Oil Boiler Efficiency and output

Bombesly · 17-02-2014 1:50pm #1

Hi,

I've download various forms from the seai website hoping that I'll make some savings by being energy efficient around the house. So far so good, from an electrical point of view I've put in place various (way of doin thing) and it works however when it comes to oil and boiler I'm a bit lost

I've looked around and found the HARP database on the seai website. I looked into the boiler and found the right info to key it in : http://www.seai.ie/Your_Building/BER/BER_Assessors/Technical/Harp_Database/Gas_LPG_and_Oil_Boilers/Details/?ID=2337

I hope that link work. I've got the 70 one so with an estimated output of 20.52 KW. Now my question is can I find out how many KWh I spend per L of oil with an efficiency rating of 82%?

How is an effieciency estimated based on? Heat loss due to tranfert of water trough pipes etc I assume and then what else?

Many thanks in advance for your help

agusta · 17-02-2014 9:44pm

Wearb · 17-02-2014 10:08pm

You will come across two types of efficiency. One is the boiler efficiency and that is the amount output that you can get from your boiler when running at its designed capacity, minus losses through the flue and boiler casing. e.g. (and without getting too pedantic about it) if you put in fuel with a capacity to provide 10kw and your boiler provides 9kw from that 10 then your boiler is said to be operating at 90% efficiency. A lot of modern boilers operate at 100% and over. This happens because the latent heat contained in the water vapour is also turned into usable heat.

The second efficiency that you will come across is the seasonal efficiency. This takes into account that your boiler will not always run at design load, as zone valves close and outside temperatures rises.

shane0007 · 17-02-2014 10:26pm

You have many considerations when evaluating boiler efficiency.
The main ones are combustion efficiency & boiler seasonal efficiency.
So your Firebird 70-90 will be factory set to 80,000 Btu which is approx 23.4kw. For every litre of kerosene, you obtain approx 9.8kwh of energy.
Combustion efficiency calculates depending on the fuel you are burning, the calorific value going in & the energy obtained in the combustion chamber, so if you are inputting 9.8kw per hour, your particular boiler should achieve a gross efficiency of circa 84%, which will give you a combustion output of 8.2kwh per litre.
Your Sedbuk or Harp seasonal efficiency is based on the kwh output of,the boiler measured at the flow pipe from the boiler, so it is interested in the overall efficiency of the boiler taking into account losses within the boiler metal components, losses to surrounding atmosphere, boiler insulation losses, etc.
So your boiler with efficiency of 85.5% will achieve an actual output of 7.01kwh per litre of fuel inputted.
After that, you must contend with your system losses.

A high efficiency boiler will recover the losses to atmosphere through the flue by means of a secondary heat exchanger, therefore a combustion efficiency net of circa 99% can be achieved with Sedbuk/Harp achieving 95-97% for the Vortex, so you can see the considerable savings that can be achieved by upgrading the boiler.

shane0007 · 17-02-2014 10:28pm

Wearb wrote: »

(and without getting too pedantic about it)

Sorry, Wearb, I was typing at the same time as you & I was getting pedantic about it!

Bombesly · 18-02-2014 10:48am

Thanks very much for the help guys, very appreciated that and sometime being pedantic just HEAT the spot

Oil Boiler Efficiency and output

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