So generally the efficiency stated on the rating plate of the boiler will always be lower than the measured efficiency of combustion. Net Combustion Efficiency v Gross Combustion efficiency Net combustion efficiency calculations assume that the energy contained in the water vapour which is formed as a product of combustion is recovered and is not exhausted from the flue or stack.

Read More• Net rating MBH = Net AHRI rating MBH = Net IBR rating MBH: Same for these three; they all share the exact definition. It's obtained by multiplying the gross output by 0.85. This equation assumes that 15 percent of a boiler's gross output is lost through the piping before reaching the heat emitters.

Read MoreBoiler Efficiency and Combustion. A broad overview of the combustion process, including burner types and controls, and heat output and losses. This Module is intended to give a very broad overview of the combustion process, which is an essential component of overall boiler efficiency. Readers requiring a more in-depth knowledge are directed

Read MoreOlder boilers give input figures as gross, but don't necessarily tell you. Newer boilers give input figures as net, but don't necessarily tell you. If you divide output by input and get a daft efficiency number of more than , you know you've been given the net figure.

Read More1/11/2020 · Since it's difficult to remember all the details of central heating problems and gas boiler problems we deal with, we decided to keep this log of some of the problems and how we've attempted to sort them out. Putting this information online allows other people to look for clues and ideas. Too often gas service engineers and central heating

Read MoreThis value may be expressed in two ways 'Gross' or 'Net' calorific value. Gross calorific value This is the theoretical total of the energy in the fuel. However, all common fuels contain hydrogen, which burns with oxygen to form water, which passes up the stack as

Read MoreOF BOILERS Bureau of Energy Efficiency 1 1.1 Introduction Performance of the boiler, like efficiency and evaporation ratio reduces with time, due to poor combustion, heat transfer fouling and poor operation and maintenance. Deterioration of fuel quality and water

Read More16/8/2017 · The input is also used to determine the efficiency of the boiler for example; a boiler with an input of 150,000 Btu/hr and a gross output of 135,000 would have an estimated combustion efficiency of 135,000÷150,000= .90×100=90% eff. Next we have the boiler output, which can be listed in several ways. Which one to use is really dependant on the

Read MoreSo generally the efficiency stated on the rating plate of the boiler will always be lower than the measured efficiency of combustion. Net Combustion Efficiency v Gross Combustion efficiency Net combustion efficiency calculations assume that the energy contained in the water vapour which is formed as a product of combustion is recovered and is not exhausted from the flue or stack.

Read MoreGCV= Gross calorific value of the fuel. Indirect Efficiency The indirect efficiency of a boiler is calculated by finding out the individual losses taking place in a boiler and then subtracting the sum from . This method involves finding out the magnitudes of all the

Read MoreTypically the difference between the value of net combustion efficiency and the value of gross combustion efficiency for a natural gas fuelled boiler is around 8% with the net value being higher than the gross value. Most boiler manufacturers now quote their boiler efficiencies based on the net combustion efficiency.

Read More1/11/2020 · Logically, boiler manufacturers should use gross figures. They tell us exactly how much of the input energy is useful to us and how much is lost. Unfortunately this would make the boilers now look less efficient, so the manufacturers still use net figures.

Read More15/12/2010 · Net Efficiency: What's it net of and how is it calculated? Gross Efficiency: What is is measuring? Obviously efficiency of the boiler but what does that mean? CO2 - If the customer's lost their manual what's a good figure to aim for? O2 - Between 5.5% and 6.0%

Read MoreBoiler Efficiency Gross and Net Efficiency. Efficiency, in heating appliances, is not about how quickly your boiler heats up your home. It's a measure of how much of the energy you've paid for is used to make your home warmer and how much is lost through the

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