Hot Water Cylinder Replacement in Ireland:
What to Know Before You Buy
Last updated: May 2026
Your hot water cylinder running out faster than it used to? Seeing rust-coloured water, hearing strange noises from the tank, or just staring at an ancient copper cylinder that's been in the attic since the 1990s? Here's everything you need to know about getting it replaced, the right way.
A hot water cylinder replacement in Ireland costs €800–€1,800 supply and fit. The job takes 3–6 hours. For Kildare homes, a stainless steel cylinder is strongly recommended over copper, it handles hard water far better and lasts twice as long.
Signs You Need a New Hot Water Cylinder
Cylinders don't usually fail overnight, they degrade over time. Watch for these warning signs:
- Running out of hot water faster than before, internal corrosion reduces effective capacity
- Rust-coloured or discoloured water, a sign the cylinder is corroding from the inside
- Visible corrosion, damp or rust stains on or around the cylinder
- Long heat-up times, the immersion element or coil may be failing
- Age over 20–25 years, copper cylinders have a finite lifespan, especially in hard water areas
- Persistent dripping from the cylinder body or overflow pipe
Types of Hot Water Cylinder in Irish Homes
Vented (Gravity-Fed) Cylinders
The most common type in older Irish homes. A vented system works from a cold water storage tank (usually in the attic), relying on gravity for water pressure. The cylinder is "open" to the atmosphere through a vent pipe, hence "vented."
Advantages: simpler system, no complex pressurisation components, lower installation cost, easy to maintain.
Disadvantages: water pressure depends on tank height, ground floor showers often have poor pressure without a pump.
Unvented (Pressurised) Cylinders
Unvented cylinders connect directly to the mains water supply, delivering higher, more consistent pressure throughout the home. They're increasingly common in newer Irish builds.
Important note: Unvented cylinders must be installed by a G3-qualified engineer. The Pipe Guy installs vented cylinders only. If you need an unvented system, we'll point you to the right professional.
Copper vs Stainless Steel, Which Should You Choose?
| Copper Cylinder | Stainless Steel Cylinder | |
|---|---|---|
| Lifespan | 15–25 years | 25–40 years |
| Hard water performance | ⚠️ Susceptible to limescale | ✓ Excellent |
| Supply cost (150L) | €250–€450 | €450–€750 |
| Insulation | Lagged separately | Factory-fitted foam insulation |
| Best for Kildare? | ⚠️ Not ideal (hard water area) | ✅ Strongly recommended |
For homes in County Kildare, a hard water area, a stainless steel cylinder is strongly recommended. The higher upfront cost is offset by the significantly longer lifespan and lower maintenance in hard water conditions.
What Size Cylinder Do You Need?
Cylinder sizing depends on the number of people in the home and usage patterns. These are general guidelines:
- 1–2 people: 120–150 litres
- 3–4 people: 150–210 litres
- 5+ people or high demand: 250–300 litres
Your plumber will also consider your heat source (oil, heat pump, solar coil), recovery time and usage patterns before recommending a size. Going too small means running out of hot water; too large means you're heating more water than you need.
How Much Does a Cylinder Replacement Cost in Ireland?
| Cylinder Type | Supply & Install Cost | Labour Only |
|---|---|---|
| Copper vented (120–150L) | €800–€1,100 | €350–€550 |
| Copper vented (150–210L) | €900–€1,300 | €350–€550 |
| Stainless steel (150–210L) | €1,100–€1,600 | €350–€550 |
| Stainless steel (250–300L) | €1,400–€2,000 | €450–€650 |
Prices include VAT at 13.5%. Difficult access (cramped attic, awkward hot press) can increase labour costs. Always get a fixed-price quote before committing.
What the Job Involves
A cylinder replacement is a half-day job for an experienced plumber. Here's what typically happens:
- Turn off the water supply and immersion heater
- Drain the existing cylinder, either via the drain cock or hosepipe from the cold feed
- Disconnect all pipework, cold feed, hot draw-off, vent pipe, immersion element, and coil connections
- Remove the old cylinder, attic access can be the trickiest part of this job
- Position and connect the new cylinder, pipe connections, immersion element, coil
- Refill and check for leaks
- Commission and test, run the immersion, check temperature, verify all connections are tight
Cylinder Replacement and the Kildare Hard Water Problem
County Kildare has some of the hardest water in Ireland, with calcium hardness levels frequently above 300 mg/L. This accelerates limescale build-up inside copper cylinders and on immersion elements, one of the key reasons cylinders in Kildare tend to fail earlier than in soft water areas.
If you're replacing a copper cylinder that's failed prematurely, it's worth considering two things simultaneously: upgrading to stainless steel, and installing a water softener. Together, these two changes will significantly extend the life of your new cylinder and protect the rest of your plumbing system at the same time.