Anybody replaced a Cat G boiler recently?

[gmartine]

I was paying particular attention to a British Gas radio ad the other day where certain efficiency and cost saving claims where being made. Oh and there it is, a disclaimer at the end of the ad said in rapid fashion that the savings claimed were based on a Band G boiler or less than 70% efficiency. Which got me thinking when I last changed out a boiler that still had a pilot light, beginning of the year I think so not many.

Category G Boilers Rating List

Full listing of all G rated boilers that can qualify for the boiler scrappage scheme from the UK government.

www.electricityprices.org.uk

 

[Last Plumber]

I haven't taken one out in years in domestic premises. I just picked one of my favourites and checked, Glow Worm Hideaway, 71.7% SEDBUK.
Vaillant ecotec 618 = 89% ish so around 17% better?

What were the amazing feats being offered in the way of energy saving? How much COULD YOU save in a year?
How quickly could you save the outlay back? Where they giving you anything as a trade in?

 

[Chuck]

If you have time on your hands refer, refer the advert to the Advertising Standards Authority. Their rules are complicated but I'm fairly sure you can't advertise a saving that virtually nobody will achieve and use a small-print disclaimer as cover.

 

[gmartine]

What were the amazing feats being offered in the way of energy saving? How much COULD YOU save in a year?
How quickly could you save the outlay back? Where they giving you anything as a trade in?

Don't recall hearing anything about a trade in, just a blurt about changing to a newer boiler. They were claiming something like £800 odd a year in savings by converting from a band G boiler so your annual gas bill would obviously have to be in the region of £4k.

 

[Last Plumber]

If a typical household uses what the government figures say they do (they seem about right to me for an average), you could only save a couple of hundred quid a year from band G to A.
I know they can't lie in these ads but they can use excitingly enticing figures.

I also think most of these boilers have gone now. The reality in my part of the world is replacing modern boilers with modern boilers and there is little in the way of saving as you know.

 

[gmartine]

Well that was the point of the post, not to contest the stated numbers but their terms of reference which would as you confirmed be under rarefied conditions.

 

[SimonG]

I get it all the time on the oil boilers. Theres still a lot of worcester heatslaves standard efficiency combis kicking about. I go to service them and customers are like I can save 500 a year on oil if I get a new boiler. They've spoken to companies on the phone offering massive fuel savings if they swap to a new combi.

Absolute ballcocks.

 

[John.g]

What kind of flue gas temperatures are you seeing after servicing HE oil boilers?, my 17 year old SE Firebird with a Riello G5x burner has a flue gas temperature of ~ 235C, I would be happy to see around 80C with a brand new HE boiler with savings of ~ 7%. I think these boiler manufacturers add on the full potential condensing benefits of around 7% for oil and 11% for gas.

Are the flue gas analysis efficiencies presented on SE boilers based on the HHV of the fuel and based on the LHV for HE boilers and if so, I wonder why.

 

[SimonG]

What kind of flue gas temperatures are you seeing after servicing HE oil boilers?, my 17 year old SE Firebird with a Riello G5x burner has a flue gas temperature of ~ 235C, I would be happy to see around 80C with a brand new HE boiler with savings of ~ 7%. I think these boiler manufacturers add on the full potential condensing benefits of around 7% for oil and 11% for gas.

Are the flue gas analysis efficiencies presented on SE boilers based on the HHV of the fuel and based on the LHV for HE boilers and if so, I wonder why.

Anywhere from 55 to 85 degrees depending on the manufacturer.

Compared to 180 upto 350 but the 350 was a very old boiler, now gone the journey. Had to add a radiator in the utility because the customer couldn't understand why the room was cold with the new boiler in.

 

[John.g]

We used to use 4.5% efficiency gain/loss per 100C flue gas temperature on the large industrial boilers.
My boiler at 235C with 25C air intake temp would equate to ~ 84/85% efficiency.
The 72% boiler above must be running with a flue temp of somewhere around 500C?.

 

[gmartine]

Had to add a radiator in the utility because the customer couldn't understand why the room was cold with the new boiler in.

Ha, yes funny that. As with gas the rating of any older boiler never did take "waste" heat into account but maybe they should've tried by including the boiler itself as an emitter.