Boiler Input-Output Efficiency Calculations

[Damon Apple]

Hi guys,

I am choosing to install in my project homework a worcestor-bosch 15i System boiler and i need to work out the
Input, Output and efficiency workings out on all settings.

I am totally stuck even after worcestor technical team sent me the installation data brochure but i just cant work it out.

This is what I am doing Max Rated Output=15kw
Max Rated Input=15.4kw

So i assumed output divided by input x 100 = 97.4% Gross efficiency and if i divide this by 1.11 i get the Net efficiency of 87.75%.

Now heres the problem worcestor bosch claim this has an efficiency of 90.1%

What am i doing wrong?

Link attached for the installation brochure instructions table etc...

http://www.worcester-bosch.co.uk/ca...r-i-system--manufactured--aug-09---jan-11.pdf

Any help very much appreciated :mad2:

 

[doitmyself]

This is what I am doing Max Rated Output=15kw
Max Rated Input=15.4kw

So i assumed output divided by input x 100 = 97.4% Gross efficiency and if i divide this by 1.11 i get the Net efficiency of 87.75%.

Now heres the problem worcestor bosch claim this has an efficiency of 90.1%

What am i doing wrong?

Nothing!

The efficiency figure in the manual is the "SAP2005 Seasonal Efficiency", which is calculated by a fairly complicated formula designed to simulate the usage of the boiler over a year. This has now been replaced by the "SAP2009 Annual Efficiency" which, for the 15i is 88.8%. You can read about this at http://www.sedbuk.com

 

[doitmyself]

<br>
This is what I am doing Max Rated Output=15kw<br>
Max Rated Input=15.4kw<br>
<br>
So i assumed output divided by input x 100 = 97.4% Gross efficiency and if i divide this by 1.11 i get the Net efficiency of 87.75%.<br>
<br>
Now heres the problem worcestor bosch claim this has an efficiency of 90.1%<br>
<br>
What am i doing wrong?

Nothing!

The efficiency figure in the manual is the "SAP2005 Seasonal Efficiency", which is calculated by a fairly complicated formula designed to simulate the usage of the boiler over a year. This has now been replaced by the "SAP2009 Annual Efficiency" which, for the 15i is 88.8%. You can read about this at Sedbuk

 

[Damon Apple]

Thankyou for your assistance