High temperature metal F&E and Header tanks | Tanks suitable for use with uncontrollable high temperature heat sources such as AGA and Wood Burning stoves

Header tanks suitable for use where temperatures could get high

What is the difference between a header tank and an F&E tank?

In a fully open vented heating and hot water system you will often find water storage tanks in the loft. It is quite common to find two. The function of each is however quite different.

You may well find that one tank (usually the larger of the two) is a Header Tank, whereas the other (the smaller) is a Feed and Expansion Tank (also known as an F&E tank).

Header tank

A Header Tank is a cold water storage vessel usually filled via a ball cock (or float valve) directly from the incoming cold water main. This tank stores the water that feeds to your hot water cylinder. The high position of the Header Tank creates 'a head' of water which determines the pressure of the hot water system in the property. System pressure can be calculated roughly by applying the following equation: Measure the vertical difference from the Header Tank to the point of outlet. A 10 metre differential will give 1 bar of pressure at the outlet, other height differentials can be calculated pro rata. Pressure can be raised by increasing the height the Header Tank in relation to the outlet.

F&E tank

A Feed & Expansion tank is typically connected to the 'heating' side (boiler or radiator circuit) of an open vented system allowing it to breathe. As its name suggests it provides a method of replacing (feeding) water that might evaporate as the system gets hot whilst accommodating expansion of the water contained within the system.

What should an F&E or Header Tank be made from?

Header tanks are commonly made from plastic, but can be made from a range of materials. Metal header tanks are better suited for use in systems where the water can become very hot due to the uncontrollable nature of the heat source. Such systems might include solid fuel installations, wood burning stoves, AGA, back boilers etc.

Use of a plastic tank in a scenario where water contained within could reach a high temperature is dangerous as the tank could sag or deform. In such an event boiling hot water could escape and pour through the ceiling below with devastating consequences. Using a metal Header or F&E tank safeguards against this awful scenario.

What are the advantages of a copper header tank?

A copper header tank is not susceptible to melting or warping when hot water is introduced. In systems where the water temperature can be high distortion can be a particularly dangerous problem. Systems that incorporate a solid fuel boiler or uncontrolled heat source such as a wood burner are capable of heating water in excess of 100°C. Serious accidents have occurred when cheap polythene header tanks have sagged, pouring boiling hot water through bedroom ceilings.

Antiseptic property of Copper

Copper has a property that is often overlooked by those who advocate stainless steel as the preferred metal. Heating systems can often become infected by all sorts of bacteria including Legionella bacteria - the cause of Legionnaire's disease. Copper possesses slight antiseptic properties that help fight against any 'nasties' that might want to live in the nice warm environment of your tank. Stainless possesses no such properties.

Should you insulate a Header or F&E tank?

One might argue, what is the point of insulating a Header tank or an F&E tank if the water in it is likely to be hot? Well, strangely it is a good idea.

Header and F&E water tanks commonly reside in spaces that are susceptible to super cold temperatures such as loft spaces. It is wise to protect any water storage vessel placed in a loft against freezing temperatures. Just as high temperatures might deform a plastic tank, freezing can easily split a metal one.

If a Header tank is un-insulated it can also act as a heat sink, drawing heat out of the system you have troubled to heat.

Having hot water in such a tank is not an issue provided the tank can cope. Wasteful heat loss is something to be avoided so insulation is recommended.

Square, oblong and bespoke header tanks

Metal header tanks can be manufactured to your design and/or specification. However, this is not a cheap option. With the rapidly rising cost of materials and the man-hours required to manufacture bespoke shapes you are encouraged to seek alternative solutions where possible that invariably work out cheaper.

For further information you are invited to call and discuss requirements.

Square copper header tank with lid