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What a type 21 radiator is

A type 21 radiator is a double panel with one set of convection fins, the single convector layer on that code [S6]. In Cheshire, the fitting quote should name the height, the length and the heat output, and say whether adding the radiator needs building regulations approval [S1].

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By the QuoteZila editorial team. Editorial policy.

What a type 21 radiator is

A type 21 radiator is a double panel with one set of fins. In the Department for Business, Energy and Industrial Strategy report on domestic heat distribution, published in February 2021, that is the description next to type 21: a double panel with one set of fins [S6]. Type 20 in the same table is a double panel with no fins, and type 22 is a double panel with two sets of fins [S6].

Those fins are the convector layer. The report says panel radiators usually have convection fins welded between the panels, or on the back of a single panel, to move air [S6]. It also says the wide range of output among double-panel radiators is there because some have two convectors and others only one [S6]. A type 21 is the double panel with one of those convector sets, not the double panel with none and not the double panel with two [S6].

Where a double panel fits

The same report says double-panel radiators take up less wall area than single-panel radiators with the same heat output [S6]. A type 21 is the double-panel code with one set of fins, so it sits with those double-panel radiators rather than with a single panel [S6]. Column radiators, designer radiators and towel rails are described separately in the report [S6].

Say which wall the radiator sits on, and what is already in the way: a shelf, a curtain or a cover. Those facts change what will fit. They are not a heat-loss calculation. Ask the engineer which output they are allowing for the room, and ask them to show where that number comes from.

Size and the written quote

The BEIS study measured each radiator, because the panels, the fins and the size are what set the heat output [S6]. It used supplier literature for a range of sizes, rather than one national size for a type 21 [S6]. Write the height, the length and the pipe centres on the quote, and write the output the engineer is using. Two quotes that both say "type 21" and nothing else are not yet the same radiator.

Bring a tape measure figure you took yourself, marked approximate, and a photo of the pipes where they come out of the wall or the floor.

In Crewe, Nantwich and Sandbach, the fitting price is the written price for that room. Citizens Advice wants a fixed price in writing, from at least three traders where you can get them, and a clear answer on VAT [S4]. GOV.UK says a business must register for VAT when taxable turnover for the last 12 months goes over £90,000 [S5]. If a deposit is hard to avoid, do not go above 25%, and keep the receipt [S4]. Ask the quote to say whether the pipes move, who takes the old radiator away, and whether the visit includes the boiler. A shop code is not that price.

Adding a radiator and building regulations

GOV.UK's page on building regulations approval includes adding extra radiators to a heating system among alteration projects that might need approval [S1]. It also says the list is not everything, and that you should check with a building control body if you cannot decide [S1]. Using a competent person scheme registrant means you do not have to arrange the approval yourself [S1].

The booklet on home replacements and repairs gives "addition of a radiator to an existing heating system" as an example that may need telling to a building control body, with a star to say it may not in some circumstances [S2]. Read both pages, then ask. A shop code is not a substitute for that question.

GOV.UK: building regulations approval. QuoteZila is not affiliated with this organisation.

Gas work on the boiler

If the system is heated by a gas boiler and the visit goes onto that appliance, HSE's domestic gas FAQ is the rule: the person employed must be Gas Safe registered and competent [S3].

Gas Safe Register. QuoteZila is not affiliated with this organisation.

HSE says that if you suspect a gas appliance is unsafe, turn it off and do not touch it until a registered engineer checks it [S3]. A cold radiator is not, on its own, that suspicion. A smell of gas is a different phone call. Do not vent a radiator as a way of checking the boiler.

Paperwork for a Cheshire quote

The first towns are Crewe, Nantwich and Sandbach. Anyone in the UK can still post a job or register a business [QZ5]. Up to five matched local businesses can send quotes [QZ2]. QuoteZila is free for customers and local businesses [QZ1].

Honest status: QuoteZila is new. We're starting in Cheshire, beginning with Crewe, Nantwich and Sandbach, and growing area by area. Anyone in the UK can still post a job or register a business. How fast you get quotes depends on how many local businesses have joined near you. Businesses can register and receive jobs straight away. We don't check insurance, qualifications or registrations, so please check these yourself before you hire.

Posting a job is not open yet

Heating engineers and plumbers are the live trade pages. Plumber cost and electrician cost in Cheshire are there when the quote spills into those trades.

This page is general information, not professional or legal advice. QuoteZila does not check Gas Safe, WaterSafe, NFRC, NICEIC or other registrations against the register on your behalf: look them up yourself.

Jobs you might post

These are examples, not taken from real job posts.

  • "Replace one radiator in a Crewe bedroom. Please quote a type 21 and write the height, length, output and pipe centres, and say if building regulations apply."
  • "Add a radiator in a Nantwich loft room that already has pipes. Competent person or building control, written in the quote. Do not ask me to drain anything."
  • "Sandbach living room. Old radiator leaking at a valve. Gas boiler in a cupboard. If you need to touch the boiler, say that you are Gas Safe registered for that appliance."

Questions about type 21 radiators

What is a type 21 radiator?

A type 21 radiator is a double panel with one set of fins. The BEIS heat-distribution report describes those fins as convection fins, welded on to move air, and it says double-panel radiators vary because some have two convectors and others only one. Ask the supplier to write the height, the length, the pipe centres and the heat output they are using for the room. If they cannot write those down, you do not yet have a quote you can compare.

Does adding a radiator need building regulations approval?

GOV.UK says you might need building regulations approval to add extra radiators to a heating system, and that you could need approval for works that are not on its list, so check the project. The same page says you do not need to get approval yourself if you use someone registered with a competent person scheme. A separate booklet lists addition of a radiator to an existing system as something you may need to tell a building control body about, and it notes that some circumstances may differ.

What if the boiler has to be opened?

Anyone employed to work on a gas appliance in a home must be a Gas Safe registered engineer, competent for that work, with the competencies shown on the ID card. Check them on the Gas Safe Register. Fitting a radiator on existing pipes is not, by itself, the same job as opening the boiler. If the visit includes the boiler, the flue or the gas pipework, use a registered engineer. Do not drain the system yourself.

What should the quote show?

Citizens Advice wants a written fixed price rather than a verbal guess, from at least three traders where you can get them, and a clear answer on VAT. GOV.UK says a business must register for VAT when taxable turnover for the last 12 months goes over £90,000. Ask who is moving the old radiator out of the house. A missing waste line is a different job, not a discount.

Does QuoteZila check the businesses?

No. We don't check insurance, qualifications or registrations, so please check these yourself before you hire. You can report a quote or a business from your job page.

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Sources

  1. QZ1: QuoteZila product fact. QuoteZila public pricing line.
  2. QZ2: QuoteZila product fact. QuoteZila terms, customers.
  3. QZ5: QuoteZila product fact. QuoteZila coverage wording.
  4. S1: Building regulations approval, GOV.UK. Accessed 2026-10-25. https://www.gov.uk/building-regulations-approval
  5. S2: Building work, replacements and repairs to your home, GOV.UK. Accessed 2026-10-25. https://www.gov.uk/government/publications/building-work-replacements-and-repairs-to-your-home/building-work-replacements-and-repairs-to-your-home
  6. S3: Domestic gas FAQ, HSE. Accessed 2026-10-25. https://www.hse.gov.uk/gas/domestic/faqs.htm
  7. S4: Before you get work done on your home, Citizens Advice. Accessed 2026-10-25. https://www.citizensadvice.org.uk/consumer/getting-home-improvements-done/before-you-get-building-work-done/
  8. S5: Register for VAT, GOV.UK. Accessed 2026-10-25. https://www.gov.uk/register-for-vat
  9. S6: Domestic heat distribution systems: evidence gathering, final report (BEIS research paper 2021/015, February 2021), Department for Business, Energy and Industrial Strategy, GOV.UK. Accessed 2026-10-27. https://assets.publishing.service.gov.uk/media/606c39c38fa8f515b4067b08/beis-dhds-final-report__1_.pdf