Hot Water Cylinder Types Compared
There are a handful of cylinder types in Irish homes, and the right one depends on how your home is plumbed, the water pressure you want and whether a boiler or an immersion does the heating. Here is what sets each apart before you get a quote.
Vented copper
The traditional Irish cylinder, fed from a cold tank in the attic and sitting in the hot press. It is heated by the boiler coil, an immersion element, or both, and delivers hot water at gravity pressure. In most older homes it is a straightforward like-for-like swap.
Unvented pressurised
Fed straight from the mains with no attic tank, delivering hot water at mains pressure to every tap and shower. It needs a safe location for the discharge pipe and suits homes that want stronger, balanced pressure.
Direct and indirect
A direct cylinder is heated by one or two immersion elements only, with no boiler coil, which suits electric-only homes with no boiler feeding the hot water. An indirect cylinder is heated mainly by the boiler through an internal coil, with an immersion as backup, and is the usual choice where a boiler heats both the radiators and the hot water.
Twin-coil
A twin-coil cylinder has a second coil that can connect to a solar thermal panel later, so you can add solar water heating without replacing the cylinder again. It is a small upfront cost for a common long-term win, and it is also the shape a heat pump cylinder takes.
| Type | Best for | Heated by | From |
|---|---|---|---|
| Vented copper | Homes with an attic tank | Boiler coil or immersion | €600 |
| Unvented | Strong mains-pressure hot water | Boiler coil or immersion | €1,000 |
| Direct | Electric-only, no boiler | Immersion elements | €600 |
| Indirect | Boiler-heated homes | Boiler coil, immersion backup | €650 |
For prices and county coverage on any of these, see our hot water cylinder replacement guide.
Sizing a Cylinder to Your Household
The most common complaint after a cylinder swap is running short of hot water, and it almost always comes down to size. A cylinder that suited a two-person home years ago will struggle once there are teenagers and a second bathroom in the house.
Size to people and bathrooms
A good plumber sizes the cylinder to the number of people and bathrooms, and to how you use hot water, rather than simply matching the litre size of the old one. A slightly larger cylinder costs a little more up front but avoids the immersion running flat out to keep up.
Recovery time and insulation
Recovery time, how quickly the cylinder reheats after a draw, matters as much as raw litre capacity, and a well-insulated cylinder holds heat longer between draws. If your old cylinder always ran short, ask the plumber to size up rather than replace like-for-like.
- Size to people and bathrooms, not just the old cylinder
- Recovery time matters as much as raw litre capacity
- A well-insulated cylinder holds heat longer between draws
Vented vs Unvented: What Changes
A vented copper cylinder is fed from a cold tank in the attic and delivers hot water at gravity pressure, which is why upstairs showers can feel weak. An unvented pressurised cylinder does away with the attic tank and feeds from the mains, so every tap and shower runs at mains pressure.
What unvented needs
Unvented cylinders bring stronger, more balanced pressure, but they need a good incoming mains flow, expansion and safety controls, and a safe route for the discharge pipe. That is why they cost more to fit than a straight copper swap, and why the plumber will check your mains before recommending one.
Which suits your home
If your home has an attic tank and you are happy with the pressure, a like-for-like vented copper swap is usually the simplest and cheapest choice. If weak upstairs pressure is the problem and your mains flow is strong, moving to unvented is worth pricing. Ask the plumber to confirm your mains before you commit.
Heat Pump Cylinders
If you are moving to a heat pump, the cylinder question changes. Most existing cylinders are not compatible, because the standard vented copper cylinder is designed for the high flow temperatures of a gas or oil boiler. A heat pump runs cooler, so the coil inside the cylinder needs to be much larger to transfer the same heat.
What a heat pump cylinder is
A heat pump cylinder is an unvented pressurised unit with a large lower coil, typically 2.5 to 3 metres long, sized for 35 to 45 degree flow temperatures. It is larger than a standard cylinder, usually 200 to 300 litres, with an immersion heater as backup for cold spells.
Plan for solar with twin-coil
Many plumbers recommend a twin-coil cylinder here, so the second coil can connect to a solar thermal panel later without replacing the cylinder again. If a heat pump is on your horizon, see our heat pumps and your plumbing guide, and the SEAI grants explained page for what support is available.
What a Hot Water Cylinder Costs in 2026
A hot water cylinder replacement in Ireland costs €600 to €1,200 fitted for a copper cylinder in 2026, with labour and VAT included. A like-for-like copper swap sits at the low end, while an unvented pressurised cylinder sits at the top because of the extra controls and safe discharge it needs. Dublin and the commuter belt typically carry a 10 to 15 per cent premium over rural counties.
| Job | Typical cost | Notes |
|---|---|---|
| Copper cylinder, supply and fit | €600–1,200 | Like-for-like vented swap |
| Unvented pressurised cylinder | €1,000–2,000 | Adds controls and discharge |
| Indirect cylinder, supply and fit | €650–1,300 | Boiler coil plus immersion |
| Heat pump cylinder, supply and fit | €1,500–2,500 | 200 to 300L unvented |
| Immersion element replacement | €150–300 | Repair, not a full swap |
| Cylinder thermostat replacement | €80–150 | Common quick fix |
| Lagging jacket, supplied and fitted | €30–60 | Cuts standing heat loss |
These are indicative ranges only, so always confirm with a written quote. For more on prices across every job, see our plumbing costs guide.
Installation and Who Fits It
A hot water cylinder is standard plumbing and immersion work, so a competent plumber can carry it out. It is not gas work, so it does not need an RGI-registered gas installer unless a gas boiler is being altered at the same time. A like-for-like copper swap is usually a half-day to one-day job.
How the job runs
The plumber isolates and drains the old cylinder, disconnects it from the coil, immersion and pipework, and lifts it out of the hot press. The new cylinder is set in place and connected to the cold feed, hot draw-off, boiler coil where present and the immersion element. Controls and insulation are fitted, the system is refilled and checked for leaks, then the cylinder is heated and handed over.
Choosing a plumber
Get three written quotes, each naming the cylinder make, litre size, grade and labour, because a quote with no named cylinder is hard to compare. If you want an unvented cylinder, confirm the plumber has fitted unvented units before, as they involve mains-pressure safety controls. For a failed element only, remember an immersion element repair is far cheaper than a full swap.
Key takeaways
- A vented copper cylinder is fed from an attic tank at gravity pressure; an unvented pressurised cylinder feeds from the mains and gives strong pressure at every tap but needs safety controls and a good incoming flow.
- A twin-coil cylinder has a second coil so you can add solar thermal later without replacing the cylinder again.
- Size the cylinder to the number of people and bathrooms and how you use hot water, not simply to match the old one.
- A heat pump needs its own cylinder: an unvented unit with a large lower coil, usually 200 to 300 litres, sized for low flow temperatures.
- Fitted prices in 2026 start at €600 for a copper cylinder and €1,000 for an unvented pressurised cylinder.
