Appliance connections and isolation

The end of the pipework, where it meets each appliance, is where the installation is most often worked on: appliances are serviced, swapped and disconnected. This lesson covers the valves, test points and connections that make that safe.

Isolating each appliance

GSIUR requires a means of shutting off the gas at the inlet to every appliance you install, unless that isn't reasonably practicable (reg. 26(6)). Usually this is an appliance isolation valve: a manual valve that shuts off one appliance. On a cooker or tumble dryer it may be a self-sealing connector. BS 6891's pipework ends at the inlet of the isolation valve or self-sealing connector.

How appliances are connected

• Flued domestic appliances must be connected by a permanently fixed rigid pipe (GSIUR reg. 26(2)). The Unsafe Situations Procedure classes a flexible connection to a flued domestic appliance as At Risk; gas tumble dryers installed to BS 7624 are the exception.
• Self-sealing sockets for flexible connections must meet BS 669-1, BS 669-2 or BS EN 15069, and be installed to BS 6172 (cookers) or BS 7624 (tumble dryers).
• The hoses used as the final connection to movable appliances are covered by those appliance standards, not by BS 6891. Flexible hoses aren't allowed as part of the fixed pipework itself, except in a few LPG and park home situations.

Test points

• Fit a pressure test point for tightness testing. Where the meter installation doesn't include one, fit it no more than 300 mm downstream of the ECV or any AECV.
• Where the appliance doesn't have a suitable test point, fit one at its inlet. It can be built into the appliance isolation valve.

Position test points so they're easy to use for testing.

Additional emergency control valves

An AECV must be fitted where the ECV is remote from the building it serves, for example where the meter is outside and away from the building, or where a block of flats has its meters together away from the individual flats (BS 6891 Figure 10 shows typical layouts). Every AECV must:

• be as near as practicable to where the pipework enters the building
• be marked to show its open and closed positions
• be readily accessible (between 450 mm and 1450 mm above the floor is suggested) and easy to operate
• have a securely fixed handle or other permanent means of operation
• if its lever moves up and down, turn off by moving down.

A permanent notice on the valve must say it's an emergency control for the gas user, which parts of the installation it shuts off, the National Gas Emergency number, and what to do if they smell gas.

Outside appliances

Where pipework leaves a building to supply an appliance outside, such as a patio heater or barbecue, fit a valve in an accessible position where the pipe leaves the building, preferably outside.

Finishing the job

• If an appliance's heat input is range-rated or variable, permanently mark on the appliance the heat input it has been set to.
• Disconnect redundant pipework and remove it where practicable. Any left in place must be isolated and sealed at each end with an appropriate fitting.
• Pipework no longer needed is disconnected as close as practicable to where it joins the live supply, and any part that may still contain gas is labelled.

Sources: GSIUR 1998 reg. 26(2), (5), (6)isolation, connection BS 6891:2015 6.8, 9sockets, hoses BS 6891:2015 8.5–8.6AECVs, test points BS 6891:2015 8.3.10, 10.1, 11.2marking, redundant pipe IGEM/G/11 Ed. 2 Table 1situation 7.11 CCN1 Issue 16 §5, §9assessed

▸Tutor notes

• Give learners three layouts (internal meter in a house, external meter box on the house, meters in a ground-floor room of a block of flats) and ask where an AECV and test points are needed.
• Ask why a flexible connection to a flued boiler is At Risk but one to a freestanding cooker isn't.
• CCN1 §5 item 12 (requirements for AECVs) and §9 (positioning of emergency controls) are covered here.