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Efficiency Testing

Efficiency Testing

Efficiency of an appliance is the difference between the possible heat outputs produced compared to the actual amount of heat obtained from the appliance. For example: a 60,000 BTU input furnace with an output of 48,780 would have an operating efficiency of 81.3%. Another 60,000 BTU input furnace could have an output of 44,000 BTU resulting in an efficiency of just 73%.

The objective of efficiency testing is to obtain as high an efficiency rating as possible, taking into account all factors of operating, cost, equipment life, and most important the end result: "comfort" in the conditioned space. In order to achieve this we must make certain that proper airflow over the furnace heat exchanger is correct, while at the same time ensuring that the flue product temperature is within the manufacturer's specifications. Too low a temperature may cause condensation (water vapour) to damage the appliance and flue. On the other hand, if too high a temperature is present in the flue, damage of the heat exchanger may occur as well as increasing the operating cost.

Efficiency testing is broken down into three components:

  • Overall combustion performance.

  • Burner performance.

  • Heat exchanger condition and operation.

The procedure for performing efficiency testing and adjustment of an appliance is done as follows:

  • Ensure that the appliance is operating within the correct fuel pressure as specified by the manufacturer.

  • The actual input is determined and recorded.

  • Temperature rise is taken, recorded and blower adjusted, if necessary.

  • Control settings recorded and adjustments made if necessary.

  • Flue temperature taken and recorded.

  • Draft readings taken before, during and after the appliance cycle and recorded.

  • On some units an over fire draft or neutral pressure point is tested for its exact position, adjusted if necessary and information recorded.

  • Combustion efficiency-proper flame pattern and appearance are observed and adjusted as necessary.

    Sampling of the flue gas with a special detection device (manufactured by Bacharach) will provide us with carbon dioxide (CO2) %, carbon monoxide (CO) %, Oxygen (O2) % and soot spot (oil furnaces only) which are all again recorded.

The final appliance efficiency can then be determined once all the tests have been performed.

Efficiency and combustion testing should be performed at least every five years on standard and mid-efficiency appliances, every other year for high efficiency appliances and every year for oil fired appliances (due to the higher cost of fuel and greater potential to slip out of balance).

During the past year Custom Vac has performed more efficiency and combustion tests than in the past 10 years combined. The results indicated that some high efficiency furnaces had dropped to the 88-90% range and once cleaned, adjusted, modified, etc. we raised them back to 98-99% combustion efficiency. A few had very high levels of carbon monoxide (CO) gas, a deadly combustion product to have present.

So, if you are concerned about the condition of your appliance or ever wondered what the real efficiency is, contact Custom Vac by phone or by e-mail. If you require additional information visit the Bacharach site. For your convenience we have provided you with a link below.

Custom Vac - Heating - Cooling - Air Quality Control - Duct Cleaning - Systems Analysis,  Winnipeg, Manitoba. Since 1970.Bacharach Inc.   Bacharach Inc.
Honeywell   Honeywell


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1567 Logan Avenue
Winnipeg, Manitoba
R3E 1S5
T. 204-775-7744
T. 204-772-5799
F. 204-774-8557


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