How Do Hot Water Cylinders Work?

What are the different types of hot water cylinder?

The type of hot water cylinder you have will determine the way in which the water enters it. 

Unvented cylinders are storage systems that feed off the mains water pressure, meaning that they don’t need a cold-water storage tank. This makes them more compact than other systems that need additional space in lofts. 

Thanks to the connection to the water mains, hot water flow rates and water pressure are high, which is why they have been popular since they were first introduced in the 1980s.

Vented hot water cylinders receive water from an external cold water tank, or header tank, which is usually stored in the loft. This system is usually found in the loft because it uses gravity to build pressure, rather than it being generated at the mains. 

It is called a vented hot water cylinder because a vent pipe is used to connect the cylinder to the cold water tank. 

What is the difference between a direct and an indirect hot water cylinder?

Direct hot water cylinders are designed with an immersion heater within the cylinder itself. These cylinders heat the water directly, and some even use multiple heaters to keep the water hot. 

Indirect hot water cylinders however, are a type of hot water cylinder that require an external source of heat, which is usually the boiler. Indirect hot water cylinders can also be fitted with an immersion heater as a back up heater. 

How do hot water cylinders work?

Essentially, a hot water storage cylinder works as follows:

1. It contains pre-heated hot water.
2. It draws cold water in from one pipe.
3. It then heats the water through the use of your boiler, an internal immersion heater or solar thermal process, and then stores it until required.  

Should I have a hot water cylinder?

If you have a system or open vent boiler, heat pump, or solar hot water solutions then you will need a hot water cylinder installed as part of your heating and hot water system. 

If you own a home with two or more bathrooms and a high demand for a constant supply of hot water, then installing a hot water cylinder will always ensure that your needs are met. 

If you live in a property with low pressure and a pump is needed to support the flow of water, a hot water cylinder will ensure that water is delivered at the right temperature. 

What is the lifespan of a hot water cylinder?

Hot water cylinders typically come with a minimum 25 years guarantee, but they can last longer if they’re well maintained. 

A heating engineer will carry out annual comprehensive checks for you to see if the hot water tank needs replacing. 

What size hot water cylinder do I need?

Finding the right size hot water cylinder is vital. It needs to be large enough to handle the demand for hot water usage in your home, but small enough so that you’re not wasting energy heating and storing more water than you need. 

Both vented and unvented hot water cylinders are available in a range of sizes, varying anywhere between 74 litres to 450 litres. 

• Unfortunately, there is no one-size-fits-all with hot water cylinders, so when deciding what size you’ll need, the general rule of thumb to follow is allowing 35-45 litres of water per household occupant.

How do I know if my hot water cylinder needs replacing?

Although hot water cylinders can be reliable, they can also be prone to irreparable problems over time. Signs you can look out for are:

Cold water

If your home has a direct water cylinder, then cold water could be a clear sign that there is an issue with the internal heating element. This element will usually wear down over time and may need replacing by a Gas Safe Registered (GSR) engineer, like our team at Lacey Plumbing & Heating.

If your hot water cylinder is nearing 8-12 years, it is advisable to have the cylinder checked by a heating engineer to see if there’s any signs or wear and tear and to check it’s working efficiently.

Leakages

If you spot a leak coming from your hot water cylinder, we recommend you arrange for a heating engineer to inspect your system as soon as possible. Leaks can be dangerous, and they also indicate that there is an internal issue that may be tough to repair. 

Strange noises 

Limescale builds up in cylinders over time and can cause blockages. If your system is not regularly maintained, you may experience a significant build-up that creates strange noises when the water is heated and flows through the system. 

This can usually be flushed out and treated by an engineer, but it could cause damage if left untreated. 

Discoloured water 

If the water running from your taps is discoloured or smelly once heated, this may be a sign that the anode rod inside is defective and needs to be replaced. 

At Lacey Plumbing and Heating, we provide hot water cylinder installation, servicing and maintenance. 

Our professionally trained and experienced team will provide the best service possible, ensuring all your water cylinder issues are resolved as soon as possible. 

Get in touch with us to find out more about having hot water cylinders installed or repaired.