Boiler GC number lookup: find the GC number for any make and model

Every gas appliance sold in the UK carries one, most engineers can point at it on a plate, and almost nobody is taught what it is. This page is the reference: what the number means, where each make puts the plate that carries it, and a lookup of the published Gas Council numbers for ten makes that turn up on domestic work. Every number in the tables was read out of the manufacturer's own manual and is listed under Sources, so you can check any row against the book it came from.

What is a GC number?

A GC number is the Gas Council number, a seven digit appliance reference written in the form 00-000-00 that identifies one exact appliance variant. Gas appliances sold in the UK are registered with one, and it stays with the appliance whatever the range is called in the current brochure. That is the whole point of it. Two boilers can wear the same range badge, share a marketing name, take different parts and carry different GC numbers, and the number is what settles which one is actually on the wall. It is also the identifier a merchant or a parts catalogue will ask you for, because a model name on its own does not narrow an order down to a single variant.

The number is not something you work out. It is assigned to the appliance and then printed in two places: on the data plate fixed to the boiler, and in that model's installation instructions, usually within the first page or two. Where the plate has faded or been painted over, the manual is the dependable route, and the tables further down this page are those manuals read for you.

Where is the GC number on a boiler?

On the data plate, and the only thing that changes between makes is where that plate is fixed. Below is where each make puts it, at the level you need to find it on site. Each make has its own page with the range by range detail, a diagram of the plate positions and the serial number decode.

Worcester Bosch prints the model, the GC number and the serial on one badge, and moves it by range. On the Greenstar 2000 and 4000 it sits centrally on the bottom of the appliance, in line with the control panel. On the 8000 Life and 8000 Style it is on the frame of the front cover. On the CDi Classic, CDi Compact, Si Compact, i and Ri, Worcester calls it the boiler or appliance identification label and puts it on the fascia. One clear photo of that badge gives you everything a record needs.

Vaillant splits it across two plates on most ranges. The data plate is on the underside of the boiler on the earlier ecoTEC plus, the open vent, the ecoTEC exclusive, the ecoFit pure and the ecoTEC pro; on the current ecoTEC plus CS/1-5 range there are two, the main one on the rear of the electronics box and a second on the top. The serial is repeated at the front, either on a plastic label behind the front flap or on the underside of the front panel, so check the front before you assume the plate has been taken off. Vaillant lists a GC no. field in the ecoFit pure and open vent plate keys, and prints the number in the manual for every range.

Baxi puts the data plate above the boiler controls on the current Combi 2 platform, the 800, 600 and Assure 500, and on the top part of the boiler on the 800 System 2 and the 400 Combi 2. On the older ranges it is further in: the lower panel with the control box dropped on an EcoBlue Advance, the control box itself with the outercase off on a Duo-tec Compact, the inner door panel on a Platinum+ 40. A boiler ID label by the cable gland underneath, or the user information label, repeats the serial.

Glow-worm is the simplest to remember and the most awkward to reach: on the Energy7, Ultimate 3, Easicom 3, Betacom 4 and Essential the plate is on the underside of the boiler, fitted at the factory. The Compact and MicraCom are the exception, with the plate on the rear of the electronics box and on the upper side of the product. On a legacy Betacom C the data label is on the control box back cover. The plate carries the GC number beside the serial, labelled GC no.

Potterton and Main put the data badge on the control box behind the outercase on the Assure Combi and the Eco Compact, and repeat the model, serial and GC number on an information label under the outercase that you can read with the case on. Viessmann's own serial number locator puts the plate on top of the boiler on the Vitodens 050-W, 100-W Heat Only and 200-W, and behind the front panel on the 100-W combi and the 111-W. Alpha draws the data label beside the electrical connection in the E-Tec Plus NX manual. Vokera and Ferroli name the data plate throughout their manuals without saying where it is fitted, so look underneath first. Ferroli prints the GC number on the cover of its Bluehelix manuals, and Vokera prints it on some manual covers and against every current model on its literature page.

What is the difference between the GC number, the serial number and the model?

They answer three different questions: which variant, which individual appliance, and which family it belongs to. Mixing them up is what puts the wrong part in the van, so the table below sets each one against what it identifies and what it is actually for.

How do I look up a GC number by make and model?

Match the designation on the plate, or on the front of that model's manual, against the tables below. Each one is read straight from the manufacturer's own installation instructions, user guide or literature page, listed under Sources. Look the boiler up by the code the factory uses rather than by the marketing name where the maker gives you one, because that is the key the numbers are indexed by: Worcester by the appliance type on the badge, Vaillant by the VU or VUW type designation, Glow-worm by the product article number. Where a range is missing from a table, the number is in that model's manual rather than lost.

VU is a system or open vent boiler and VUW is a combi, so the letters alone tell you which family a Vaillant belongs to before you reach the number. For the earlier ecoTEC plus ..6/5-5 generation and the ecoTEC pro, the Gas Council Number table sits in the notes on the documentation near the front of that model's installation and maintenance instructions.

Baxi's discontinued ranges are still on plenty of walls, and the same manuals give 47-077-14 to 47-077-17 across the EcoBlue Advance Combi 24, 28, 33 and 40, then 47-077-68 to 47-077-70 across the Duo-tec Compact Combi 25, 30 and 36, and 47 077 41 for the Platinum+ 40 Combi. Those are published as spans across the outputs rather than model by model, so take the number for a specific appliance off its plate or its manual.

The Assure Combi manual also lists a 36 and the LPG versions under their own numbers, and the older Gold, Promax HE Plus and Performa ranges are on the Potterton page linked above.

The Vitodens 200-W installation and service instructions carry no Gas Council number section at all, so on a B2HF or B2KF take the number off the type plate. The numbers do not follow the output in order, which is one more reason to read the row rather than guess the next one along.

Alpha prints its numbers with spaces rather than hyphens, which is the same number written a different way. The earlier E-Tec, InTec, CD and Pro Tec ranges are on the Alpha page linked above.

The older Vokera, Ferroli and Main ranges, from the Compact A and Unica HE to the Optimax, Modena and Main HE, are on each make's own page with the manual each number came from. Where a make or a range is missing here, take the number off the plate or out of the installation instructions for that model, not off a factor's listing, because a GC number copied from a listing is a guess with a plausible shape.

What if the data plate is unreadable?

Go to the manual for that model, which is where the number is published in the first place. Nearly every manual behind the tables above prints the GC number on the cover or in the first few pages, alongside the appliance type or article number (the Viessmann Vitodens 200-W book is the exception, and several current Vokera books leave the number to Vokera's literature page), so if you can name the model from the case badge, the boiler controls or the Benchmark logbook, the manual gives you the number without a plate at all. Each maker keeps a free literature library online, and those are listed under Sources.

Where the model itself is in doubt, the serial number is the next thread to pull. It is usually repeated somewhere other than the data plate, on a label behind the front flap, a magnetic card supplied with the boiler, stickers on the electronics box or a user information label, and each maker's technical helpline can identify an appliance from it. That call is also the only route that is authoritative when the plate has gone entirely.

Two public databases get suggested for this, and it is worth being clear about what each one actually does. Gas Safe Register's public lookups cover businesses and engineers rather than appliances: you can check a registered business by trading name or registration number, check an individual engineer by the seven digit licence number on their ID card, and look up a notified installation by its address to order a duplicate Building Regulations compliance certificate. There is no public appliance or GC number database there. BRE's Product Characteristics Database at ncm-pcdb.org.uk is the other, and it is searchable by brand name, model name and model qualifier; it holds validated performance data submitted by manufacturers, which makes it a way to confirm a brand and model name exists as the maker registered it. It does not publish GC numbers. For those, the manual and the helpline are the routes that work.

Does the GC number change between natural gas and LPG?

Yes. The LPG version of an appliance carries its own GC number, and that is exactly the kind of variant the numbering exists to separate. Worcester Bosch shows it plainly: a 30kW Greenstar 4000 combi is 47-800-32 on natural gas and 47-800-33 on LPG, one digit apart and a different appliance. The 8000 Style also comes in CB variants with a separate set of numbers again. Every figure in the Worcester table on this page is the natural gas number, so on an LPG installation read the plate rather than the table, and check the gas type on the badge before you order anything.

Why does the GC number matter on a CP12?

Because it is the sharpest description of the appliance available to you, not because the law names it. Regulation 36(3) of the Gas Safety (Installation and Use) Regulations 1998 sets out what a landlord's gas safety record must contain, and on the appliance it asks for a description of and the location of each appliance or flue checked, alongside the date, the address, the landlord's details, any defects and the remedial action taken, and the engineer's name, signature and registration number. No GC number, no serial number, no model.

That leaves the quality of the description to you, and next year it is the only thing anyone has to work with. A record saying combi boiler, kitchen tells the next engineer almost nothing. A record carrying the make, the model as the plate writes it and the GC number in full identifies the exact appliance variant a year later, when the boiler may have been swapped, when a defect is being argued about, or when a landlord asks whether the thing on the wall is the thing that was checked. It also travels: the same number that settles a parts order settles which appliance was on the record.

The reading is the easy part. Copying it accurately, upside down under a boiler at the end of a long day, is where digits go missing and a 47-800-32 becomes a 47-800-33. Manifold's PlateScan reads the make, model, GC number and serial straight off the data plate with the phone camera for you to confirm, so what lands on the record is what the plate says, and this year's reading sits next to last year's when an appliance's history needs checking.