Hot Water Cylinder Plumbing in Essex

Hot water cylinder work Rez can help with

Typical work can include:

• Vented hot water cylinder plumbing
• G3 unvented cylinder plumbing
• Cylinder fault investigation
• Annual unvented cylinder servicing
• Immersion thermostat replacement
• Expansion vessel checks and replacement
• Safety-valve and control faults
• Tundish discharge investigation
• Leaking cylinder connections
• Associated hot and cold pipework
• Cylinder replacement
• Advice on suitable replacement options

The right approach depends on the cylinder type, system arrangement, fault and condition of the existing installation.

Is your cylinder vented or unvented?

A vented cylinder is normally supplied from a cold water storage tank in the loft. Hot-water flow is produced by gravity, so performance depends on tank height, pipe size and the system layout.

An unvented cylinder is supplied directly from the incoming mains and provides pressurised hot water. It includes pressure, temperature and expansion controls that must operate correctly.

Typical signs of a vented system include:

• A cold water storage tank in the loft
• Lower hot-water pressure than the cold mains
• An open vent pipe above the storage tank
• A traditional copper cylinder in an airing cupboard

Typical signs of an unvented system include:

• Strong mains-pressure hot water
• An expansion vessel or internal expansion arrangement
• A tundish and discharge pipe
• Pressure-reducing and safety controls
• A cylinder label identifying it as unvented

Send a clear photograph of the whole cylinder and its label if you are unsure which system you have.

Common hot water cylinder problems

Customers commonly enquire about:

• No hot water
• Water not staying hot
• A leaking cylinder or connection
• Water passing through the tundish
• An external discharge pipe dripping
• Loss of hot-water pressure
• Noisy operation
• A failed thermostat or immersion heater
• An expansion vessel losing charge
• Overflowing cold water storage tanks
• Corroded or poorly arranged pipework

The visible symptom does not always identify the failed component. For example, water through an unvented-cylinder tundish can be caused by expansion, pressure or a safety-control fault.

The system should be assessed before parts are replaced unnecessarily.

Unvented cylinders and G3 safety controls

Unvented cylinders contain safety devices designed to control pressure, temperature and expansion.

These may include:

• Pressure-reducing valves
• Expansion relief valves
• Temperature and pressure relief valves
• Expansion vessels
• Thermostats
• High-limit safety cut-outs
• Tundish and discharge pipework

Water passing through the tundish is a warning that a control or safety valve may be operating. It should not be ignored, capped or altered simply to stop the visible discharge.

Work involving the installation or safety controls of an unvented cylinder must be handled by someone with the appropriate G3 qualification.

REZ Heating & Plumbing Services is G3 Unvented qualified.

Expansion vessels and pressure problems

Water expands as it heats. An unvented system needs a safe way to absorb that expansion.

If an external expansion vessel loses its air charge or the internal diaphragm fails, pressure can rise and water may discharge through a safety valve.

Possible signs include:

• Water passing through the tundish during heating
• Pressure rising as the cylinder heats
• Repeated relief-valve discharge
• A vessel that sounds completely full of water
• Discharge stopping temporarily after the system cools

An expansion vessel may sometimes be recharged. It requires replacement when the diaphragm has failed or the vessel is otherwise defective.

Recharging the vessel without checking the wider cause may not provide a lasting repair.

Vented cylinders and gravity hot water

A vented cylinder normally forms part of a system that also includes a loft storage tank.

Poor hot-water flow may be caused by:

• Low storage-tank height
• Restricted pipework
• Air locks
• Partially closed valves
• Poorly arranged cylinder connections
• A storage tank that is not filling correctly
• An undersized or unsuitable system
• Problems with an existing shower pump

The cylinder itself should not automatically be blamed for low pressure.

Where stronger shower performance is required, a suitable shower pump may be possible, but the cold water storage, cylinder connections and pipe routes need to be checked first.

Immersion heaters and thermostats

Many cylinders use an immersion heater as the main source of hot water or as a backup.

Common symptoms include:

• No hot water from the immersion
• Water becoming excessively hot
• The safety cut-out repeatedly tripping
• Intermittent heating
• Only the boost supply working
• An Economy 7 off-peak supply not heating the cylinder

A failed thermostat or immersion heater may be replaceable.

However, if the electrical supply is missing or faulty before it reaches the cylinder controls, an electrician or electricity supplier may need to investigate the upstream electrical fault.

REZ can assess the cylinder and water-side controls but will not conceal an electrical supply problem by replacing working plumbing components.

Why water may be passing through the tundish

A tundish provides a visible indication that water is being discharged from an unvented cylinder safety or control valve.

Possible causes include:

• Expansion vessel pressure loss
• Internal expansion needing reinstatement
• A faulty pressure-reducing valve
• An expansion relief valve fault
• Excessive incoming pressure
• Overheating
• A valve that has opened and failed to reseat
• Incorrect installation or discharge arrangements

The cause should be diagnosed rather than assuming the tundish or discharge pipe itself is faulty.

Do not block or cap the discharge.

Repair or replace the cylinder?

Repair is often sensible when:

• The cylinder body remains sound
• The fault is limited to a thermostat or control
• A valve, vessel or connection has failed
• Suitable replacement components are available
• The installation remains appropriate for the property

Replacement may be more practical when:

• The cylinder body is leaking
• Significant corrosion is present
• Several components are failing
• The cylinder is unsuitable for the household demand
• The installation is inaccessible or poorly arranged
• Replacement parts are obsolete
• Previous repairs have not provided a reliable result

A leaking connection can often be repaired. A leak from the cylinder body normally means the cylinder requires replacement.

What happens during an unvented cylinder service?

The checks depend on the cylinder model and installation, but a service may include:

• Visual inspection of the cylinder
• Checking for leaks or corrosion
• Checking expansion provision
• Checking the expansion vessel where fitted
• Operating relevant safety valves
• Inspecting the tundish
• Reviewing the discharge arrangement
• Checking thermostatic controls
• Checking visible pressure-control components
• Identifying obvious installation concerns

Servicing cannot guarantee that a component will never fail, but it can identify visible faults and help maintain correct operation.

The manufacturer’s instructions should be considered for the specific cylinder.

Cylinder replacement and access

Replacing a hot water cylinder normally involves more than disconnecting two pipes.

The quotation may be affected by:

• Cylinder size and capacity
• Airing-cupboard access
• Doorway and stair access
• Existing pipe positions
• Number and condition of controls
• Discharge pipework
• Immersion-heater arrangement
• Secondary-return connections
• Whether the cylinder can be drained normally
• Removal of the old cylinder
• Changes required to surrounding pipework

Before choosing a replacement, the existing cylinder label, dimensions and system arrangement should be recorded.

A replacement should be selected for the property and demand rather than solely by matching the cylinder height.

What photos help with an assessment?

Useful photographs include:

• The whole cylinder
• The cylinder manufacturer’s label
• The top and bottom connections
• The tundish
• Any visible discharge
• The expansion vessel
• Valves and controls
• Immersion-heater covers
• Surrounding cupboard access
• The cold water storage tank for a vented system
• Any error display or electrical timer
• The external discharge pipe if water is visible outside

Please also send:

• The property postcode
• Whether there is any hot water
• Whether the fault is constant or intermittent
• Whether water is passing through the tundish
• Whether boost or off-peak heating works
• When the cylinder was last serviced
• Any recent plumbing or electrical work

Clear photos can help identify the cylinder type and determine whether a visit, service or specialist part may be required.

FAQs

Frequently asked hot water cylinder questions