The?Firebird?UK?System boiler which is manufactured in Ireland is also referred to as a ?sealed system boiler?, provides central heating and direct hot water via a storage cylinder, which is usually housed in an airing cupboard. Unlike a regular boiler heating system, there is no requirement to have water tanks situated in the loft. System boilers are generally easier to install, as the heating and hot water system components form an integral part of the boiler itself. The Envirogreen Systempac is similar in specification to the internal Envirogreen System, with the addition of a built-in frost thermostat. There is no requirement to house the boiler in a building, so this option provides an ideal solution if internal space is at a premium.