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Plumbing

Water tanks and cylinders

Replacing an attic tank or a hot water cylinder, including insulated units.
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Whether this needs a licence in Ireland

Ireland

No licence required

Taken from the statute below; not yet reviewed by a lawyer

Irelandwww.cru.ieChecked

Water tanks and cylinders: what the job involves

Replacing the cold-water storage tank in the attic or the hot water cylinder in the hot press, or its immersion element. Old galvanised tanks rust through and copper cylinders wear out; a new insulated unit also cuts heat loss.

Also asked for as: hot water cylinder replacement · immersion not working · attic water tank · hot press cylinder · immersion element

How the job is usually done

  1. Identify what is there: tank material and size, vented or unvented cylinder, coil for the boiler, immersion.
  2. Check access: the attic hatch and floor for a tank, the hot press door for a cylinder.
  3. Turn off the boiler and immersion, isolate the water and drain down.
  4. Disconnect and remove the old tank or cylinder.
  5. Fit the new unit on a sound base, reconnecting feed, vent, overflow and boiler flow and return.
  6. Refill, bleed air, check for leaks and set the cylinder thermostat.
  7. Fit the tank lid, insulation jacket and insulate the pipes in the attic.

Water tanks and cylinders: what is included

Usually included

  • Removal of the old tank or cylinder
  • Fitting and reconnecting the new unit and valves
  • Insulation and a fitted lid for a new attic tank
  • Leak testing and setting the thermostat

Usually not included — agree it separately

  • Electrical connection of a new immersion or a new circuit, which an electrician does
  • Boiler work, which needs a Registered Gas Installer on a gas system
  • Disposal of an old cylinder, unless agreed — many plumbers take the copper
  • Converting the whole system to mains pressure

Materials and who supplies them

  • The new tank or cylinder: usually supplied by the plumber, who knows the size and connections needed
  • Valves, fittings and overflow pipe: supplied by the plumber
  • Immersion element and thermostat, if being replaced
  • Base boards for a new attic tank where the joists cannot take the load

How long it takes

Half a day to a day; longer if the cylinder will not fit through the hot press door or the boiler pipework has to be altered.

When to book

Do it before winter; an attic tank or exposed pipes in a cold attic are the first things to freeze.

Water tanks and cylinders: the rules in Ireland

What the official sources say, checked against them on the date shown. A summary, not legal advice — follow the link to read the rule itself.

  • Plumbing is not a restricted trade in Ireland: there is no statutory register of plumbers. The restricted works are electrical (Safe Electric) and gas (RGI), and they often sit next to plumbing.

    Applies to: the homeowner choosing a plumber

    Commission for Regulation of Utilities · cru.ie · Checked 9 October 2026

  • Any new circuit, for example to a new immersion or a heat pump cylinder, is Restricted Electrical Works and must be done and certified by a Registered Electrical Contractor.

    Applies to: the electrician on the job

    Safe Electric Ireland, under the Commission for Regulation of Utilities · safeelectric.ie · Checked 9 October 2026

  • Anything that touches a gas boiler, gas water heater or gas pipework may only be done by a Registered Gas Installer, who must leave a Declaration of Conformance.

    Applies to: anyone working on gas, and the homeowner who hires them

    Register of Gas Installers of Ireland, under the Commission for Regulation of Utilities · rgi.ie · Checked 9 October 2026

  • A VAT-registered plumber charges the reduced rate of 13.5% on work to a home, unless the materials come to more than two-thirds of the total, when the two-thirds rule puts the whole job at the rate of the goods.

    Applies to: VAT-registered contractors

    Revenue Commissioners · revenue.ie · Checked 9 October 2026

What water tanks and cylinders costs, and why

What jobs on Talqero came to

Not enough comparable jobs yet to publish a range here. Talqero shows a price range only once at least five comparable jobs, agreed prices or offers exist — a range from fewer would describe a handful of jobs, not the market. Post your job and compare the offers you get.

What affects the price

  • Tank or cylinder size and type: vented, unvented, direct or indirect, heat pump
  • Access through the attic hatch or hot press door
  • Pipework that has to be modified to match the new connections
  • A new immersion element, thermostat or controls
  • Draining down a system with radiators and inhibitor
  • VAT: building work on a home is charged at the reduced rate of 13.5% by a VAT-registered business — unless the materials come to more than two-thirds of the price, when Revenue’s two-thirds rule applies the goods rate to the whole job. Ask whether a quote includes VAT.

Paperwork to ask for at the end

  • Manufacturer guarantee for the cylinder or tank, registered in your name
  • For an unvented cylinder: a commissioning record showing the safety valves were set and tested
  • Safe Electric Completion Certificate if an electrician ran a new circuit

Safety

  • An unvented (mains pressure) cylinder stores hot water under pressure and relies on safety valves; it should be installed and serviced by someone trained on that system.
  • Stored hot water should reach 60°C regularly to control legionella; a thermostatic mixing valve stops scalding at the taps.
  • An attic tank holds a large weight of water: it must sit across joists on a proper base, never on the ceiling.

Water tanks and cylinders: before you hire

Questions to ask a tradesperson

  • Is a like-for-like cylinder the right choice, or should I plan for a heat pump?
  • Will the new tank have a lid, insulation and a screened overflow?
  • Does the price include taking the old one away?
  • Who connects the immersion?

What you can do yourself

Fitting an insulation jacket or lagging attic pipes is good DIY; draining down and replacing a tank or cylinder is not.

What to put in your task

  • What needs replacing?
  • What is happening?
  • How is your water heated?
  • How do you get into the attic?

Photos that help

  • The cylinder in the hot press, showing the label and the pipes on top
  • The attic tank with its lid off, and the joists around it
  • The attic hatch opening
  • Any leak or rust marks

Water tanks and cylinders by county

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Questions about water tanks and cylinders

Does water tanks and cylinders need a licence in Ireland?

No licence is required for this work in Ireland (source: www.cru.ie). Ask instead for references and photographs of similar jobs.

How do I know if my attic tank needs replacing?

Rust on an old galvanised tank, a sagging plastic tank, or rusty water from the cold taps are signs. A tank with no lid lets debris and insects into the water.

Should I replace my cylinder if I am getting a heat pump?

Usually the heat pump installer fits a new cylinder sized for the heat pump. If a heat pump is likely in the next few years, mention it before replacing the cylinder.

Why is my overflow pipe dripping outside?

Usually a float valve in the attic tank or the cistern is not shutting off. It is a small repair, but leave it and the tank can overflow into the attic.

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