Are SEDBUK ratings meaningful?

[JonCa]

I am interested to find out more about how the SEDBUK rating is achieved/awarded.

Things like :
1/. How long is the test period and what does it involve:
I gather the 46kw Vaillant Ecotec + HE boiler always has a full burn for the first hour of firing, so how does it achieve a 90.5% efficiency and an A rating when its installation will normally not need a full burn for such a long period. Surely efficiency is about more than its ability to extract heat, does it include things like modulating down for best use of resource

2/. Boiler controls used for test:
It seems that using boiler manufacturers own brand controllers can significantly affect the efficiency of a boiler,
how can I find out which controller a boiler was tested with enabling my ability to be able to install the most efficient solution. Shouldn't that be part of the published results?

 

[ianmcd]

SEDBUK ratings are no longer relevant as I have just found out , I beleive that the ABC etc have been replaced for the new green deal wont argue with anyone if they say different as have not been told officially , but as for the older rating they take an appliance and run it for 70 Hours at maximum rate and that is how it gets its SEDBUK rating nothing to do with external controls and I dont know of any boiler that will run flat out for 70 Hours continuously but that is how it is calculated

 

[Dan Robinson]

It always was a load of boolax

 

[gas112]

91 percent is under optimum conditions in a science lab in the real world installed on existing systems after the first 20 mins prob down to around 82%.
Seebunk rating have been out for quite a while now and its efficiency wrote on boiler has to be above a certain figure think its 89% ish

 

[Biggles..]

Interesting as 91% shouldn't make it band A

98.4%eff @ 100% load
109% eff @ 30% load!

 

[bolshy]

All boilers installed have to be of a minimum efficiency equivalent to SEDBUK 2005/2009, 90% or 88% respectively, to comply with building regs.

So they replaced the SEDBUK ratings with efficiency figures, but the boiler still has to meet the required efficiency figure relating to the old SEDBUK band A.

They are obviously completely mad......

 

[ianmcd]

All boilers installed have to be of a minimum efficiency equivalent to SEDBUK 2005/2009, 90% or 88% respectively, to comply with building regs.

So they replaced the SEDBUK ratings with efficiency figures, but the boiler still has to meet the required efficiency figure relating to the old SEDBUK band A.

They are obviously completely mad......

really not sure what the new readings are Bolshy but 91.9% rings a bell not sure if this is for the green deal that is coming out or what but have been told that the old SEDBUK ratings are now obsolete not my game so wont argue with anyone that says different

 

[bolshy]

No, I can't get my head around it either. SEDBUK ratings are obselete, but they're using the same research from SAP 2005 and 2009, which formed the basis for the SEDBUK letter bandings to give us the new efficiency percentages. AFAIK.
Which begs the question, why bother?
Does anyone really give a flying fook whether it's SEDBUK band A, or SAP 2009 and 92% efficient?

 

[ALEC1]

especially when everyone knows that the cooler you run the boiler the more efficient it will be..

 

[JonCa]

Well, seems I touched a point of sensitivity here Thanks all for you feedback.

So historically, results based upon extremely unrealistic test methodology, seemingly with a high probability of being unable to complete the full test duration.
Recent energy indicators based upon same historical data methodology.

Simplistically its energy outmax over energy in max over 70 hours, although must be a bit more than that as my antique cast iron non-modulated lump ought to perform fairly well on that sort of basis

For the sake of clarity the results may be presented in a variety of ways to enhance something, but what..?...?... oh yes .... probably enhances sales of boilers

All in all its a really un-useful measure, that no-one seems to complain about, wonder why?

Thanks again

 

[JonCa]

especially when everyone knows that the cooler you run the boiler the more efficient it will be..

So a boiler that a boiler that produces no heat (coolest) is really really efficient ???

Sorry couldn't resist.

 

[D_Hailsham]

they take an appliance and run it for 70 Hours at maximum rate

Where does that come from? I can't find it documented anywhere.

 

[ianmcd]

they take an appliance and run it for 70 Hours at maximum rate

Where does that come from? I can't find it documented anywhere.

Honestly mate that is how they rate them I used to work for a boiler manufacturer and that is where the SEDBUK rating came from, admittedly that was some 10years ago so really do not know how they do it now

 

[bolshy]

98.4%eff @ 100% load
109% eff @ 30% load!

As far as I know, nothing which burns gas alone can be more than 100% efficient. They use the calorific value of gas based on the heat produced by burning it only. The gross calorific value, or higher calorific value involves calculating the total heat released by burning the gas AND returning all combustion products (including the water vapour) to the same temperature as the gas before it was burned.
Therefore the figures are a load of carp anyway

 

[JonCa]

Sorry, long and heavy..
Found this, http://www.boilers.org.uk/pages/sap2009.htm which provides a very broad overview, i.e tells you about it but...no real detail.

For simple guidance it is sufficient to look at the SAP 2009 annual efficiency, which is an estimate of efficiency when installed under typical conditions in Britain, taking into account climate, housing conditions, occupancy patterns, and controls.

FULL BURN is mentioned as being a data source for calculations. but as with all things its gov't implemented based upon EU standards.

- http://tools.decc.gov.uk/en/content/cms/emissions/sap/sap.aspx Dept Energy & Climate Change (control everything dont they) short page about SAP, inc faq, points to BRE.
- http://www.bre.co.uk/sap2009/page.jsp?id=1642 BRE pages that according to DE&CC cover the 2009 consultation also offers SAP2009 download.
- SAP2009 points in section D3 to "Boiler Efficiency Directive" for test methodology. Directive from http://eur-lex.europa.eu/LexUriServ/site/en/consleg/1992/L/01992L0042-20050811-en.pdf This directive under article 5 specifies the useful efficiency requirements and places a requirement for a standard.
-I believe that EN 303-3 is that standard and an uncontrolled (presumably draft) copy of EN 303-3:1998 can be found here http://tinyurl.com/aymwsl9 Then like 99% of EN's its hard reading, but section 6.4 covers measuring "useful efficiencies" but I'm not seeing anything about significantly long test runs although this may be part of another measure or simply to do with manufacturers QA processes.
I pass