English

Verb

underfire ‎(third-person singular simple present underfires, present participle underfiring, simple past and past participle underfired)

1. (transitive, intransitive) To heat from below.
   • 1856 May, William Kemble Hall, “On the Causes of Explosions of Steam Boilers”, in John F[ries] Frazer, editor, Journal of the Franklin Institute of the State of Pennsylvania for the Promotion of the Mechanic Arts. Devoted to Mechanical and Physical Science, Civil Engineering, the Arts and Manufactures, and the Recording of American and other Patent Inventions, volume LXI, Philadelphia, Pa.: Published by the Franklin Institute, at their hall, OCLC 620131291, page 299:

     It was contended, that the only objection which could be raised against under-firing, was the danger of incrustation, or deposit upon the boiler bottom, of matter held in suspension by the water; but that this rarely, if ever, caused explosions; the utmost injury it occasioned, was causing the boiler plate to be burnt out, and that this effect could not take place, without gross neglect.

2. (transitive) To intentionally operate a boiler, furnace, oven, etc., at a low level.
   • 1934, Wilbert J. Huff, “Gaseous Fuels during 1932 and 1933”, in A Survey of American Chemistry, volume VIII, New York, N.Y.: Chemical Catalog Company for National Research Council, OCLC 2394622, page 339:

     The large supply of natural gas at Chicago permitted underfiring the batteries of the Chicago By-Product Coke Oven Plant with a mixture of producer gas and natural gas. […] The mixing of by-product coke oven gas with blast furnace gas to correct the varying thermal deficiencies of the latter when used to underfire coke ovens is patented by Becker.

   • 1976 April, G. R. Offen [et al.], Control of Particulate Matter from Oil Burners and Boilers (EPA-450/3-76-005), Research Triangle Park, N.C.: Office of Air and Waste Management and Office of Air Quality Planning and Standards, Environmental Protection Agency, OCLC 2687268, page 1-19:

     One of the major factors contributing to high particulate emissions from domestic burners is on-off cycling. […] Underfiring consists of using a smaller (undersized) unit which has to stay on longer and, therefore, cycles less. However, no data are available on the effectiveness, cost, and public acceptability (more complex system or inability to heat house as comfortably during very cold periods) of these proposals.

   • 1989, Roger Loison; Pierre Foch; André Boyer, Coke: Quality and Production, 2nd edition, London; Boston, Mass.: Butterworth & Co. (Publishers) Ltd., ISBN 978-0-408-02870-7, page 467:

     It is generally accepted […] that underfiring of ovens with lean gas (generally blast furnace gas) leads to a greater heat consumption than underfiring with rich gas.

3. (intransitive) Not burning fuel at the desired level, and thus not providing heat efficiently.
   • 2012, Eugene Silberstein, Residential Construction Academy: HVAC, 2nd edition, Clifton Park, N.Y.: Delmar, ISBN 978-1-285-22526-5, page 680:

     If the burner is underfiring, the nozzle may need to be changed or the pressure at the outlet of the fuel pump may need to be adjusted.

4. (transitive, ceramics) To fire at a low (or excessively low) temperature.
   • 1973, Ceramic Industry, volume 101, number 2–6, page 68:

     You no longer need to underfire your products or guess at their high temperature behavior simply because of lag in furnace technology.

Derived terms

• underfired ‎(adjective)

Antonyms

• overfire