BY GEORGE LANTHIER

In classes during last year’ s training season, we were surprised to learn that many smaller companies have gone back to the use of the standard combustion test kit or‘ wet-kit’, Figure 1. Reasons given were the initial cost and maintenance of electronic analyzers and the simplicity of the wet-kit components.

We updated the material in this article to reflect current industry conditions and the fact that these kits were discontinued by MSA / Bacharach in March of 2023. However, a quick search of eBay and other resale sites found dozens of used kits and components for sale. Repair parts were also available as we’ ll note at the end of the article.

We’ ll go through the article as I originally wrote back in 1979 as a Technical Bulletin for members of the Massachusetts Better Home Heat Council during the‘ Retrofit Program’ and then at

Figure 1

the end we’ ll review the suggestions for replacements for discontinued components. I’ m not recommending going back to these kits, just offering my help to those who have or never stopped. It’ s also my opinion that any testing of combustion is better than no testing at all and that’ s the truth, a fact!

This material was originally published in 1979, as previously noted, and again in Fueloil & Oil Heat, September 1991 and also published as excerpts in our texts,‘ COMBUSTION & Oil Burning Equipment’ in 1995 and‘ Advanced Residential Oilburners in 2007 and several times here in Fuel Oil News.

The ability for some to diagnose and repair oilburners seems sometimes out of control. Regrettably, as these problems have increased, we have not used all of the tools available to us. It is almost impossible today to properly service‘ state of the art’ burners by the‘ let’ s eyeball it’ method. Also, due to the use of heavier concentrations of biofuels the ability to use the cad-cell and primary control is also going away due to the darker characteristics of bio-based flames.

Annoying and costly repeat calls have increased while no one seems to know why. Or do we? Some companies seem to have fewer problems than others. Why?

We hope to answer some of these questions here or at least get you to look over how and why you do it‘ your way.’ Since about 1911 the oilburner service industry has had testing equipment available to us to analyze burner performance. The smoke tester was introduced in 1948.

In the 1970’ s and 1980’ s the combustion test kit was used primarily to test‘ steady-state efficiency’ and lost most of its credibility as a true service tool. It is as essential as our flashlight for good burner service.

Since many of us may not have used the kit as often as others or abandoned it for electronic types, we will concentrate on reviewing the basics of instrument use and instrument quality.

The purpose of this document is, therefore, to eliminate as many discrepancies as possible which come about due to improper care and maintenance of the instruments used in the field. Many servicemen still do not understand the importance and meaning of steady-state test conditions. For their benefit we will re-define the term and discuss the proper use and checkout procedures for these tools.

Steady-state; a condition that exists when the burner has fired long enough to have reached unchanging temperatures. Steadystate is most easily confirmed by the temperature of the flue gas. Steady-state conditions have been reached when there has been no change in temperature for two minutes.

Preparing the unit for testing; it is advised that two holes be made in the stack to speed up testing which is especially important with today’ s smaller more efficient units. Location of these holes is very important. It was previously recommended that they should both be located one to two smoke pipe diameters from the breech, excluding all elbows, but always between the breech and draft regulator. Today, most Figure 2 OEMs recommend at the breech.

By inserting the stack thermometer, Figure 2, in one-hole, steady state conditions will be proved as soon as possible and leave the other hole for other tests. Another test hole must be located, preferably within 12 inches, over the fire or in the door closest to fire for overfire draft readings, Figure 3.

Figure 3

INSTRUMENTS

Before performing any tests, the instruments must be checked to ensure good test readings:

Check the dry-type draft gauge, Figure 4, check to be sure the gauge operates smoothly.

Figure 4

www. fueloilnews. com | FUEL OIL NEWS | FEBRUARY 2026 19