Your AI onsite guide

Find the fault before you ring the helpline.

Every manufacturer manual, fault code and service figure for 1,100+ gas boilers, in one place. And free. Stuck on one? Ask Flint and get a straight answer off that boiler's own manual in seconds, page and all. An extra pair of hands, not a replacement for one.

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No card to start. The manuals, fault codes and calculators are free for good.

Flint's Service Info screen for a Worcester Bosch Greenstar 8000 Life Combi: commissioning at a glance, showing CO2 max 9.5%, CO2 min 8.6% and a CO/CO2 ratio of 0.004 for natural gas, CO max 250ppm commissioning and 75ppm service, each block citing manual page 51, with the LPG figures below.
Real screen · every figure cites its manual page
48
manufacturers
1,100+
gas boilers
50,000+
fault codes, decoded
1 tap
from any figure to its manual page

A simple service, the hard way

You've been here.

01There's no single home for manuals. You Google the model, dig out a PDF, and hope it's the right variant.
02Then you scroll 90 pages for one figure, on your phone, in a cold loft. You read it twice and still miss it.
03How do you get this one into service mode? Every make's different, and nobody remembers them all.
04You want the CO and CO₂ min/max, the gas rate, the gas valve settings. Three sub-menus deep, if it's there at all.
05So you ring the helpline. Hold music. Customer watching you. And the answer doesn't always land.
06And when you find something genuinely unsafe, you want the classification right, first time, with the customer stood there.

Flint gets you the same answer in seconds, not a phone queue.

What's inside, free

The whole job, in your pocket.

01
1,100+ boilers, one searchManuals across all 48 major makers, with their logos on the home screen so you find one at a glance. Search by model name, GC number or the maker's own code.
02
Search inside the manualFull-text search within the PDF. Jump straight to the page you need instead of thumbing through ninety of them.
03
Fault codes, decodedOver 50,000 codes: what it means, the likely cause, the parts most often replaced, and a steer on the repair cost. Grouped and in order, with a filter that matches what the boiler actually shows. Where the manual has fault-finding flow charts, those pages are linked too.
04
Boiler age, off the serial numberType the serial from the badge and Flint works out whose boiler it is and when it was built, showing its working so you can check it. Where a maker doesn't publish the rule, it says so and gives you their own route rather than guess a year.
05
A GC number we hold no manual for still tells you somethingType a GC off the badge and Flint names the appliance from the official product register: make, model and the years it was built. It says plainly that the manual isn't in yet, instead of leaving you wondering whether you mistyped it.
06
Four calculators that earn their placeGas rate (metric and imperial), CO/CO₂ ratio pass or fail, temperature rise (ΔT), and expansion-vessel sizing.
07
Every maker's helpline, one tapThe UK technical line for every manufacturer, built in. Tap to call, no hunting for the number mid-job.
08
Your workbenchFavourites, recently-viewed, and private notes on any model: customer details, parts fitted, settings, kept on your device.

Not just the PDF

The manual, structured.

Flint lifts the figures out of the manual and lays them out like instrument readouts, so a service isn't a scrolling exercise. Open any section and the data is already there.

Service mode Combustion targets Gas & burner pressures Gas valve settings Technical data NTC sensor tables Spare part numbers Wiring diagrams
The right number for this boiler, not its family. A Greenstar 12 Ri ErP wants 9.65% CO₂ at max rate. The 15/18/24 Ri wants 9.8%. The badge on the front won't tell you which.
What the maker asks for, not the rule of thumb. Worcester's Ri manual wants CO under 200 ppm where the generic figure is 350. Flint gives you the one that's actually in the book.
Both rates, properly. CO₂ and CO targets at max and min, plus the ratio to check against at each. The service-mode sequence for the boiler in front of you, not a generic one.
Every value carries its exact manual page, so you can check it against the book in a tap.
Flint's home screen: a search box over the boiler catalogue with the manufacturer list beneath.
Search by model or GC
A Flint boiler page: model name, GC numbers, boiler type and the service sections for that appliance.
The boiler in front of you
Flint's fault code list for a boiler, with each code expandable to show what it means and the likely cause.
Fault codes, decoded
Flint's gas rate calculator: timed meter test inputs producing gross and net heat input in kilowatts.
Gas rate, worked out
Flint Pro

A second opinion, in seconds.

Nobody's saying a chatbot knows your trade better than you do. Flint just reads the manual faster than you can. Ask about the boiler you're stood at, or tap a fault code and ask what's worth checking, and you get a straight, step-by-step answer off that model's own manual, with the page to prove it.

YouPressure keeps climbing. Customer's already had the heat exchanger and expansion vessel done. What else?
Flint
  1. Filling loop passing. Even slightly, it'll creep the pressure up. Check it's fully closed and not weeping.
  2. Expansion vessel pre-charge not set to the cold-fill pressure, or vessel undersized for the system volume.
  3. Vessel isolation / waterlogging on an external vessel, or a dead-leg on the zone valve holding pressure.

Sources: Greenstar 30i installation manual, p.42 (filling), p.51 (expansion vessel).

Unsafe situations, classified

Tap through what you've actually found and Flint gives you the IGEM/G/11 classification with the required action, numbered, in the order you do it. Where the incident is RIDDOR-reportable it says so and gives you the deadline.

IDARNCS

It's a paraphrased summary of IGEM/G/11 Edition 2, written for speed on site. It isn't the standard itself and it doesn't replace your judgement. Confirm the classification yourself before you leave.

The full service data

Combustion targets at max and min, gas and burner pressures, gas valve settings, NTC sensor tables, spare part numbers and wiring diagrams, laid out as figures rather than a PDF to scroll. Every value carries its manual page.

It won't go past the manual

Answers come from that model's manufacturer manual and a gas fault-finding reference, built with Gas Safe registered engineers. It won't contradict the manual or invent a procedure. The only method it'll walk you through is the standard, safe way to carry out a test.

It shows its working

Step by step, in real figures, with the page cited, exactly like a good answer off the phone. You can check every line against the book.

You're the engineer. Flint just fetches.

It doesn't decide, it doesn't sign anything off, and it doesn't authorise the work. The manual gates that on a competent person with a conforming analyser, and that's you. Flint only gets you the figures faster.

Pricing

Free where it helps. Paid where it pays you back.

Free app
£0forever

Every manual, fault codes, boiler age from the serial, the four calculators and every maker's helpline. The stuff other apps put behind a subscription, free for good.

Pro
£4.99/ month
or £49 / yearBest value

Ask any boiler a question and get a manual-grounded answer, plus the unsafe-situations classifier and the deeper structured service data. One saved callback covers the year.

Get Flint free Start free. Upgrade to Pro inside the app, whenever it earns its keep.

Built for UK gas engineers.

Servicing and repair, domestic gas boilers. If you're a few years in, it's the mate you'd have rung, without the hold music. If you've been on the tools thirty years, it's a sanity check and every manual in one place, instead of hunting each one down. Either way it's fast, one-handed, and grounded in the manufacturer's own data.

Before you ask

Straight answers.

Is my boiler in there?

1,100+ gas boilers across 48 manufacturers, from the big names to the ones you'd forgotten existed. Search by model name, GC number or the maker's own code. If one isn't in there yet, tell us in the app and we'll add it.

Is it actually free?

Yes. The manuals, fault codes, the four calculators and every manufacturer's helpline are free, and stay free. Pro is £4.99 a month or £49 a year, and it adds Ask Flint plus the deeper structured service data. No card to start.

Where do the AI answers come from?

Every Ask Flint answer is built from that model's own manufacturer manual and a gas fault-finding reference put together with Gas Safe registered engineers. It cites the manual page so you can check it, and it won't go past the manual or invent a procedure. You're the engineer signing it off, not the app.

Is the unsafe situations tool official?

No. It is a paraphrased summary of IGEM/G/11 Edition 2, written so you can tap through it on site and get the classification (Immediately Dangerous, At Risk or Not to Current Standards) with the required action in order, plus a flag when something is RIDDOR-reportable. It is guidance, not the standard itself, and it does not replace your judgement: confirm the classification yourself before you leave the installation. It is part of Pro.

Can Flint tell me how old a boiler is?

Type the serial number off the badge and Flint works out the make and the date of manufacture, and shows the arithmetic so you can check it. It only decodes where the manufacturer publishes the rule. For the makers who don't, it says so and gives you their own route, because a confident wrong year is worse than no answer when there's a warranty or a replace-or-repair quote riding on it. Free.

What does it run on?

iPhone and Android, and the browser at app.flintfix.com. One account works across all three.

Get the app

Be the engineer who walks in already knowing.

Get it onGoogle Play Download on theApp Store

Prefer the browser? Open Flint at app.flintfix.com

Free to start. Manuals, fault codes and the calculators are free for good.