Gas Appliance Servicing Beyond Boilers: Gas Fires, Hobs, Warm Air Units — Annual Check Scope and CP12 Coverage

Summary

Boilers dominate the domestic gas servicing market, but many properties contain other gas appliances that are equally capable of producing carbon monoxide, causing gas leaks, or causing fire. Gas fires are particularly concerning: they are often older, less well-maintained, and located in living rooms where occupants spend extended time — making CO from a faulty fire especially dangerous. A Gas Safe engineer servicing a property has both a professional and legal obligation to check all gas appliances present, not just the boiler.

The CP12 (Landlord Gas Safety Record) is commonly misunderstood as a "boiler certificate." It is not. The form specifically lists every gas appliance in the property, and the inspecting engineer must record the condition of each one. If an engineer issues a CP12 covering only the boiler while ignoring the gas fire in the living room, they are issuing an incomplete and potentially misleading safety record — a professional conduct issue and a liability risk.

For homeowners (as opposed to landlords), there is no legal obligation for an annual gas safety check, but manufacturers typically require evidence of annual servicing to maintain appliance warranty. The scope of a service visit should follow the manufacturer's instructions for each appliance type.

Key Facts

• Gas Safety (Installation and Use) Regulations 1998, Regulation 36 — landlords must ensure annual safety check by Gas Safe Registered engineer for all gas appliances
• CP12 — Landlord Gas Safety Record; must list every gas appliance; must be issued within 28 days of check
• Tenant entitlement — new tenants must receive CP12 before or at the start of tenancy; existing tenants within 28 days of each annual check
• Record retention — landlords must keep CP12 records for 2 years
• Gas Safe categories — engineers must be registered for the appliance type: CCN1 (central heating boilers), CENWAT (central heating/water heaters), HTR1 (space heaters/gas fires), CKR1 (cooking appliances), WAU (warm air units)
• Gas fire annual check — includes: visual condition, burner operation, flue/ventilation check, CO detector presence, flame picture and combustion performance
• Open-flued appliances — gas fires and some older boilers draw combustion air from the room; room ventilation adequacy is critical and must be checked
• Decorative fuel-effect (DFE) fires — must be inspected even if they appear rarely used; seal condition, burner, and flue
• Flueless gas fires — rare in permanent installations; must have ODS (Oxygen Depletion System) fitted; not permitted in rooms below 30m³
• Warm air unit (WAU) — central heating via ducted warm air; engineer must be WAU-registered; service includes heat exchanger inspection for cracks (critical CO risk)
• Gas hob/oven — annual check includes: igniter function, burner condition, gas soundness, flexible hose condition; hobs do not have flues (open room combustion) — room ventilation required
• Flexible hose condition — corrugated stainless steel hoses on cookers/hobs should be replaced every 5 years or when perished; check for kinks, damage, and correct WRAS-approved fittings

Quick Reference Table

Detailed Guidance

Gas Fires: Open-Flue and Balanced-Flue Types

Open-flued gas fires draw combustion air from the room and exhaust to a chimney flue. Annual service must include:

• Spillage test — hold a smoke match or tapered smoke pellet at the draught diverter with the fire on; no smoke spillage into the room is acceptable. If spillage occurs, the fire must be turned off and not used until the flue is investigated.
• Chimney pull test — check adequate draw exists; a minimum of 12 Pa negative pressure in the flue is required for most open-flued appliances (check appliance manual)
• Room ventilation — calculate whether the room has adequate ventilation for the appliance's heat input; for fires over 7kW, 5cm² of ventilation per kW above 7kW is required
• ODS (Oxygen Depletion System) — check ODS pilot is functioning; ODS shuts the fire down if room oxygen falls below a critical level
• Burner and injector condition — inspect for blockage, corrosion, and correct flame picture (blue flame with defined cone; yellow-tipping or orange flames indicate incomplete combustion)
• CO detector — advise the occupant that a CO detector should be fitted in every room with a gas appliance; confirm one is present in the room with the fire

Balanced-flue gas fires draw combustion air through the outer annulus of a concentric flue and exhaust through the inner. They are sealed from the room and generally safer from CO spillage. Annual check includes:

• Terminal condition — check the external terminal is clear and undamaged
• Combustion performance
• Controls and thermostat function

Decorative Fuel-Effect (DFE) Fires

DFE fires simulate a coal or log fire effect but burn real gas. Many are open-flued and fitted to traditional fireplaces. They are a known high-risk appliance type because:

• They are often installed in old, poorly-maintained chimneys
• Owners use them infrequently, meaning deterioration goes unnoticed
• Flue liners may not have been fitted when the fire was installed
• The flickering "fuel effect" flame makes combustion assessment more difficult

Annual check protocol:

• Spillage test (critical — many DFE fires have poor spillage performance in old chimneys)
• Sweep chimney if not swept in current year
• Check liner condition if accessible
• Confirm ember fuel bed is not restricting combustion air
• Advise homeowner/tenant on cleaning frequency for the fuel bed

Action on failed spillage test: if an open-flued appliance (gas fire or DFE fire) fails a spillage test, it must be labelled as IMMEDIATELY DANGEROUS (ID) and disconnected. The CP12 must record this action. Do not leave the appliance connected and hope the occupant doesn't use it.

Warm Air Units (WAUs)

Warm air units are less common than radiator-based central heating but still found in properties built primarily in the 1960s–1980s. The unit typically consists of:

• A gas burner and heat exchanger (draws flue gases away)
• A fan blowing over the heat exchanger to distribute warm air
• Ductwork to each room

The critical safety concern with WAUs is heat exchanger integrity. A cracked heat exchanger allows combustion gases (including CO) to mix with the warm air circulating through the building — this is a severe CO risk and has caused fatalities. Annual service must include:

• Visual inspection of heat exchanger for cracks, holes, or corrosion
• Smoke or CO tracer test where cracks are suspected
• Flue condition and draught
• Burner condition and combustion analysis
• Pilot and thermocouple condition
• Duct condition (no obstructions, bends in good condition)

A WAU with a cracked heat exchanger must be condemned (IMMEDIATELY DANGEROUS) and disconnected immediately.

Gas Hobs and Ovens

Hobs and ovens combust gas in the room (open combustion) and do not have flues. Room ventilation requirements under Building Regulations Part J:

• Kitchen must have at least 0.5× room volume per hour air exchange rate
• Extraction canopies and mechanical ventilation do not satisfy the combustion air requirement — permanent ventilation is required

Annual check scope:

• Flexible hose condition — check for kinks, perishing, WRAS/BS-approved fittings; replace if over 5 years old or showing wear
• Ignition — test all burners ignite promptly; check igniter electrode condition
• Burner caps — check caps are seated correctly and clear of food debris (blocked burners affect combustion)
• Oven thermostat — check oven reaches and maintains set temperature
• Gas soundness — test with soap solution or electronic gas detector around all connections
• Stability chain — freestanding cookers must be secured to the wall with an anti-tilt bracket

Completing the CP12 Correctly

The CP12 form has sections for each appliance. For each one, the engineer must record:

• Appliance type and location
• Appliance manufacturer and model (where visible)
• Whether appliance is safe/unsafe/at risk
• Any defects noted
• Actions taken (e.g., disconnected, advisory issued)

If any appliance is found to be IMMEDIATELY DANGEROUS (ID) — meaning it presents an immediate risk to life — it must be disconnected if the owner/occupant consents. The situation is documented on the CP12 with a Gas Safe warning label attached to the appliance.

If the occupant refuses disconnection, note the refusal in writing and on the CP12. Contact Gas Safe Register for guidance on reporting if you believe the occupant is at risk.

Frequently Asked Questions

Do I need different Gas Safe categories to service all appliances on a CP12?

Yes. An engineer registered only for CCN1 (central heating boilers) cannot legally service a warm air unit (WAU registration required) or a cooking appliance (CKR1). Before taking on a landlord safety check contract, confirm you hold the categories for every appliance type in the property. If you don't, sub-contract the additional appliances to an engineer who does or arrange for the missing appliances to be checked by a specialist.

Can a gas fire be condemned at annual service even if it's working?

Yes. "Working" and "safe" are different things. A gas fire may ignite and produce heat while simultaneously spilling combustion gases into the room. Spillage test results, CO readings, and flue condition determine safety — not whether the appliance lights. An appliance that fails a spillage test is immediately dangerous regardless of its operation.

What is the difference between ID (Immediately Dangerous) and AR (At Risk)?

• ID (Immediately Dangerous) — presents an immediate risk to life; must be disconnected if consent given
• AR (At Risk) — does not meet safety requirements but does not pose an immediate risk; occupant must be warned and the situation documented; the appliance should not be used until repaired
• NCS (Not to Current Standards) — older installation that does not comply with current standards but is not classified as dangerous; record and advise

These classifications are from the Gas Industry Unsafe Situations Procedure (GIUSP), which all Gas Safe engineers must follow.

Does a homeowner (not a landlord) need all their gas appliances checked annually?

Not legally, but it is strongly recommended. The HSE and Gas Safe Register both advise annual safety checks for all gas appliances in owner-occupied homes. For the engineer, the professional obligation to report and document unsafe conditions applies regardless of tenure — if you find an immediately dangerous appliance in a homeowner's property, the same duty of care applies.

Regulations & Standards

• Gas Safety (Installation and Use) Regulations 1998 — Regulation 36: landlord obligations; Regulation 26: installation and maintenance competency

• Gas Industry Unsafe Situations Procedure (GIUSP) — classification of ID/AR/NCS and engineer obligations

• Building Regulations Part J — combustion appliances; ventilation requirements for gas fires, hobs, and warm air units

• BS 6896 — Installation of gas-fired ducted air heaters (warm air units)

• BS 5871 — Installation and maintenance of gas fires; Parts 1–4 cover different fire types

• IGEM/UP/10 — Installation of gas appliances in industrial and commercial premises

• Gas Safe Register — registration categories, CP12 guidance, and landlord obligations

• HSE Gas Safety — landlord gas safety requirements and GIUSP guidance

• CORGI HomePlan Technical Guidance — practical servicing guidance

• Carbon Monoxide Be Alarmed — CO safety information for gas engineers

• natural gas vs lpg — LPG appliance servicing requirements

• boiler selection — boiler types and annual service requirements

• gas safety — Gas Safe registration and compliance overview

• fire safety site — carbon monoxide risks and detection