Combi Boilers
A 'Combi' boiler is called this because it heats water for your radiators and heats water for your taps on demand.
This means that when you run the hot tap your boiler fires up and heats that water that will help you wash up or clean your hands.
At the same time it could be heating your home's radiators so doing 2 things in 'combi'nation.
The benefits are:
- Can be cheaper to run as there is no hot water store to heat
- Heating for radiators and Hot water for your taps when you want it
- No need for a separate hot water cylinder, saving space
When a Combi may not be suitable:
- If your property has low mains water pressure
- If your property has multiple bathrooms/Shower rooms
System Boilers
These boilers are the modern day equivilent of the conventional boiler which heat radiators to give us warmth and heat a coil inside a cylinder to give us hot water.
The advantage with a system boiler is that it uses a sealed 'system' which moves the water more quickly and more efficiently so being more economical. We can use valves to zone out a system thereby allowing different area to be heated at different times or temperatures too.They also dispense with a storage tank and so may be easier to install.
Customers that live in larger properties or have multiple bathrooms and showers would benefit from having a system boiler over a combi because of the stored hot water facility which allows for much better water flow rates.
Customer who want to 'go green' would also benefit from system boilers because these boilers can be 'linked ' to solar thermal, geo thermal and wood burning systems to give us complete dexterity over the type & use of fuel we use to keep us warm .
Cylinders
Pipe work from the central heating boiler takes water through a coil inside the cylinder to give us hot water.
Cylinders are well insulated nowadays so there is not much heat loss and they come in a variety of sizes to suit all manner of households.
The best type of cylinder is the unvented cylinder because this type uses cold mains pressure to send hot water around the home. This means we can have fantastic flow rates to baths & showers and multiple bathrooms & showers.
These cylinders can be sited anywhere and commonly are installed into the loft space which saves space and allows easy link up to Solar thermal at a later stage.
Unvented and Vented
Unvented cylinders must be installed by qualified engineers because they require a high degree of expertise and come with a number of safety controls which need to be installed correctly to give safe operation.
Another advantage with unvented cylinders is that we can add a second coil to the cylinder which can be utilised for Solar thermal or even just link this to the heating like the first coil to give a fast heat up.
There are also thermal stores on the market and these utilise the heating water inside a cylinder and these are more specialised but for the right customer provide a perfect system which can utilise various forms of 'green energy' Wood burning stove for example can be liked to a thermal store to provide free hot water every time the stove burns wood. This system could also be linked to Solar thermal to provide free hot water all year round!
Whilst vented hot water cylinders need a store of cold water, unvented cylinders get their water directly from the water mains.
The water mains feeds the hot water cylinder, this in turn heats that water, using either your boiler, or in some cases an immersion heater. Then when you need hot water it releases its store of warm water to your taps, the mains, in turn, refills the cylinder.
The Benefits are:
- No need for a store of cold water
- Higher water pressure
- Simpler plumbing
- Power showers without the need for a pump
In simple terms with a vented hot water cylinder you have a store of cold water usually in the loft that feeds the hot water system.
The hot water system is often heated by a gas or oil boiler. Some renewable systems, such as Solar Thermal, can be used. The pressure is gained through gravity, so the height of the cold water store above the hot water cylinder creates the momentum that pushes that water out of your taps.
The benefits for this type of system are:
- Easy to install
- Low maintenance
- Simple mechanism
The potential drawbacks are:
- You have to have a cold water store, usually in the loft
- Hot water flow rates may be low especially if pipes are not adequately sized