A combustion analyzer turns a furnace or boiler's exhaust into numbers you can compare from one visit to the next. NAVAC has introduced the NMA1, and the ACHR News item on the NAVAC NMA1 combustion analyzer says the new instrument "combines combustion testing, pressure measurement, data storage, and wireless connectivity in one handheld instrument." For a homeowner, the useful question is not what the tool can do. It is what the readings should mean to you, and whether you will still have them after the tech packs up.
What the Analyzer Measures
Most combustion analyzers report flue gas oxygen, carbon monoxide in the flue, and flue gas temperature. Many also report a draft or pressure value and calculate an efficiency estimate from those inputs. Each number answers a different question. Oxygen and carbon monoxide describe how completely the fuel is burning. Flue temperature tells you how much heat is leaving up the vent instead of staying in the house. Draft or pressure shows whether the exhaust is moving the way the appliance was designed to move it.
None of these numbers means much alone. A single flue reading on a cold afternoon is a snapshot. Two readings taken under the same conditions, a year apart, show a trend. That is the reason the record matters more than the instrument.
What to Ask the Tech For
Before the tech starts, ask for the full printout or saved file, not just a verbal summary. A usable record includes the date, the appliance make and model as printed on the nameplate, the readings taken before any adjustment, the readings taken after, and the location where each sample was drawn. If the readings are taken at more than one point, such as at the flue and in the room, label each one.
Ask when the analyzer was last calibrated and what the manufacturer's maintenance schedule calls for. The answer belongs on the paper, not in your memory. If the instrument stores data, ask whether the stored readings can be exported to you as a copy. The summary lists data storage and wireless connectivity, so the capability is there. Whether you get the file is a question you have to ask.
Keep Your Side of the Record
Build a simple folder, paper or digital, with four items. First, the nameplate model and serial number, photographed on the day the appliance is in good order. Second, the filter size and the date it was last changed. Third, every combustion printout. Fourth, a dated note for any service that changed the burner, the gas valve setting, or the venting. When the next tech asks what changed, you will have an answer that does not depend on who remembers what.
A multimeter is a fair tool for checking the low-voltage control side. At the thermostat and the control board, a 24-volt control circuit should read close to 24 volts AC when the system is powered and no call is active or when the call is applied, depending on the wiring. Note the reading and the condition under which you took it. Do not adjust burners, gas valves, or combustion settings yourself. Those adjustments belong to a licensed technician with the analyzer in hand.
Safety Limits of the Homeowner's Role
Carbon monoxide is the reason combustion testing exists, and it is also the reason you should keep a working CO alarm near sleeping areas and on each level of the home, installed and tested as the manufacturer directs. If an alarm sounds, or if a reading comes back high, leave the area and call your gas utility or a licensed technician under your local rules. Do not try to diagnose the appliance while the alarm is active. This article is service information, not a substitute for emergency guidance.
Reading the Trend
Once you have two or three records, compare them without rushing to a verdict. Look for drift in oxygen or flue temperature, a change in draft after a filter swap or a cleaning, or a difference between visits that the tech explains with a specific cause. A change is a question to ask, not a finding. Bring the folder to the next service call, hand the tech your last printout, and ask what has moved and why.
The point of a combustion analyzer is not to make the homeowner an instrument technician. It is to make the service history readable. A handheld instrument with stored data and wireless capability can produce a record that outlasts any single visit. Make sure that record ends up on your side of the wall.