The rare economiser type differed in that it extracted residual heat from the exhaust gases.
From the en.wikipedia.org
But when she moved in, she could be seen inspecting its fittings with that look of a born economiser.
From the thisismoney.co.uk
The engine needed more space and the engine house, boiler house and economiser were built external to the main mill.
From the en.wikipedia.org
In 1908 he started a motorcycle business in Invercargill and fitted the imported bikes with his petrol economiser.
From the odt.co.nz
His petrol economiser, or Vaporizer, was commercially successfully and in 1929 there was special satisfaction when the city of Philadelphia had it fitted in some 580 buses and 3000 taxis.
From the odt.co.nz
More examples
Economizer: a frugal person who limits spending and avoids waste
Economizers (US), or economisers (UK/international), are mechanical devices intended to reduce energy consumption, or to perform another useful function like preheating a fluid. The term economizer is used for other purposes as well. ...
It is a part of boiler. Its function is to heat feed water which is supplied to boiler.