Bacharach combustion analyzer

DaveGateway

How does a Bacharach combustion analyzer calculate efficiency?

What is the criteria?

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Ken D.

Bacharach

They use measured quantities of carbon dioxide, oxygen, excess air( atmospheric air) and temperatures such as flue gas and ambient(surrounding Air). Using mathamatical formulae they calculate combustion efficiencies based on levels of the different readings as percentages. The higher the CO2 readings the higher efficiencies. The higher the O2 the lower the efficiencies. The higher the stack (flue gas) temperature, the lower the eff. The higher the stack temp. means that extra heat is going up the chimney rather than heating the house, thus higher stack temperature and lower eff. CO2 and O2 run opposite to each other under normal circumstances. That is the higher the CO2 the lower the O2. They can in certain undesirable circumstances run the same (high O2 and high CO2), but this is an abnormal and dangerous situation. Normally, the high CO2 means more complete combustion as the low O2 means most of the oxygen was used up in the combustion process. Higher O2 and low CO2 means that the oxygen was not used in combustion and is simply going up the chimney taking heat with it ( higher stack temp). The levels of CO2 and O2 also are connected to how clean the fire burns. Excess air is the amount of air added to the combustion over what is actually needed to attain clean combustion. Any air or parts thereof not used in combustion go up the chimney, taking heat with it, thus higher stack temp. Ideally, you want low O2, High CO2 and low stack temp., although another problem is higher amounts of Carbon Monoxide at higher CO2 levels. That is why combustion testing is so important. These calculations are already done for you in the form of the slide chart that comes with the older style bottle CO2 and O2 tester or the newer electronic testers calculate it automatically in the form of a printed or continuous readout. The actual formulae can be obtained by contacting Bacharach or the furnace or boiler manufacturer. Hope this helps.

Fred Harwood

Analyser

The kit contains several pieces of equipment used, in essence (after cleaning and sealing the boiler against air infiltration), to measure the temperature and CO2 content of the flue gas at the boiler breech. A slide rule in the kit gives the combustion efficiency and stack loss for various CO2 amounts and net stack temperatures. You just measure, then look up the results on the slide rule. For example, #2 heating oil, 12% CO2, and a net stack temp of 400F gives 83.75% efficiency, about the most you can get without condensing the water in the flue gas and recovering the heat. A special boiler would be needed for that.

Kevin_21

bacharach

First you have to buy one
Over here on the west coast of canada. And trying to find a distributor, called bacharach canada they gave me four numbers not one has got back to me its been two weeks now. anyone have any ideas.
Tks. Kevin

Rudy

Give me a call

Hi Kevin, I deal mostly with Bacharach US but I can help you out, give me a call or email me and I'll find a distributer.
740-594-0033
rudy@eurekanet.com

Rudy

SSE Calculations

Hi John, my (limited) understanding is that all analyzer manufacturers use the "Seigert equation" with some minor changes to reflect btu content in fuels, etc.

I don't quite understand why but apparently the specific equations used by the different manufacturers are propriatary.

jbplumber

Goodman

I asked Goodman Manf. that very question and have yet to get the answer. "If I drill a hole in the exhast vent on a 90+ furnace and install my Bacharach.60 analyzer probe what should it read"? on a 80 + ? does any one out there know. On the new furnaces of today about all one can do is adjust gas pressure.I understand that Bacharach offers guidance in the user manual but thats not my question. J.Lockard

Rudy

Test results

Jim, almost all atmospheric and 80+ equipment should read a 6% to 9% O2 and certainly less than 100ppm CO air free.

Most 90% equipment will run in the same range.

If you need some help getting the specific info from Goodman (or whatever manufacturer), get in touch with me and I'd be happy to talk with them.

One important thing to keep in mind (particularly if you are installing/servicing the same equipment most of the time) is to watch for readings that are not what you have seen on other installations - it may be indicative of a problem.

Rudy

Test results

Jim, almost all atmospheric and 80+ equipment should read a 6% to 9% O2 and certainly less than 100ppm CO air free.

Most 90% equipment will run in the same range.

If you need some help getting the specific info from Goodman (or whatever manufacturer), get in touch with me and I'd be happy to talk with them.

One important thing to keep in mind (particularly if you are installing/servicing the same equipment most of the time) is to watch for readings that are not what you have seen on other installations - it may be indicative of a problem.

jbplumber

Thanks

Rudy. J.Lockard

DaveGateway

Thank you.



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Unknown

Jim this is one of the things

we cover in our class on "Testing Design Gas Equipment". I try as best I can to discuss the readings obtainable with 80+ and 90+ equipment and also various high end equipment.

Manufacturers are getting better at getting this information out. I would guess in the future it will be included in service manuals. I have been trying to get this done now for many years.

The figures that Rudy gave are definitely in the ballpark. There are cases on some equipment due to burner design that readings may vary somewhat. I can tell you this testing high end equipment can solve some of those nuisance problems that no one can figure out why it keeps shutting down. Many times it is the need to fine tune the equipment.

Jim Davis_3

Combustion Efficiency Calculations

John is this a trick question? As taught in class and based on 27 years of using combustion analyzers, 90% of all combustion efficiency calculations programmed into combustion analyzers are either mechanically unsafe or mechanical impossibilities. The remaining 10% are in error approximately 15-20%.. This information has never been proven otherwise. The efficiencies we try to attain on all equipment should be their maximum mechanical and safety efficiency, and this cannot be calculated by any analyzer on the market today. However it is true evaluation of the accurate data that analyzers can collect.

Boiler Guy

Kevin

You might want to re-evaluate Bacharach in Canada! Ridiculous turnaround time for recalibration. We've converted to Testo and loving them. JMHO