History behind unvented cylinder







1861 - As is often the case, the unvented hot water cylinder was a British invention – Sir Thomas Hawksley coming up with the idea in 1861. However, the British establishment immediately noticed that storing hot water under pressure could lead to certain 'issues', not ...As is often the case, the unvented hot water cylinder was a British invention – Sir Thomas Hawksley coming up with the idea in 1861. However, the British establishment immediately noticed that storing hot water under pressure could lead to certain 'issues', not least of which was the opportunity for the storage device to explode. It was therefore decided that the unvented cylinder was far too dangerous to be put into British homes and that Sir Hawksley ought to go off and ...





Sep 17, 1959 - of cold weather each year deaths result needlessly from this cause Mr Rosenberg's warning is timely and should not be ignored If landlords are risking the lives of their tenants with unvented heaters they should be brought to face the full penalties of the law ... From The Unvented Heater Part Of The Laos Story . - Related web pages




Mar 1, 1970 - DINUBAAn unvented gas heater in a closed three miles north of here asphyxiated four members of a family Sat urday according to the Tulare County coroner s office. Dead were Wayne John ston 28 his wife Freda 24 who was seven months pregnant their son Gene 1 and Mrs Johnston's mother Mrs ... 




Nov 26, 1978 - The gas company has stopped ser vicing unvented gas room heaters and willred tag as unsatisfactory any such units found during routine ser vice ... A 1970 state law prohibited the sale of unvented heaters Hill said but a rising number of incidents involving the appliances has spurred ... 




May 17, 1982 - ... ... In a declaratory judgment action brought by a corporation which had been ordered to refrain from selling unvented space heaters for any use by ... history of the statute governing space heaters and stoves indicates that the statute was enacted to prohibit the sale of unvented space ... 




Jan 29, 1983 - A man living in the apartment, Clendon mcneely told police that when he left for Police Chief Bud Henton said it was probably the worst tragedy in the city's history involving a single family. Mrs. Liles said she had used the heater in her house before it was placed in the apartment. ... 




Nov 11, 1985 - Unvented Cylinders are covered by section G3 of the Building Regulations. G3 of the Building Regulations came into force on November 11th 1985. Advantages and Disadvantages of unvented systems.




Nov 8, 1995 - right now is that wed rather be safe than sorry Ziegler said he would never sell a hazardous product But 4 million units have been sold nationally without ill effect Ziggy's is not the only store that sells unvented gas fireplaces but it's the only one complaining to city hall ... 




Nov 14, 1999 - Wood Burning or Unvented Gas Stoves Wood unit is compact and mighty It will heat up to 1.000 sq and has a large viewing glass It burns logs and uses a 6 flue The gas units are unvented and heat approximately 900 sq. 



Aug 11, 2005 - 4524.39.2 Unvented portable space heatersaUnvented portable space heater as used herein shall mean a nonflue connected selfcontained self supporting oilfueled heating appliance equipped with an integral reservoir designed to be carried from one room to anotherbOil as used herein shall ... 



Unvented Hot Water Cylinders - Benefits

Unvented Cylinders (or pressurised tanks) are not vented by an external body, but rather use a pressurised system to move the domestic hot water. Unvented cylinders therefore use the water mains pressure ensuring sufficient pressure of hot water even in higher floors and without the need for a header tank in the loft.

Benefits of Unvented Cylinders:

Higher hot water flow rates – unvented cylinders offer higher pressure for the shower, bath, kitchen etc.

Freeing up space in the loft – unvented cylinder removed the need for header/feeder tank

Flexible installation location – unvented cylinder can be installed anywhere in the house, for example in the garage (freeing up space in the airing cupboard)

Quieter mains pressure system – as unvented does not require external feeder tanks, there is no noisy cistern in the loft

No frozen pipes in the loft – unvented cylinders mean there are no tanks or pipes exposed to freezing temperatures in the loft.

Unvented tanks are simple to install

Unvented cylinders are engineered to have a long lifetime, which ensures good value for money



Un-vented hot water heating systems




When an un-vented hot water system is installed both the hot and the cold water supplies within the dwelling, deliver water at the taps or shower outlet at mains water pressure. Cold water from the mains is delivered to the base of the cylinder, the water is heated, then when a tap or shower is turned on the mains water pressure pushes the hot water out.





To allow the water that is heated in the cylinder to expand as it is heated, an internal or external expansion vessel is used; a pressure relief valve is also fitted should the vessel fail.

An un-vented hot water storage cylinder can be heated directly via an immersion heater or indirectly by most heating systems providing it is not a solid fuel burning appliance They are ideal where high performance is required or in multi story properties where it would be difficult to gain the necessary head of water via a cold water storage tank to feed taps on the upper floors.









Balanced pressures at hot and cold taps.

High performance showering throughout the house.

High pressure and hence flow rate of hot water.

Fast filling baths.

Potable (drinking) water at all taps.

No cold water storage therefore no contamination.

Quicker to install Quiet running Fast recovery (typical 15-20 mins for 125L)

No fear of frozen loft pipes


No storage back up if mains water fails.

Poor mains water pressure will cause poor performance.

Need for discharge pipe (overflow) Requires high level of maintenance