Header tanks or Primary Feed and Expansion Tanks, as they are often referred to, are designed to work with open vented cylinders and thermal stores. They act as an overflow facility when the temperature of the water increases and therefore expands.
The tanks can generally be manufactured in a range of materials including plastic and copper, however when it comes to thermal stores, the use of plastic header tanks can prove to be very dangerous.
With the stored water reaching in excess of 80 degrees Celsius, plastic header tanks are often not suited to cope with these high temperatures.
Not only can the main body of the tank start to soften and distort, damage to the plastic ballcock could render it useless and result in the hot water overflowing through the ceiling.
The potential impact of near boiling hot water coming through a ceiling can be catastrophic and a fatality in the past changed the regulations on Immersion Thermostats.
The risk is intensified when the system also features a solid fuel energy source such as a wood burning stove, where the temperatures can rise even further.
Copper on the other hand has a melting point of 1085ºC and therefore can cope with even the highest temperatures of any hot water system, making them the most reliable and durable system on the market today.
McDonald Engineers manufacture a standard range and also bespoke, copper Feed and Expansion Tanks with high temperature ballvalves and copper float.