Why Unvented Cylinder Conversion Is a Superior Alternative to Gravity Fed Systems, Copper Cylinders and Shower Pumps

Why Unvented Cylinder Conversion Is a Superior Alternative to Gravity Fed Systems, Copper Cylinders and Shower Pumps

Older homes across the UK often rely on gravity fed water systems, where water is stored in a cold water tank in the loft and supplied to taps and showers using gravity. These systems suffer from low water pressure, noisy shower pumps, hygiene and maintenance issues.

Unvented hot water cylinders offer a high performance, energy efficient, and hygienic solution.  Below, we outline the compelling reasons for converting from a gravity fed system, copper cylinder, and shower pump to an Unvented Cylinder.

Benefits of Unvented Cylinder Conversions

1. Consistent High Water Pressure (No More Shower Pumps)

Gravity fed systems are known for poor water pressure, often requiring the addition of shower pumps to boost flow. However, these pumps are:

• Noisy and disruptive –  sometimes waking up occupants at night as the pump activates each time a tap is turned on
• Expensive to install and run – pump use electricity each time a tap is turned on
• Prone to frequent failures  – high maintenance and expensive to replace

Unvented cylinders are connected directly to the mains water supply, delivering consistently strong pressure throughout your property, two to three times higher than gravity fed systems, eliminating the need for shower pumps altogether.

2. Quiet, Maintenance Free Operation

Unvented systems do not rely on loft tanks or shower booster pumps. With no moving parts like motors or impellers, you benefit from a silent hot water system. This creates a quieter home without a shower pump rattling every time a tap is turned on

3. Energy Efficiency and Lower Running Costs

Modern unvented cylinders feature triple layer insulation to reduce heat loss and maintain water temperature for longer. The result:

• Reduced energy bills
• Faster heat up times
• Extended lifespan and warranties up to 25 years

B-rated Unvented cylinders are far more energy efficient compared to older G-rated uninsulated copper cylinders – saving up to £400 a year on energy bills immediately.

4. Space Saving and Reduced Leak Risks

Removing the cold water tank from the loft does not just free up usable space, it also reduces the number of pipe runs, joints, and valves, all of which are common sources of leaks in gravity fed systems.

By simplifying the plumbing and removing long vertical pipework from the loft, you:

• Reduce the potential for hidden leaks
• Improve system reliability
• Create more space for storage or loft conversions

5. Improved Water Hygiene and Elimination of Contamination Risks

While pressure and performance are key reasons for upgrading, the health hazards associated with gravity fed systems are often overlooked.

Cold water storage tanks in lofts are open to the elements and poorly protected. Over time, they become vulnerable to:

• Stagnant water and bacterial growth
• Rodents, spiders, and insects entering to drink from or nest near the water
• Debris and dust buildup
• Dead animals, including pigeons and rodents, contaminating the water supply

At Boilergurus, we have found dead pigeons and animal bones inside loft cold water tanks when decommissioning and draining down the cold water storage tank  — a shocking but not uncommon issue.

These tanks also create ideal conditions for Legionella bacteria, which thrives in warm, stagnant water and causes Legionnaires’ disease, a serious respiratory infection spread via water droplets.

Therefore in properties with gravity fed systems that rely on a cold water storage tank, occupants should avoid drinking water from any tap except the kitchen tap, as it is typically the only outlet supplied directly with clean mains water.

Switching to an unvented cylinder eliminates the cold water tank entirely, ensuring:

• Fresh, mains fed water at all outlets, not just the kitchen tap
• Stronger and more consistent water pressure throughout the property
• No stored water at risk of contamination from dust, debris, or animals
• Elimination of shower pumps, reducing noise and maintenance
• Improved system hygiene, reducing the risk of Legionella’s disease
• Faster heat up times and greatly reduced energy loss due to modern insulation
• More loft space and simplified plumbing, reducing the chance of leaks
• Greater peace of mind through improved safety, reliability, and water quality

Conclusion

If your property still relies on a gravity fed system, copper cylinder, or noisy shower pump, upgrading to an unvented cylinder provides multiple benefits. By removing the cold water storage tank and switching to a mains fed system, you gain:

• Clean, fresh water at all outlets
• Strong and consistent water pressure throughout the property – 2 to 3 times more.
• Quieter operation with no need for shower pumps
• Simplified plumbing with fewer leak risks
• Faster heat up times
• Triple insulated for energy efficiency
• More usable loft space and reduced maintenance
• Eliminate the risk of Legionella’s disease, which can develop in stagnant cold water tanks and pose a serious health threat to occupants.

While Legionella and water hygiene are important, they are just one of several compelling reasons to upgrade. From enhanced performance to energy savings, unvented cylinders represent the modern standard for domestic hot water systems.

What is Legionnaires’ Disease?

Legionnaires’ disease is a serious and potentially fatal lung infection caused by inhaling tiny droplets of water contaminated with Legionella bacteria. These bacteria thrive in stagnant or warm water environments, such as poorly maintained cold water storage tanks, hot tubs, or plumbing systems where water is not regularly circulated.

How Does it Spread?

Legionella is not spread from person to person. Instead, infection occurs when a person inhales aerosolised water droplets containing the bacteria, typically from:

• Showers or taps connected to contaminated tanks
• Water systems with poor temperature control or low flow
• Mist from air conditioning or cooling systems

Health Risks and Long-Term Effects

Legionnaires’ disease begins with flu-like symptoms, including:

• High fever and chills
• Cough and shortness of breath
• Muscle aches and headaches
  

In more severe cases, it can cause:

• Pneumonia
• Respiratory failure
• Septic shock
• Hospitalisation and intensive care
  

People at greater risk include:

• Older adults (especially over 50)
• Smokers
• People with weakened immune systems or chronic respiratory conditions

How People Contract Legionnaires’ Disease

Legionnaires’ disease is caused by inhaling water droplets that contain Legionella bacteria. This usually occurs when contaminated water is turned into aerosol mist through everyday household activities.

In a domestic setting, people can unknowingly inhale contaminated droplets from:

• Showers – especially if water has been standing in pipes or tanks
  
• Taps – particularly in little-used bathrooms or if the system hasn’t been flushed
  
• Toilets – fine water mist from flushing can carry bacteria into the air
  
• Bidets or sprayers – another potential source of airborne droplets
  
• Any outlet connected to a contaminated cold water tank or pipework
  

The risk is highest when:

• Water remains in storage tanks or pipes for long periods without use
• Water temperatures between 20°C and 45°C create ideal conditions for Legionella bacteria to thrive — This temperature range is commonly found in cold water storage tanks, especially in lofts during spring and summer months. As outside temperatures rise, stored cold water can warm up and remain stagnant, providing a perfect breeding ground for bacteria. While the water is eventually heated in the copper cylinder to around 60°C–70°C, this does not kill the bacteria that have already developed in the stagnant cold water storage tank.
• The system contains scale, sludge or organic matter that supports bacterial growth

• In gravity fed systems, this is a common scenario, especially during warm months. Cold water storage tanks in lofts are particularly vulnerable due to poor insulation, inconsistent temperatures, and lack of regular cleaning or inspection.

Once airborne, Legionella bacteria can travel directly into the lungs when a person breathes in steam or mist during a shower or while running taps. It only takes a small amount of exposure for infection to occur.