Most hot water cylinders used to be made of copper and weren’t very well insulated, you could insulate them by covering with a red jacket that had insulation inside but they still tended to lose a lot of heat.
These are basically a storage facility for your hot water requirements. Choosing the right one for your home is important as you don’t want to spend out the money again because you chose the wrong size. You can either choose stainless steel or copper cylinders, there are a lot out there on the market so you have plenty of choice. A lot of them come with a 10 year guarantee from date of installation which is a good selling point when making your decision.
You will hear the term direct, in-direct, vented, unvented, so i’m going to go through the different types to clarify everything for you.
Vented cylinder
Vented hot water cylinders are fed from a tank in the loft. Every time you use hot water from the taps the cold water tank in the loft automatically fills the hot water cylinder. They are normally made of copper and the standard size is 210 litres the amount it takes to fill a bath.
They are only used for hot water so just have an outlet at the top of the hot water cylinder. There is also a larger hole to insert an immersion heater.
Unvented Cylinders
This type of cylinder has mains water directly running through it. Instead of a tank in the loft, mains water runs right into the bottom of the cylinder. The hot water comes out at the top as soon as hot water is drawn from any of the utilities. The good thing about this type of cylinder the water is mains pressure out the taps, very common in most modern homes
Indirect Cylinders
The water travels through the central heating pipes into the the hot water cylinder around a coil and the water that’s inside the tank gets heated up as the central heating water circulates. You normally have a programmer that has hot water only or central heating only, when you push the hot water button a valve by the cylinder switches the water so it travels through the cylinder instead of the radiators giving you hot water only. If you have the central heating button on at the same time another valve will open so the water circulates around the heating system also.
Hot Water Cylinders – Supply, Installation & Maintenance
Looking for a reliable, energy-efficient hot water solution for your home or business? We supply, install, and maintain vented and unvented hot water cylinders, ensuring powerful performance and long-term reliability. Whether you’re upgrading an old system or fitting a new build, our expert engineers are here to help.
Why Choose Our Hot Water Cylinder Services?
- ✅ Fully qualified, Gas Safe registered engineers
- ✅ Fast, professional installation
- ✅ 10-year warranties on selected models
- ✅ Emergency call-out service available
- ✅ Competitive pricing with no hidden charges
We only work with the most trusted brands on the market, including Megaflo, Gledhill, and Ariston, so you can be confident you’re getting top-quality equipment with expert workmanship to match.
Types of Hot Water Cylinders
Unvented Cylinders
Unvented systems are connected directly to your mains water supply, delivering high pressure hot water to multiple taps at the same time. Perfect for larger homes, modern bathrooms, and properties where water pressure matters.
Vented Cylinders
Vented systems are gravity-fed and typically used in older properties. While they offer lower pressure, they’re simple, cost-effective, and easy to maintain. If you’re replacing an existing vented cylinder, this might be the most straightforward option.
Not sure what’s right for your property? Speak to one of our specialists – we’ll guide you through the best system based on your home, usage, and budget.
Hot Water Cylinder Installation & Replacement
We offer a full end-to-end service for hot water cylinder installation, including:
- Removal and disposal of your old tank
- New pipework and fittings
- Pressure testing and safety checks
- Post-installation support
Whether you’re replacing a leaking cylinder or installing a modern, energy-efficient system, we’ll ensure everything is done to the highest standard with minimum disruption to your home.
Common Questions About Hot Water Cylinders
Can you run out of hot water with an unvented cylinder?
Yes, you can run out of hot water with an unvented cylinder.
An unvented cylinder stores a fixed volume of hot water (for example 170L, 210L, 250L, etc.). Once you’ve used most of that stored hot water, the cylinder needs time to reheat.
Whether you notice depends on:
- The cylinder size.
- The boiler output or immersion heater.
- How many people are using hot water.
- Whether multiple showers, baths, or appliances are running at the same time.
Typical examples
- A 210L unvented cylinder will usually provide enough hot water for 2–4 people, but a couple of baths and showers in quick succession can deplete it.
- If the cylinder is heated by a modern gas boiler, recovery can be relatively quick (often 20–40 minutes for a substantial reheat, depending on the setup).
- If it’s relying solely on an immersion heater, reheating can take several hours.
Signs the cylinder is running out
- Hot water temperature gradually drops during a shower.
- The first shower is hot, but later showers are lukewarm.
- Baths don’t fill as hot as expected.
Common causes if customers are running out unexpectedly
- Cylinder thermostat set too low.
- Programmer not giving enough heating time.
- Failed immersion or boiler controls.
- Scale build-up reducing heat transfer.
- Faulty motorised valve preventing full cylinder heating.
- Cylinder undersized for household demand.
For a plumbing and heating engineer, one of the first checks is whether the cylinder is actually reaching its target temperature (typically around 60°C) before usage begins.
If you have a particular cylinder model or size in mind, I can estimate roughly how many showers or baths it should provide before running out.
Is an unvented cylinder a good idea?
Yes — an unvented cylinder is generally a very good idea, but only if it’s installed in the right property and designed properly.
Here’s a clear, practical breakdown (from a plumbing point of view):
👍 Why unvented cylinders are good
1. Strong mains-pressure hot water
Because it runs directly off the mains:
- Powerful showers (like a mains shower pump, but without a pump)
- Good flow to multiple bathrooms
- Better performance than gravity-fed systems
2. No cold water tank in the loft
- Frees up loft space
- No risk of frozen loft tank in winter
- Cleaner system (sealed water supply)
3. Better for modern homes
- Works well with combi or system boilers
- Ideal for homes with 2+ bathrooms
4. Faster recovery (usually)
- Heats up quickly when paired with a decent boiler
- Can cope with back-to-back showers if sized correctly
⚠️ Downsides / things to be aware of
1. You can still run out of hot water
It’s not endless — it’s a stored volume system
- 150–300 litres typical
- Once it’s used, you wait for reheating
2. Requires good mains pressure and flow
If your mains is weak:
- Showers may underperform
- Cylinder may struggle to refill properly
3. Needs annual servicing (important)
Unvented cylinders are pressurised systems, so legally and practically:
- Must have safety valve checks
- Expansion vessel checked
- Temperature/pressure relief valve tested
- Ideally serviced annually by a qualified engineer
4. Higher install cost
Compared to vented systems:
- More components (safety valves, expansion vessel, controls)
- More skilled installation required
5. Safety regulations
Because it’s a sealed pressurised system:
- Must be installed by someone with the correct qualification (G3 in the UK)
🏠 When it’s a great choice
An unvented cylinder is usually ideal if:
- You have 2+ bathrooms
- You want strong showers without pumps
- You have decent mains water pressure
- You want a modern, efficient heating system
🧠 Simple summary
- ✔ Better pressure and performance
- ✔ More modern and reliable setup
- ❌ Not unlimited hot water
- ❌ Needs correct installation and maintenance
What are common unvented cylinder problems?
🔧 1. Low hot water pressure or flow issues
Common causes:
- Partially closed isolation valve
- Blocked inlet filter
- Mains water pressure too low
- Faulty pressure reducing valve (PRV)
👉 This is one of the most common “customer complaints” even when the cylinder itself is fine.
💧 2. Water coming out of the tundish (discharge pipe)
If water is dripping or flowing from the tundish, it usually means a safety device has activated.
Causes:
- Expansion vessel has lost charge (very common)
- Faulty temperature & pressure relief valve (TPRV)
- System over-pressurising when heating up
- PRV set too high or failing
⚠️ This is important — it’s a safety issue, not just a nuisance leak.
🔥 3. No hot water or lukewarm water
Common causes:
- Immersion heater failed
- Boiler not heating the cylinder coil
- Programmer/timer not calling for heat
- Motorised valve stuck closed (very common in system boilers)
- Thermostat fault
🚿 4. Running out of hot water quickly
Causes:
- Undersized cylinder for household demand
- Thermostat set too low
- Boiler not fully heating the cylinder
- Heat exchanger issues reducing recovery rate
- High simultaneous demand (multiple showers)
🔊 5. Noisy cylinder / banging or knocking
Causes:
- Scale build-up on immersion heater
- Air in system
- Expansion vessel issues
- Pipework expansion noise due to poor clipping
⚙️ 6. Pressure issues (too high or fluctuating)
Causes:
- Faulty expansion vessel
- Incorrect air charge
- PRV failing
- Check valve allowing back pressure
🚨 7. Safety valve or discharge pipe problems
Symptoms:
- Constant dripping outside
- Tundish flowing regularly
Causes:
- Worn TPRV
- Incorrect installation
- Expansion system not working correctly
🧠 What matters most in practice
In real jobs, the top 3 failures you’ll actually see most often are:
- Expansion vessel issues (loss of charge)
- Motorised valve or controls failure
- Thermostat or immersion heater faults
⚡ Simple takeaway
Unvented cylinders are reliable, but they are:
- Pressure systems (so small faults show up clearly)
- Heavily dependent on safety components working correctly
- Very sensitive to expansion vessel condition
How do I know which cylinder I need?
That depends on your household size, hot water usage, and existing plumbing. We offer free consultations to help you choose the right system.
How long does installation take?
Most installations are completed in a single day. If additional plumbing or electrical work is needed, we’ll let you know upfront.
Can I switch from a vented to an unvented cylinder?
Yes – in most cases, it’s possible. You may need upgrades to your plumbing or a new pressure-reducing valve. We’ll inspect your system and advise you on what’s required.
Areas We Cover
We install hot water cylinders across Liverpool, including:
| Aigburth | Aintree | Aintree Village | Allerton |
| Anfield | Belle Vale | Blundellsands | Bootle |
| Bowring Park | Brighton-le-Sands | Broadgreen | Burscough |
| Childwall | Clubmoor | Crosby | Croxteth |
| Croxteth Park | Dingle | Dovecot | Edge Hill |
| Everton | Fairfield | Fazakerley | Ford |
| Formby | Garston | Gateacre | Gillmoss |
| Grassendale | Great Altcar | Hale | Halewood |
| Hightown | Hunts Cross | Huyton | Ince Blundell |
| Kensington | Kirkby | Kirkdale | Knotty Ash |
| Knowsley Village | Litherland | Little Altcar | Little Crosby |
| Liverpool City Centre | Lunt | Lydiate | Maghull |
| Mawdesley | Melling | Mossley Hill | Netherley |
| Netherton | Norris Green | Old Swan | Ormskirk |
| Orrell | Orrell Park | Page Moss | Prescot |
| Rainhill | Roby | Scarisbrick | Seaforth |
| Sefton Park | Sefton Village | Speke | St Michaels Hamlet |
| Stockbridge Village | Stoneycroft | Tarbock | Thornton |
| Toxteth | Tuebrook | Vauxhall | Waddicar |
| Walton | Waterloo | Wavertree | West Derby |
| Whiston | Woolton | Widnes | All Areas of Liverpool |
If you’re not sure whether we serve your area, just get in touch — we’re happy to help.
Get a Free Quote Today
Whether you need a new installation, urgent repair, or just expert advice, we’re here to help. Contact us today for a free, no-obligation quote.
📞 Call us on: 07927062866
📧 Email: harrisjohnpaul@yahoo.co.uk
📝 Or use our [online contact form] to request a callback.
Why Upgrade Your Hot Water Cylinder?
Modern hot water cylinders are more efficient, more compact, and better at retaining heat than older systems. If your current setup is:
- Over 10–15 years old
- Slow to heat up
- Losing pressure
- Leaking or corroding
…it may be time for an upgrade. A new system could reduce your energy bills and improve your home’s hot water performance.
Let’s Get Started
We’ve helped hundreds of homeowners and landlords across [your region] install reliable, long-lasting hot water cylinders. Let us help you too. Get in touch for expert advice, fast installation, and fair pricing.
Are Unvented Hot Water Cylinders Safe?
Hot water creates a great deal of pressure within an unvented cylinder. If this builds up to dangerous levels, the tank could split. A pressure relief valve helps prevent this from happening by allowing excess pressure to be vented. If the valve fails, this cannot happen, though.
Unvented Hot Water Cylinders G3 (Builders)
G3 UNVENTED CYLINDER HEATING SYSTEMS Qualified INSTALLER. Unvented cylinder heating systems must be installed by a competent and qualified G3 qualified engineer
What Is The Difference Between Vented And Unvented Hot Water Cylinders?
A vented cylinder has a tank in the loft which feeds the hot water cylinder in the airing cupboard. The problem with this type of system is the pressure is not very good and needs a pump to give you better showers etc. which can be noisy especially first thing in the morning.
An Unvented cylinder is much better as it feeds off mains pressure so no need to have a seperate tank feeding with water. This means you get really good pressure at all your tap outlets and you will get a high pressured shower.
How Much Is An Unvented Hot Water Cylinder?
They range from around £300 – £3000 depending on the size and the manufacturer. We can go over how many bathrooms you have and people living in your home to decide the best litre capacity.