grid trifecta. Most rural Northants homes end up needing one of those tickets at some point, and we cover all three under one phone number.
- OFTEC Registered Technician (OFT10-105E, OFT10-101, OFT-T100)
- Gas Safe Registered
- Worcester Heatslave trained
- Grant Vortex trained
- Free oil-grade CO alarm with install
FAQs
Questions we actually get asked
Anything not covered here? Pick up the phone — straight talk, no salesperson in the middle.
Call 07342 043953Ready when you are
Reliable oil heating, properly serviced. Book a service.
OFTEC registered, all major brands, free oil-grade CO alarm on every install — across rural Northants, Rutland and Leicestershire.
Last updated May 2026 · Reactive Gas Heating and Plumbing Services Limited · 9 Rutherford Court, Corby NN17 4SJ · Gas Safe Registered · OFTEC Registered · Checkatrade Verified