Service bank, reserve bank, pigtails and changeover equipment
Trace the whole LPG supply before blaming the changeover valve
An automatic changeover can keep a correctly arranged cylinder supply running when the service bank is exhausted. If supply stops, pressure falls, the indicator seems wrong or only one bank works, the fault may sit in the cylinders, valves, pigtails, changeover, regulator, demand, pipework or connected appliance.
The direct answer
A changeover is one controlled handover inside a complete supply system
Liquid Gas UK describes an automatic device between two cylinder banks: a service bank supplies first and a reserve bank takes over when the service side is exhausted. The device indicates that changeover, then the empty side is replaced and the service/reserve arrangement is restored. That sequence depends on a correctly selected, installed, commissioned and operated system.
Which cylinders are meant to supply now?
Record the number, fuel, size, supplier, valve position and connections on the selected side without altering them. "They look full" is not a reliable contents or flow check.
What device controls the handover?
Photograph the whole assembly, selector, indicator, data plate, mounting, weather protection and any OPSO or other safety-device markings. Do not open, adjust or force it.
Can the reserve side support the real demand?
Record the same details for the reserve side and list every connected appliance. Cylinder capacity, vaporisation, regulator flow and simultaneous heat input must work as one design.
This is not another regulator-age guide. For manufacture date, service life and replacement questions, use the separate LPG regulator replacement guide. This page focuses on cylinder-bank operation, supply failure and inspection evidence.
Common symptom groups
One symptom can have several supply-side and appliance-side causes
The reserve side does not take over
The reserve cylinder may be empty, closed, wrongly connected or unable to deliver enough vapour. A pigtail, non-return device, selector, regulator, safety device, pipe or the changeover mechanism may also be involved. The symptom does not name the failed part.
The fault follows a bank or connection
Record which side, which cylinders and what changed before the failure. Do not swap pigtails, connectors or regulator parts to prove a theory; doing so can introduce a leak, wrong component or unsafe reset state.
Status is mistaken for contents or safety
An indicator shows the state designed by its manufacturer. It does not universally measure cylinder contents, prove gas tightness or confirm correct outlet pressure. Supply photographs and the model instructions so its meaning can be checked.
The system cannot meet simultaneous demand
The connected load may exceed regulator flow, available cylinder vaporisation or pipework capacity under the current temperature and fill level. Frost can be an observation in that diagnosis, not proof that the changeover head alone is defective.
Manual and automatic are different booking facts
Name the control type before asking for a repair or replacement
Do not infer operation from colour or shape alone
A manual selector requires a documented user action to move to the alternate supply. An automatic device is designed to transfer supply when its switching condition is reached, but it still relies on the correct service and reserve sides, open and compatible cylinders, suitable pigtails, correct pressure regulation and a safe reset or restoration procedure.
Indicator colours and selector positions can be product-specific. Photograph the label and obtain the current instructions for that exact model. Do not publish or follow a generic "turn it this way" rule for an unidentified installation.
Telemetry can report status or help a supplier schedule cylinder replacement, but Liquid Gas UK's Code of Practice 33 says monitoring is not a safety device in its own right. A notification does not replace physical inspection, pressure checks, tightness work or safe commissioning where those are required.
Look beyond the changeover head
Pigtails, connections, mounting and protection can decide whether the bank works safely
Every cylinder-to-device path matters
Record each pigtail or hose, connector, cylinder valve and manifold component. Liquid Gas UK guidance for relevant commercial and event arrangements addresses non-return and excess-flow protection, hose routing and safe cylinder-changing arrangements.
The assembly must follow its design instructions
Photograph mounting height, support, enclosure, ventilation, water exposure, contamination, impact risk and the route from cylinder outlets. Do not reposition the assembly to improve a photograph or temporarily restore flow.
Fuel, pressure, flow and connections must match
The data plate should identify relevant gas and pressure information. Send cylinder brand and type, appliance data and every marking rather than asking an engineer to arrive with a generic "LPG changeover".
Not every visible component belongs to the customer
Check the LPG supply agreement. Some cylinder, pigtail, changeover or telemetry equipment may be installed and maintained by the supplier, while service pipework or downstream equipment may belong to the property or site owner.
Flow problems can imitate component failure
Declare the full load and the conditions when pressure falls
A cylinder can contain LPG and still fail to sustain the required vapour rate
LPG must vaporise inside the cylinder before vapour-fed equipment can use it. Available vaporisation changes with cylinder size, fuel level, ambient temperature and withdrawal rate. A system that runs one appliance may struggle when heating, hot water, cooking or commercial equipment operate together.
The regulator and changeover also have rated flow and pressure characteristics. Liquid Gas UK guidance requires regulators to suit the installed appliances when operating simultaneously. Pipe sizing, restrictions and appliance demand can create similar symptoms, so changing a head without calculating and testing the complete route may not solve the problem.
Record the time, weather, cylinder level or exchange date, appliances operating, how long the system had run, visible frost, indicator state and whether supply returned after demand fell. Do not warm a cylinder, lay it down or improvise extra banks.
Safety controls are not fault-finding buttons
Do not repeatedly reset, bypass or adjust an unidentified device
Over-pressure shut-off, under-pressure shut-off, excess-flow, non-return and relief arrangements have different purposes. HSE notes that an OPSO trip indicates an over-pressure condition and says the device is to be reset only by the gas supplier in the bulk-installation context it describes. Other products can have their own authorised procedures.
If the supply is off, first establish the device, ownership and manufacturer's instructions. Repeated resets, pressure adjustment, bypassing, uncapping or substituting parts can conceal the cause or defeat protection. A competent person should decide the investigation and restoration route for the real installation.
A shut-down system is not automatically safe to restart. Ask what caused the trip, what was tested, what was repaired and what commissioning evidence supports restoration.
Prepare a routable enquiry
Send both cylinder banks, the data plate and connected demand first
"The changeover is broken" does not reveal whether the job concerns a domestic four-cylinder bank, static caravan, park home, catering unit, rural commercial site, supplier-owned equipment, manual selector, automatic device, pressure fault or appliance issue. The details below help identify the right LPG category before attendance is promised.
Agree the attendance scope
Diagnosis, replacement, testing and certification are separate promises
Identify both banks and every control
Record fuel, cylinders, service/reserve selection, pigtails, changeover, regulator stages, protective devices, ownership boundary, pipework and connected equipment.
Inspect before condemning the head
Check accessible components, identification, mounting, deterioration, connections and the documented changeover operation. State anything inaccessible, supplier-owned or outside scope.
Select tests for the installation
The competent person decides the safe procedure and applicable current standard. A functional changeover observation is not automatically a complete tightness test, regulator test or appliance inspection.
Separate cause, defect and recommendation
Ask for observations, measured results where appropriate, unsafe action, fault diagnosis, parts required, ownership referral, repair completed, retest or commissioning need, limitations and whether normal use was restored.
Smell, hissing, damaged pigtail or uncontrolled release
Do not wait for a routine changeover appointment
Keep people away from danger, avoid flames and electrical switches where this can be done safely, and follow the LPG supplier's displayed emergency instructions. If there is fire, an uncontrolled release, immediate danger or doubt, evacuate and call 999.
Do not move cylinders, disconnect pigtails, turn an unidentified control, use a flame to search for a leak or repeatedly restore supply. Only shut off an accessible user emergency control when you already know its safe operating procedure and can do so without entering danger.
Upkeepone's normal enquiry numbers are not an emergency reporting service.
Match competence and ownership
The right route depends on the site, equipment and proposed work
Where the Gas Safety (Installation and Use) Regulations apply, use a Gas Safe registered business and verify the attending engineer's current ID-card categories for LPG, the premises and the work. A person qualified for one appliance or setting is not automatically qualified for every cylinder-bank, caravan, catering, commercial or industrial installation.
Check the supply contract before authorising work on supplier equipment. Large or specialist commercial banks, unusual pressures, event installations and process plant can require a different competent-person or responsible-engineer route. Ask the provider to confirm competence, scope, applicable instructions and ownership before shutdown or replacement is arranged.
Continue with the closest route
Choose changeover diagnosis, regulator age, testing or certification deliberately
Primary UK sources
Check current cylinder, changeover and competence guidance at source
Liquid Gas UK: Code of Practice 24 Part 3Public professional guidance for pressure regulators and automatic changeover devices in commercial catering and outdoor event settings.
Calor: cylinder storage and automatic changeoverSupplier explanation of cylinder sets, automatic transfer and the need for an LPG Gas Safe engineer for the initial fixed installation.
Calor: fixed-cylinder regulators and OPSOSupplier guidance on data plates, equipment ownership and contacting an LPG-qualified Gas Safe engineer.
HSE: LPG valves and emergency controlsThe purposes of pressure regulation, shut-off devices and the emergency control valve in the installation types HSE describes.
HSE: check Gas Safe registrationVerify the business, engineer identity and qualifications for the proposed gas work.
LPG cylinder-bank enquiries
Send the postcode before attendance is assumed
Regular work covers London, Essex and Kent. Hertfordshire, Surrey, Buckinghamshire, Berkshire and Sussex can be considered when the right LPG trade is available. Other UK areas are considered by request after the installation, supplier boundary, fault, required output and competence have been checked.
Check current feedback before sending the cylinder-bank details
Read Upkeepone's live Google results in their original context, then send the postcode, premises use, fuel, supplier, cylinder-bank layout, changeover data plate and indicator, pigtails, connected demand, fault history, photographs, access limits and required written output. Upkeepone can review the enquiry and check the relevant LPG competence route and current availability.
Cylinder-bank, indicator and booking questions
LPG changeover-valve FAQs
What does an automatic LPG changeover valve do?
Does an automatic changeover use both cylinder banks together?
Why has the LPG supply stopped when the reserve cylinders appear full?
Does the changeover indicator prove how much LPG remains?
Can I turn or reset the LPG changeover selector myself?
Are manual and automatic LPG changeover systems the same?
Does frost on a cylinder or regulator mean the changeover valve is faulty?
Do LPG pigtails and cylinder connections need separate checks?
Who can inspect or replace a fixed LPG changeover system?
What should I send before booking an LPG cylinder-bank inspection?
Need the fault assessed?
Send both banks, the data plate, symptom and connected load
Upkeepone can review the information supplied and check whether the proposed inspection or repair can be routed to an appropriate LPG trade. An enquiry does not confirm availability, price, ownership, compliance, diagnosis or that changeover work includes pipework, appliances, certification or every remedial item.
A current LPG smell, hissing, fire, uncontrolled release or damaged connection must use the supplier or emergency route above.
