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Boiler economiser

Wednesday, June 10, 2015   By: Kishan Nandania


Please i want to know what is the difference between external economiser and internal economiser in detail, please suggest me points.

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Hello,Please i want to know what is the difference between external economiser and internal economiser in detail, please suggest me points.

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Wednesday, June 10, 2015   By: Ross Burns [390]


The way I look at an integral economizer is, this type of boiler economizer is a part or inside the boiler -casing-, also the integral economizer heating surface replaces some of the boilers heating surface. Large steam generators or boilers usually have integral economizers.

A unit economizer is like you described as a bolt-on unit to the boiler and is not integral to the boiler casing. Small industrial boilers tend to have unit economizer or as you said external boiler economizers.

A few years back, I was consulting for a university on their HTHW Boilers - LaMont Type - and 2 of them had integral economizers or internal as you called it. Could not see the integral economizer until the boiler outer and inter casing was removed.


Ross Burns

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Kishan, I think what you said external boiler economizer is also referred as a unit economizer, and an internal boiler economizer is an integral economizer.The way I look at an integral economizer is, this type of boiler economizer is a part or inside the boiler -casing-, also the integral economizer heating surface replaces some of the boilers heating surface. Large steam generators or boilers usually have integral economizers.A unit economizer is like you described as a bolt-on unit to the boiler and is not integral to the boiler casing. Small industrial boilers tend to have unit economizer or as you said external boiler economizers.A few years back, I was consulting for a university on their HTHW Boilers - LaMont Type - and 2 of them had integral economizers or internal as you called it. Could not see the integral economizer until the boiler outer and inter casing was removed.Ross Burns

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Wednesday, June 10, 2015   By: cmolanes@itba.edu.ar [50]


The comments given by Mr. Ross Burns must have given you already a clear idea of these economisers. Only adding a little more, if you have, or plan to have, an external, or unit economizer, these have inherently easier access for maintenance and repairs, and depending on your fuel, the acid attack, by sulfuric acid, is perhaps an unavoidable event.

As for built-in economisers, I suspect that they are always built together with the boiler, so I do not imagine that there be space to mount one afterwards in an existing boiler, exception made of some smoke-tube boiler in which you may plan to install one in the smoke chamber prior to the stack.

If your need is to install one, please consider that they are usually designed with finned tubes to increase the heat transfer on the gas side, water circulating within the tubes, and you must provide some soot-blowing equipment as well.

Claudio Molanes

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Mr.Nandania:The comments given by Mr. Ross Burns must have given you already a clear idea of these economisers. Only adding a little more, if you have, or plan to have, an external, or unit economizer, these have inherently easier access for maintenance and repairs, and depending on your fuel, the acid attack, by sulfuric acid, is perhaps an unavoidable event.As for built-in economisers, I suspect that they are always built together with the boiler, so I do not imagine that there be space to mount one afterwards in an existing boiler, exception made of some smoke-tube boiler in which you may plan to install one in the smoke chamber prior to the stack.If your need is to install one, please consider that they are usually designed with finned tubes to increase the heat transfer on the gas side, water circulating within the tubes, and you must provide some soot-blowing equipment as well.Claudio Molanes

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