Vented or unvented hot water tank: what’s the difference?
If you have a hot water tank in your home, it will usually be either vented or unvented.
You might also hear these called hot water cylinders, but most people simply know them as the tank in the airing cupboard.
The difference between the two affects how water gets into the tank, how it reaches your taps and showers, and the kind of water pressure you can expect.
How you store hot water matters just as much as how you heat it.
What does a hot water tank do?
A hot water tank stores heated water so it’s ready when you turn on a tap, have a shower or fill a bath.
The main difference between vented and unvented tanks is how they get their cold water supply.
What is a vented hot water tank?
A vented hot water tank is usually fed by a separate cold water tank, often found in the loft.
Water travels down from the loft tank into your hot water tank and is then heated ready for use.
Because the system relies partly on gravity, the water pressure at your taps and showers can sometimes be lower.
You may have a vented system if you have:
A hot water tank in an airing cupboard
A separate water tank in the loft
Hot water pressure that feels lower than your cold water pressure
Vented systems are very common, particularly in older homes, and there’s nothing wrong with keeping one if it works well for you.
What is an unvented hot water tank?
An unvented hot water tank is connected directly to your mains water supply.
There’s no need for a separate cold water tank in the loft.
Because the water comes directly from the mains, an unvented tank can often give you stronger hot water pressure at taps and showers.
That can make a noticeable difference in homes with multiple bathrooms or where more than one person may be using hot water at the same time.
Does an unvented tank automatically mean better pressure?
Not always.
An unvented tank can only work with the water supply coming into your home.
If the incoming mains pressure or flow is poor, simply changing the tank won’t automatically solve the problem.
That’s why we look at things like:
Your mains water pressure and flow
How many bathrooms you have
How much hot water your household uses
Your existing pipework
Your boiler
Where the tank is located
The hot water tank is only one part of the picture.
The best results come from making sure the whole system works together properly.
Should I replace my vented tank with an unvented one?
Not necessarily.
If your current hot water tank works well and gives your household enough hot water, there may be no need to change it.
An unvented tank may be worth considering if you’re:
Renovating your home
Adding another bathroom
Replacing an old tank
Looking for better hot water pressure
Removing a water tank from the loft
Changing your boiler or heating system
The right option depends on your home and how you use it.
Are unvented hot water tanks safe?
Yes, when they’re installed and maintained correctly.
Because an unvented tank stores hot water under pressure, it has specific safety controls built into the system.
That means installation and servicing should be carried out by someone appropriately qualified to work on unvented hot water systems.
What if I don’t know which type I have?
That’s completely normal.
Most people don’t need to know what type of hot water tank they have until something goes wrong or they’re considering an upgrade.
If you’re not sure, we can take a look at what’s already installed and explain it in plain English.
Sometimes upgrading makes sense.
Sometimes the best advice is to leave a perfectly good system exactly as it is.
Better hot water starts with the right set-up
The best hot water system isn’t necessarily the newest or most expensive.
It’s the one that works properly for your home.
If you’re replacing a hot water tank, renovating, struggling with water pressure or simply want to understand what you already have, talk to the Westflow team.
We’ll look at the whole set-up, explain your options clearly and help you decide what makes sense.