Conventional Boilers

A Conventional Home Heating Solution

The main factor that sets a Conventional boiler apart from a combi or system boiler is it does not operate on a sealed system, the vented system is subject to external atmospheric pressure and can be called “Open Vent”.

Typically, a Conventional Open vent heating system will have two cold water storage tanks; a large one for the hot water cylinder which refills the cylinder when the hot water tap is used and a smaller tank which connects to the boiler and radiators. This smaller tank allows the water in the radiators to expand. This is commonly referred to as the “expansion tank” or “Feed tank”. It is also where the “open vent” is located. This vent is a simple piece of pipe which allows water from the system to be expelled if it gets too hot. Any hot water ejected will fall safely back into the expansion tank.

Advantages of a Conventional Boiler

- Open vent boilers can be small in comparison to a combi or system boiler. This smaller size allows them to be fitted in tight spaces; for example kitchen cupboards.
- Open vent boilers don’t have a built-in pump like a system or combi boiler which means they have more flexibility when designing a large heating system.
- High flow rates of domestic hot water
- More than one tap, shower or outlet, in general, can be run at the same time without any adverse effect on water pressure or flow
- These systems can support a backup heater, such as an immersion heater and is Compatible with solar thermal.

Disadvantages of Conventional Boilers

- Once the hot water in the storage cylinder is depleted you must wait for it to refill and reheat
- Space is needed for the storage cylinder and cold water tank in the loft or airing cupboard
- Fitting a new open vent system in a property requires more plumbing, and therefore more labour than Combination or System Boiler heating systems
- As the tanks are often in the loft space, freezing pipework is a risk if the home is left unheated for extended periods in very cold weather.
- Due to all of its separate parts and pipework, a conventional boiler system is one of the more time consuming and costly heating systems to install.

Who are Conventional Boilers Suitable For?

- Properties that have a large family with multiple occupants requiring multiple sources of hot water simultaneously
- Properties that have older pipe systems that may not handle pressurised sealed systems
- Properties where you are replacing an existing Conventional boiler - in an older property, a conventional boiler can be a good option as it requires minimal changes to the pipework, if any.

A fresh installation of an open vent boiler for the majority of homes is uncommon due to all the storage tanks and hot water cylinders required and the time and cost to install them.